Publications by year
In Press
Khan S, Aragao L, Iriarte J (In Press). A UAV-Lidar System to Map Amazonian Rainforest and its Ancient Landscape Transformations. International Journal of Remote Sensing
Jones M, Aragão LEOC, Dittmar T, Rezende CE, Almeida MG, Johnson BT, Marques JSJ, Niggemann J, Rangel TP, Quine TA, et al (In Press). Environmental Controls on the Riverine Export of Dissolved Black Carbon.
Global Biogeochemical CyclesAbstract:
Environmental Controls on the Riverine Export of Dissolved Black Carbon
Each year, tropical rivers export a dissolved organic carbon (DOC) flux to the global oceans that is equivalent to ~4% of the global land sink for atmospheric CO¬2. Among the most refractory fractions of terrigenous DOC is dissolved black carbon (DBC), which constitutes ~10% of the total flux and derives from the charcoal and soot (aerosol) produced during biomass burning and fossil fuel combustion. Black carbon (BC) has disproportionate storage potential in oceanic pools and thus its export has implications for the fate and residence time of terrigenous organic carbon (OC). In contrast to bulk DOC, there is limited knowledge of the environmental factors that control riverine fluxes of DBC. We thus completed a comprehensive assessment of the factors controlling DBC export in tropical rivers with catchments distributed across environmental gradients of hydrology, topography, climate and soil properties. Generalised linear models explained 70% and 64% of the observed variance in DOC and DBC concentrations, respectively. DOC and DBC concentrations displayed coupled responses to the dominant factors controlling their riverine export (soil moisture; catchment slope, and; catchment stocks of OC or BC, respectively) but varied divergently across gradients of temperature and soil properties. DBC concentrations also varied strongly with aerosol BC deposition rate, indicating further potential for deviation of DBC fluxes from those of DOC due to secondary inputs of DBC from this unmatched source. Overall, this study identifies the specific drivers of BC dynamics in river catchments and fundamentally enhances our understanding of refractory DOC export to the global oceans.
Abstract.
2021
de Oliveira G, Brunsell NA, Chen JM, Shimabukuro YE, Mataveli GAV, dos Santos CAC, Stark SC, de Lima A, Aragao LEOC (2021). Legacy Effects Following Fire on Surface Energy, Water and Carbon Fluxes in Mature Amazonian Forests.
Journal of Geophysical Research: Biogeosciences,
126(5).
Abstract:
Legacy Effects Following Fire on Surface Energy, Water and Carbon Fluxes in Mature Amazonian Forests
The ongoing deforestation process in Amazonia has led to intensified forest fires in the region, particularly in Brazil, after more than a decade of effective forest conservation policy. This study aims to investigate the recovery of two mature sub-montane ombrophile Amazonian forests affected by fire in terms of energy, water and carbon fluxes utilizing remote sensing (MODIS) and climate reanalysis data (GLDAS). These two forest plots, mainly composed of Manilkara spp. (Maçaranduba), Protium spp. (Breu) (∼30 m), Bertholletia excelsa (Castanheira) and Dinizia excelsa Ducke (Angelim-Pedra) (∼50 m), occupy areas of 100.5 and 122.1 km2 and were subject to fire on the same day, on September 12, 2010. The fire significantly increased land surface temperature (0.8°C) and air temperature (1.2°C) in the forests over a 3 years interval. However, the forests showed an ability to recover their original states in terms of coupling between the carbon and water cycles comparing the 3-year periods before and after the fires. Results from a wavelet analysis showed an intensification in annual and seasonal fluctuations, and in some cases (e.g. daily net radiation and evapotrasnspiration) sub-annual fluctuation. We interpreted these changes to be consistent with overall intensification of the coupling of energy balance components and drivers imposed by climate and solar cycle seasonality, as well as faster time scale changes, consistent with a shift toward greater forest openness and consequent reduction in the interception of incoming solar radiation by the canopy.
Abstract.
2020
Vancutsem C, Achard F, Pekel J-F, Vieilledent G, Carboni S, Simonetti D, Gallego J, Aragao L, Nasi R (2020). Long-term (1990-2019) monitoring of tropical moist forests dynamics.
Sullivan MJP, Lewis SL, Affum-Baffoe K, Castilho C, Costa F, Sanchez AC, Ewango CEN, Hubau W, Marimon B, Monteagudo-Mendoza A, et al (2020). Long-term thermal sensitivity of Earth's tropical forests.
Science,
368(6493), 869-874.
Abstract:
Long-term thermal sensitivity of Earth's tropical forests.
The sensitivity of tropical forest carbon to climate is a key uncertainty in predicting global climate change. Although short-term drying and warming are known to affect forests, it is unknown if such effects translate into long-term responses. Here, we analyze 590 permanent plots measured across the tropics to derive the equilibrium climate controls on forest carbon. Maximum temperature is the most important predictor of aboveground biomass (-9.1 megagrams of carbon per hectare per degree Celsius), primarily by reducing woody productivity, and has a greater impact per °C in the hottest forests (>32.2°C). Our results nevertheless reveal greater thermal resilience than observations of short-term variation imply. To realize the long-term climate adaptation potential of tropical forests requires both protecting them and stabilizing Earth's climate.
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Author URL.
2019
Fonseca MG, Alves LM, Aguiar APD, Arai E, Anderson LO, Rosan TM, Shimabukuro YE, de Aragão LEOEC (2019). Effects of climate and land-use change scenarios on fire probability during the 21st century in the Brazilian Amazon.
Glob Chang Biol,
25(9), 2931-2946.
Abstract:
Effects of climate and land-use change scenarios on fire probability during the 21st century in the Brazilian Amazon.
The joint and relative effects of future land-use and climate change on fire occurrence in the Amazon, as well its seasonal variation, are still poorly understood, despite its recognized importance. Using the maximum entropy method (MaxEnt), we combined regional land-use projections and climatic data from the CMIP5 multimodel ensemble to investigate the monthly probability of fire occurrence in the mid (2041-2070) and late (2071-2100) 21st century in the Brazilian Amazon. We found striking spatial variation in the fire relative probability (FRP) change along the months, with October showing the highest overall change. Considering climate only, the area with FRP ≥ 0.3 (a threshold chosen based on the literature) in October increases 6.9% by 2071-2100 compared to the baseline period under the representative concentration pathway (RCP) 4.5 and 27.7% under the RCP 8.5. The best-case land-use scenario ("Sustainability") alone causes a 10.6% increase in the area with FRP ≥ 0.3, while the worse-case land-use scenario ("Fragmentation") causes a 73.2% increase. The optimistic climate-land-use projection (Sustainability and RCP 4.5) causes a 21.3% increase in the area with FRP ≥ 0.3 in October by 2071-2100 compared to the baseline period. In contrast, the most pessimistic climate-land-use projection (Fragmentation and RCP 8.5) causes a widespread increase in FRP (113.5% increase in the area with FRP ≥ 0.3), and prolongs the fire season, displacing its peak. Combining the Sustainability land-use and RCP 8.5 scenarios causes a 39.1% increase in the area with FRP ≥ 0.3. We conclude that avoiding the regress on land-use governance in the Brazilian Amazon (i.e. decrease in the extension and level of conservation of the protected areas, reduced environmental laws enforcement, extensive road paving, and increased deforestation) would substantially mitigate the effects of climate change on fire probability, even under the most pessimistic RCP 8.5 scenario.
Abstract.
Author URL.
de Oliveira G, Brunsell NA, Moraes EC, Shimabukuro YE, dos Santos TV, von Randow C, de Aguiar RG, Aragao LEOC (2019). Effects of land-cover changes on the partitioning of surface energy and water fluxes in Amazonia using high-resolution satellite imagery.
Ecohydrology,
12(6).
Abstract:
Effects of land-cover changes on the partitioning of surface energy and water fluxes in Amazonia using high-resolution satellite imagery
Spatial variability of surface energy and water fluxes at local scales is strongly controlled by soil and micrometeorological conditions. Thus, the accurate estimation of these fluxes from space at high spatial resolution has the potential to improve prediction of the impact of land-use changes on the local environment. In this study, Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) and Large-Scale Biosphere-Atmosphere Experiment in Amazonia (LBA) data were used to examine the partitioning of surface energy and water fluxes over different land-cover types in one wet year (2004) and one drought year (2005) in eastern Rondonia state, Brazil. The spatial variation of albedo, net radiation (Rn), soil (G) and sensible (H) heat fluxes, evapotranspiration (ET), and evaporative fraction (EF) were primarily related to the lower presence of forest (primary [PF] or secondary [SF]) in the western side of the Ji-Parana River in comparison with the eastern side, located within the Jaru Biological Reserve protected area. Water limitation in this part of Amazonia tends to affect anthropic (pasture [PA] and agriculture [AG]) ecosystems more than the natural land covers (PF and SF). We found statistically significant differences on the surface fluxes prior to and ~1 year after the deforestation. Rn over forested areas is ~10% greater in comparison with PA and AG. Deforestation and consequent transition to PA or AG increased the total energy (~200–400%) used to heat the soil subsurface and raise air temperatures. These differences in energy partitioning contributed to approximately three times higher ET over forested areas in comparison with nonforested areas. The conversion of PF to AG is likely to have a higher impact in the local climate in this part of Amazonia when compared with the change to PA and SF, respectively. These results illustrate the importance of conserving secondary forest areas in Amazonia.
Abstract.
Gouveia NA, Gherardi DFM, Wagner FH, Paes ET, Coles VJ, Aragão LEOC (2019). The Salinity Structure of the Amazon River Plume Drives Spatiotemporal Variation of Oceanic Primary Productivity.
Journal of Geophysical Research: Biogeosciences,
124(1), 147-165.
Abstract:
The Salinity Structure of the Amazon River Plume Drives Spatiotemporal Variation of Oceanic Primary Productivity
The Amazon river is a major source of terrestrially derived organic carbon to the tropical Atlantic Ocean. Field, satellite and a vertically generalized production model data were used to estimate empirical surface salinity and fit an inverse logit function to investigate the limiting effect of salinity on the productivity in the Amazon river plume. Satellite data included Moderate Resolution Imaging Spectroradiometer, Soil Moisture and Ocean Salinity, and Aquarius missions. Previous empirical surface salinity models have relied on a very narrow range of salinity values and satellite data to estimate the spatial extent of the river plume. The empirical surface salinity model presented here extended the range of salinity values and captures all the main surface mesoscale features, particularly those related to the main path of the low-salinity water. We also show that it is possible to gain new insights on the spatiotemporal variability of the Amazon river plume by improving the empirical surface salinity and expanding its sampling period with the aid of remote sensing data. The variability of primary productivity is dominated by the subannual (6 month) and annual (12 month) frequency bands. Low-salinity river water influences surface primary productivity continuously during the year through mechanisms associated with the western tropical Atlantic circulation and vertical mixing.
Abstract.
2018
Aragão LEOC, Anderson LO, Fonseca MG, Rosan TM, Vedovato LB, Wagner FH, Silva CVJ, Silva Junior CHL, Arai E, Aguiar AP, et al (2018). 21st Century drought-related fires counteract the decline of Amazon deforestation carbon emissions.
Nat Commun,
9(1).
Abstract:
21st Century drought-related fires counteract the decline of Amazon deforestation carbon emissions.
Tropical carbon emissions are largely derived from direct forest clearing processes. Yet, emissions from drought-induced forest fires are, usually, not included in national-level carbon emission inventories. Here we examine Brazilian Amazon drought impacts on fire incidence and associated forest fire carbon emissions over the period 2003-2015. We show that despite a 76% decline in deforestation rates over the past 13 years, fire incidence increased by 36% during the 2015 drought compared to the preceding 12 years. The 2015 drought had the largest ever ratio of active fire counts to deforestation, with active fires occurring over an area of 799,293 km2. Gross emissions from forest fires (989 ± 504 Tg CO2 year-1) alone are more than half as great as those from old-growth forest deforestation during drought years. We conclude that carbon emission inventories intended for accounting and developing policies need to take account of substantial forest fire emissions not associated to the deforestation process.
Abstract.
Author URL.
Martini DZ, Aragão LEOECD, Sanches IDA, Galdos MV, da Silva CRU, Dalla-Nora EL (2018). Land availability for sugarcane derived jet-biofuels in São Paulo—Brazil.
Land Use Policy,
70, 256-262.
Abstract:
Land availability for sugarcane derived jet-biofuels in São Paulo—Brazil
The aviation industry is committed to reducing its environmental impact and has established ambitious goals to decrease CO2 emissions by 50% by to 2050. The replacement of fossil fuels by jet-biofuels is one of the main strategies to attain the emission targets. Therefore, the aim of this study was to provide a detailed survey on land availability for sugarcane production, one of the most promising feedstock options for jet-biofuels, in the Brazilian state of São Paulo, where the technological resources are concentrated. This analysis was carried out by integrating georeferenced information on land use, protected areas, soil fertility, terrain slope and climatic conditions into a conditional decision support procedure, based on Boolean inference techniques. Our results showed that 3,501,590 ha would be potentially available for sugarcane expansion in the year 2013. Almost 80% of the mapped lands have high economic potential once they are located in a distance lower than or equal to 25 km from the processing units. If properly included in the productive sector, the available lands could increase sugarcane production by 73% in relation to current levels. That could lead to a growth of 147% (20.6 billion liters) in the ethanol production compared to the production obtained in 2015. Nevertheless, long-term policies, logistic improvements and environmental standard definitions on jet-biofuels still remain as major challenges to boost feedstock production, as well as, to implement financial and regulatory measures necessary to promote jet-biofuels production and use.
Abstract.
Kalamandeen M, Gloor E, Mitchard E, Quincey D, Ziv G, Spracklen D, Spracklen B, Adami M, Aragaõ LEOC, Galbraith D, et al (2018). Pervasive Rise of Small-scale Deforestation in Amazonia.
Scientific Reports,
8(1).
Abstract:
Pervasive Rise of Small-scale Deforestation in Amazonia
Understanding forest loss patterns in Amazonia, the Earth's largest rainforest region, is critical for effective forest conservation and management. Following the most detailed analysis to date, spanning the entire Amazon and extending over a 14-year period (2001-2014), we reveal significant shifts in deforestation dynamics of Amazonian forests. Firstly, hotspots of Amazonian forest loss are moving away from the southern Brazilian Amazon to Peru and Bolivia. Secondly, while the number of new large forest clearings (>50 ha) has declined significantly over time (46%), the number of new small clearings (
Abstract.
Iriarte J, De Souza J, Schaan D, Robinson M, Damasceno Barbosa A, Aragao L, Marimon BH, Marimon B, Brasil da Silva I, Khan S, et al (2018). Pre-Columbian earth-builders settled along the entire southern rim of the Amazon. Nature Communications
Berenguer E, Gardner TA, Ferreira J, Aragão LEOC, Mac Nally R, Thomson JR, Vieira ICG, Barlow J (2018). Seeing the woods through the saplings: Using wood density to assess the recovery of human-modified Amazonian forests.
Journal of Ecology,
106(6), 2190-2203.
Abstract:
Seeing the woods through the saplings: Using wood density to assess the recovery of human-modified Amazonian forests
Most of the world's remaining tropical forests have been affected by either selective logging, understorey fires, fragmentation or are regrowing in areas that were previously deforested. Despite the ubiquity of these human-modified forests, we have a limited knowledge of their potential to recover key traits linked to ecosystem processes and consequent services. Here we present data from 31,095 trees and saplings distributed across 121 plots of undisturbed and disturbed primary forests as well as secondary forests in the eastern Amazon. We examined the post-disturbance recovery trajectory of an important plant functional trait, wood density. We tested whether human-modified Amazonian forests are experiencing a rapid or a slow, or even impeded, recovery of this trait, which is associated with the provision of a fundamental ecosystem service—carbon storage. As expected, we found that the plot-level wood density of trees and saplings in disturbed primary and secondary forests was significantly lower than in undisturbed forests. However, there was no significant difference in the average wood density of saplings between disturbed primary and secondary forests, possibly indicating a process of secondarization. We also found evidence that the recovery of wood density in human-modified forests is being severely disrupted due to edge effects (in the case of disturbed primary forests) and high liana densities (in the case of both disturbed primary and secondary forests). Surprisingly, these two factors were more important predictors of wood density recovery than the time elapsed since the disturbance event. Synthesis. Plant communities in human-modified Amazonian forests appear to not be recovering a key functional property—wood density, which in turn may affect their ability to store carbon in the future. If the aim of conservation programs in tropical forests is to maintain existing rates of ecosystem functions, processes and services, then they must concentrate efforts on avoiding anthropogenic disturbance in areas of currently undisturbed forests. It is also vital to prevent further disturbance in human-modified forests to avoid disrupting even more their recovery.
Abstract.
Anderson LO, Ribeiro Neto G, Cunha AP, Fonseca MG, Mendes de Moura Y, Dalagnol R, Wagner FH, de Aragão LEOEC (2018). Vulnerability of Amazonian forests to repeated droughts.
Philos Trans R Soc Lond B Biol Sci,
373(1760).
Abstract:
Vulnerability of Amazonian forests to repeated droughts.
Extreme droughts have been recurrent in the Amazon over the past decades, causing socio-economic and environmental impacts. Here, we investigate the vulnerability of Amazonian forests, both undisturbed and human-modified, to repeated droughts. We defined vulnerability as a measure of (i) exposure, which is the degree to which these ecosystems were exposed to droughts, and (ii) its sensitivity, measured as the degree to which the drought has affected remote sensing-derived forest greenness. The exposure was calculated by assessing the meteorological drought, using the standardized precipitation index (SPI) and the maximum cumulative water deficit (MCWD), which is related to vegetation water stress, from 1981 to 2016. The sensitivity was assessed based on the enhanced vegetation index anomalies (AEVI), derived from the newly available Moderate Resolution Imaging Spectroradiometer (MODIS)/Multi-Angle Implementation of Atmospheric Correction algorithm (MAIAC) product, from 2003 to 2016, which is indicative of forest's photosynthetic capacity. We estimated that 46% of the Brazilian Amazon biome was under severe to extreme drought in 2015/2016 as measured by the SPI, compared with 16% and 8% for the 2009/2010 and 2004/2005 droughts, respectively. The most recent drought (2015/2016) affected the largest area since the drought of 1981. Droughts tend to increase the variance of the photosynthetic capacity of Amazonian forests as based on the minimum and maximum AEVI analysis. However, the area showing a reduction in photosynthetic capacity prevails in the signal, reaching more than 400 000 km2 of forests, four orders of magnitude larger than areas with AEVI enhancement. Moreover, the intensity of the negative AEVI steadily increased from 2005 to 2016. These results indicate that during the analysed period drought impacts were being exacerbated through time. Forests in the twenty-first century are becoming more vulnerable to droughts, with larger areas intensively and negatively responding to water shortage in the region.This article is part of a discussion meeting issue 'The impact of the 2015/2016 El Niño on the terrestrial tropical carbon cycle: patterns, mechanisms and implications'.
Abstract.
Author URL.
2017
Marengo JA, Nunes LH, Souza CRG, Harari J, Muller-Karger F, Greco R, Hosokawa EK, Tabuchi EK, Merrill SB, Reynolds CJ, et al (2017). A globally deployable strategy for co-development of adaptation preferences to sea-level rise: the public participation case of Santos, Brazil.
Natural Hazards,
88(1), 39-53.
Abstract:
A globally deployable strategy for co-development of adaptation preferences to sea-level rise: the public participation case of Santos, Brazil
Sea-level rise (SLR) poses a range of threats to natural and built environments in coastal zones around the world. Assessment of the risks due to exposure and sensitivity of coastal communities to coastal flooding is essential for informed decision-making. Strategies for public understanding and awareness of the tangible effects of climate change are fundamental in developing policy options. A multidisciplinary, multinational team of natural and social scientists from the USA, the UK, and Brazil developed the METROPOLE Project to evaluate how local governments may decide between adaptation options associated with SLR projections. METROPOLE developed a participatory approach in which public actors engage fully in defining the research problem and evaluating outcomes. Using a case study of the city of Santos, in Brazil, METROPOLE developed a method for evaluating risks jointly with the community, comparing ‘no-action’ to ‘adaptation’ scenarios. At the core of the analysis are estimates of economic costs of the impact of floods on urban real estate under SLR projections through 2050 and 2100. Results helped identify broad preferences and orientations in adaptation planning, which the community, including the Santos municipal government, co-developed in a joint effort with natural and social scientists.
Abstract.
Grecchi RC, Beuchle R, Shimabukuro YE, Aragao LEOC, Arai E, Simonetti D, Achard F (2017). An integrated remote sensing and GIS approach for monitoring areas affected by selective logging: a case study in northern Mato Grosso, Brazilian Amazon.
INTERNATIONAL JOURNAL OF APPLIED EARTH OBSERVATION AND GEOINFORMATION,
61, 70-80.
Author URL.
Phillips OL, Brienen RJW, Gloor E, Baker TR, Lloyd J, Lopez-Gonzalez G, Monteagudo-Mendoza A, Malhi Y, Lewis SL, Vásquez Martinez R, et al (2017). Carbon uptake by mature Amazon forests has mitigated Amazon nations' carbon emissions.
Carbon Balance and Management,
12(1).
Abstract:
Carbon uptake by mature Amazon forests has mitigated Amazon nations' carbon emissions
Background: Several independent lines of evidence suggest that Amazon forests have provided a significant carbon sink service, and also that the Amazon carbon sink in intact, mature forests may now be threatened as a result of different processes. There has however been no work done to quantify non-land-use-change forest carbon fluxes on a national basis within Amazonia, or to place these national fluxes and their possible changes in the context of the major anthropogenic carbon fluxes in the region. Here we present a first attempt to interpret results from ground-based monitoring of mature forest carbon fluxes in a biogeographically, politically, and temporally differentiated way. Specifically, using results from a large long-term network of forest plots, we estimate the Amazon biomass carbon balance over the last three decades for the different regions and nine nations of Amazonia, and evaluate the magnitude and trajectory of these differentiated balances in relation to major national anthropogenic carbon emissions. Results: the sink of carbon into mature forests has been remarkably geographically ubiquitous across Amazonia, being substantial and persistent in each of the five biogeographic regions within Amazonia. Between 1980 and 2010, it has more than mitigated the fossil fuel emissions of every single national economy, except that of Venezuela. For most nations (Bolivia, Colombia, Ecuador, French Guiana, Guyana, Peru, Suriname) the sink has probably additionally mitigated all anthropogenic carbon emissions due to Amazon deforestation and other land use change. While the sink has weakened in some regions since 2000, our analysis suggests that Amazon nations which are able to conserve large areas of natural and semi-natural landscape still contribute globally-significant carbon sequestration. Conclusions: Mature forests across all of Amazonia have contributed significantly to mitigating climate change for decades. Yet Amazon nations have not directly benefited from providing this global scale ecosystem service. We suggest that better monitoring and reporting of the carbon fluxes within mature forests, and understanding the drivers of changes in their balance, must become national, as well as international, priorities.
Abstract.
Bertani G, Wagner FH, Anderson LO, Aragão LEOC (2017). Chlorophyll fluorescence data reveals climate-related photosynthesis seasonality in Amazonian forests.
Remote Sensing,
9(12).
Abstract:
Chlorophyll fluorescence data reveals climate-related photosynthesis seasonality in Amazonian forests
Amazonia is theworld largest tropical forest, playing a key role in the global carbon cycle. Thus, understanding climate controls of photosynthetic activity in this region is critical. The establishment of the relationship between photosynthetic activity and climate has been controversial when based on conventional remote sensing-derived indices. Here, we use nine years of solar-induced chlorophyll fluorescence (ChlF) data from the Global Ozone Monitoring Experiment (GOME-2) sensor, as a direct proxy for photosynthesis, to assess the seasonal response of photosynthetic activity to solar radiation and precipitation in Amazonia. Our results suggest that 76% of photosynthesis seasonality in Amazonia is explained by seasonal variations of solar radiation. However, 13% of these forests are limited by precipitation. The combination of both radiation and precipitation drives photosynthesis in the remaining 11% of the area. Photosynthesis tends to rise only after radiation increases in 61% of the forests. Furthermore, photosynthesis peaks in the wet season in about 58% of the Amazon forest. We found that a threshold of ≈1943 mm per year can be defined as a limit for precipitation phenological dependence. With the potential increase in the frequency and intensity of extreme droughts, forests that have the photosynthetic process currently associated with radiation seasonality may shift towards a more water-limited system.
Abstract.
Wagner FH, Hérault B, Rossi V, Hilker T, Maeda EE, Sanchez A, Lyapustin AI, Galvão LS, Wang Y, Aragão LEOC, et al (2017). Climate drivers of the Amazon forest greening.
PLoS One,
12(7).
Abstract:
Climate drivers of the Amazon forest greening.
Our limited understanding of the climate controls on tropical forest seasonality is one of the biggest sources of uncertainty in modeling climate change impacts on terrestrial ecosystems. Combining leaf production, litterfall and climate observations from satellite and ground data in the Amazon forest, we show that seasonal variation in leaf production is largely triggered by climate signals, specifically, insolation increase (70.4% of the total area) and precipitation increase (29.6%). Increase of insolation drives leaf growth in the absence of water limitation. For these non-water-limited forests, the simultaneous leaf flush occurs in a sufficient proportion of the trees to be observed from space. While tropical cycles are generally defined in terms of dry or wet season, we show that for a large part of Amazonia the increase in insolation triggers the visible progress of leaf growth, just like during spring in temperate forests. The dependence of leaf growth initiation on climate seasonality may result in a higher sensitivity of these ecosystems to changes in climate than previously thought.
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Author URL.
Fonseca MG, Anderson LO, Arai E, Shimabukuro YE, Xaud HAM, Xaud MR, Madani N, Wagner FH, Aragão LEOC (2017). Climatic and anthropogenic drivers of northern Amazon fires during the 2015-2016 El Niño event.
Ecol Appl,
27(8), 2514-2527.
Abstract:
Climatic and anthropogenic drivers of northern Amazon fires during the 2015-2016 El Niño event.
The strong El Niño Southern Oscillation (ENSO) event that occurred in 2015-2016 caused extreme drought in the northern Brazilian Amazon, especially in the state of Roraima, increasing fire occurrence. Here we map the extent of precipitation and fire anomalies and quantify the effects of climatic and anthropogenic drivers on fire occurrence during the 2015-2016 dry season (from December 2015 to March 2016) in the state of Roraima. To achieve these objectives we first estimated the spatial pattern of precipitation anomalies, based on long-term data from the TRMM (Tropical Rainfall Measuring Mission), and the fire anomaly, based on MODIS (Moderate Resolution Imaging Spectroradiometer) active fire detections during the referred period. Then, we integrated climatic and anthropogenic drivers in a Maximum Entropy (MaxEnt) model to quantify fire probability, assessing (1) the model accuracy during the 2015-2016 and the 2016-2017 dry seasons; (2) the relative importance of each predictor variable on the model predictive performance; and (3) the response curves, showing how each environmental variable affects the fire probability. Approximately 59% (132,900 km2 ) of the study area was exposed to precipitation anomalies ≤-1 standard deviation (SD) in January and ~48% (~106,800 km2 ) in March. About 38% (86,200 km2 ) of the study area experienced fire anomalies ≥1 SD in at least one month between December 2015 and March 2016. The distance to roads and the direct ENSO effect on fire occurrence were the two most influential variables on model predictive performance. Despite the improvement of governmental actions of fire prevention and firefighting in Roraima since the last intense ENSO event (1997-1998), we show that fire still gets out of control in the state during extreme drought events. Our results indicate that if no prevention actions are undertaken, future road network expansion and a climate-induced increase in water stress will amplify fire occurrence in the northern Amazon, even in its humid dense forests. As an additional outcome of our analysis, we conclude that the model and the data we used may help to guide on-the-ground fire-prevention actions and firefighting planning and therefore minimize fire-related ecosystems degradation, economic losses and carbon emissions in Roraima.
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Author URL.
Sullivan MJP, Talbot J, Lewis SL, Phillips OL, Qie L, Begne SK, Chave J, Cuni-Sanchez A, Hubau W, Lopez-Gonzalez G, et al (2017). Diversity and carbon storage across the tropical forest biome.
Sci Rep,
7Abstract:
Diversity and carbon storage across the tropical forest biome.
Tropical forests are global centres of biodiversity and carbon storage. Many tropical countries aspire to protect forest to fulfil biodiversity and climate mitigation policy targets, but the conservation strategies needed to achieve these two functions depend critically on the tropical forest tree diversity-carbon storage relationship. Assessing this relationship is challenging due to the scarcity of inventories where carbon stocks in aboveground biomass and species identifications have been simultaneously and robustly quantified. Here, we compile a unique pan-tropical dataset of 360 plots located in structurally intact old-growth closed-canopy forest, surveyed using standardised methods, allowing a multi-scale evaluation of diversity-carbon relationships in tropical forests. Diversity-carbon relationships among all plots at 1 ha scale across the tropics are absent, and within continents are either weak (Asia) or absent (Amazonia, Africa). A weak positive relationship is detectable within 1 ha plots, indicating that diversity effects in tropical forests may be scale dependent. The absence of clear diversity-carbon relationships at scales relevant to conservation planning means that carbon-centred conservation strategies will inevitably miss many high diversity ecosystems. As tropical forests can have any combination of tree diversity and carbon stocks both require explicit consideration when optimising policies to manage tropical carbon and biodiversity.
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Author URL.
Jones MW, Quine TA, de Rezende CE, Dittmar T, Johnson B, Manecki M, Marques JSJ, de Aragão LEOC (2017). Do Regional Aerosols Contribute to the Riverine Export of Dissolved Black Carbon?.
Journal of Geophysical Research: Biogeosciences,
122(11), 2925-2938.
Abstract:
Do Regional Aerosols Contribute to the Riverine Export of Dissolved Black Carbon?
AbstractThe fate of black carbon (BC), a stable form of thermally altered organic carbon produced during biomass and fuel combustion, remains an area of uncertainty in the global carbon cycle. The transfer of photosynthetically derived BC into extremely long‐term oceanic storage is of particular significance and rivers are the key linkage between terrestrial sources and oceanic stores. Significant fluvial fluxes of dissolved BC to oceans result from the slow release of BC from degrading charcoal stocks; however, these fluvial fluxes may also include undetermined contributions of aerosol BC, produced by biomass and fossil fuel combustion, which are deposited in river catchments following atmospheric transport. By investigation of the Paraíba do Sul River catchment in Southeast Brazil we show that aerosol deposits can be substantial contributors to fluvial fluxes of BC. We derived spatial distributions of BC stocks within the catchment associated with soil charcoal and with aerosol from both open biomass burning and fuel combustion. We then modeled the fluvial concentrations of dissolved BC (DBC) in scenarios with varying rates of export from each stock. We analyzed the ability of each scenario to reproduce the variability in DBC concentrations measured in four data sets of river water samples collected between 2010 and 2014 and found that the best performing scenarios included a 5–18% (135–486 Mg DBC year−1) aerosol contribution. Our results suggest that aerosol deposits of BC in river catchments have a shorter residence time in catchments than charcoal BC and, therefore, contribute disproportionately (with respect to stock magnitude) toward fluvial fluxes of BC.
Abstract.
Bispo PDC, Balzter H, Malhi Y, Slik JWF, Santos JR, Rennó CD, Espírito-Santo FD, Aragão LEOC, Ximenes AC, Bispo PDC, et al (2017). Drivers of metacommunity structure diverge for common and rare Amazonian tree species.
PLoS One,
12(11).
Abstract:
Drivers of metacommunity structure diverge for common and rare Amazonian tree species.
We analysed the flora of 46 forest inventory plots (25 m x 100 m) in old growth forests from the Amazonian region to identify the role of environmental (topographic) and spatial variables (obtained using PCNM, Principal Coordinates of Neighbourhood Matrix analysis) for common and rare species. For the analyses, we used multiple partial regression to partition the specific effects of the topographic and spatial variables on the univariate data (standardised richness, total abundance and total biomass) and partial RDA (Redundancy Analysis) to partition these effects on composition (multivariate data) based on incidence, abundance and biomass. The different attributes (richness, abundance, biomass and composition based on incidence, abundance and biomass) used to study this metacommunity responded differently to environmental and spatial processes. Considering standardised richness, total abundance (univariate) and composition based on biomass, the results for common species differed from those obtained for all species. On the other hand, for total biomass (univariate) and for compositions based on incidence and abundance, there was a correspondence between the data obtained for the total community and for common species. Our data also show that in general, environmental and/or spatial components are important to explain the variability in tree communities for total and common species. However, with the exception of the total abundance, the environmental and spatial variables measured were insufficient to explain the attributes of the communities of rare species. These results indicate that predicting the attributes of rare tree species communities based on environmental and spatial variables is a substantial challenge. As the spatial component was relevant for several community attributes, our results demonstrate the importance of using a metacommunities approach when attempting to understand the main ecological processes underlying the diversity of tropical forest communities.
Abstract.
Author URL.
de Oliveira G, Brunsell NA, Moraes EC, Shimabukuro YE, Bertani G, dos Santos TV, Aragao LEOC (2017). Evaluation of MODIS-based estimates of water-use efficiency in Amazonia.
INTERNATIONAL JOURNAL OF REMOTE SENSING,
38(19), 5291-5309.
Author URL.
Trabaquini K, Galvão LS, Formaggio AR, de Aragão LEOEC (2017). Soil, land use time, and sustainable intensification of agriculture in the Brazilian Cerrado region.
Environ Monit Assess,
189(2).
Abstract:
Soil, land use time, and sustainable intensification of agriculture in the Brazilian Cerrado region.
The Brazilian Cerrado area is in rapid decline because of the expansion of modern agriculture. In this study, we used extensive field data and a 30-year chronosequence of Landsat images (1980-2010) to assess the effects of time since conversion of Cerrado into agriculture upon soil chemical attributes and soybean/corn yield in the Alto do Rio Verde watershed. We determined the rates of vegetation conversion into agriculture, the agricultural land use time since conversion, and the temporal changes in topsoil (0-20 cm soil depth) and subsurface (20-40 cm) chemical attributes of the soils. In addition, we investigated possible associations between fertilization/over-fertilization and land use history detected from the satellites. The results showed that 61.8% of the native vegetation in the Alto do Rio Verde watershed was already converted into agriculture with 31% of soils being used in agriculture for more than 30 years. While other fertilizers in cultivated soils (e.g. Ca+2, Mg+2, and P) have been compensated over time by soil management practices to keep crop yield high, large reductions in C org (38%) and N tot (29%) were observed in old cultivated areas. Furthermore, soybean and cornfields having more than 10 years of farming presented higher values of P and Mg+2 than the ideal levels necessary for plant development. Therefore, increased risks of over-fertilization of the soils and environmental contamination with these macronutrients were associated with soybean and cornfields having more than 10 years of farming, especially those with more than 30 years of agricultural land use.
Abstract.
Author URL.
de Moura YM, Galvão LS, Hilker T, Wu J, Saleska S, do Amaral CH, Nelson BW, Lopes AP, Wiedeman KK, Prohaska N, et al (2017). Spectral analysis of amazon canopy phenology during the dry season using a tower hyperspectral camera and modis observations.
ISPRS Journal of Photogrammetry and Remote Sensing,
131, 52-64.
Abstract:
Spectral analysis of amazon canopy phenology during the dry season using a tower hyperspectral camera and modis observations
The association between spectral reflectance and canopy processes remains challenging for quantifying large-scale canopy phenological cycles in tropical forests. In this study, we used a tower-mounted hyperspectral camera in an eastern Amazon forest to assess how canopy spectral signals of three species are linked with phenological processes in the 2012 dry season. We explored different approaches to disentangle the spectral components of canopy phenology processes and analyze their variations over time using 17 images acquired by the camera. The methods included linear spectral mixture analysis (SMA); principal component analysis (PCA); continuum removal (CR); and first-order derivative analysis. In addition, three vegetation indices potentially sensitive to leaf flushing, leaf loss and leaf area index (LAI) were calculated: the Enhanced Vegetation Index (EVI), Normalized Difference Vegetation Index (NDVI) and the entitled Green-Red Normalized Difference (GRND) index. We inspected also the consistency of the camera observations using Moderate Resolution Imaging Spectroradiometer (MODIS) and available phenological data on new leaf production and LAI of young, mature and old leaves simulated by a leaf demography-ontogeny model. The results showed a diversity of phenological responses during the 2012 dry season with related changes in canopy structure and greenness values. Because of the differences in timing and intensity of leaf flushing and leaf shedding, Erisma uncinatum, Manilkara huberi and Chamaecrista xinguensis presented different green vegetation (GV) and non-photosynthetic vegetation (NPV) SMA fractions; distinct PCA scores; changes in depth, width and area of the 681-nm chlorophyll absorption band; and variations over time in the EVI, GRND and NDVI. At the end of dry season, GV increased for Erisma uncinatum, while NPV increased for Chamaecrista xinguensis. For Manilkara huberi, the NPV first increased in the beginning of August and then decreased toward September with new foliage. Variations in red-edge position were not statistically significant between the species and across dates at the 95% confidence level. The camera data were affected by view-illumination effects, which reduced the SMA shade fraction over time. When MODIS data were corrected for these effects using the Multi-Angle Implementation of Atmospheric Correction Algorithm (MAIAC), we observed an EVI increase toward September that closely tracked the modeled LAI of mature leaves (3–5 months). Compared to the EVI, the GRND was a better indicator of leaf flushing because the modeled production of new leaves peaked in August and then declined in September following the GRND closely. While the EVI was more related to changes in mature leaf area, the GRND was more associated with new leaf flushing.
Abstract.
Malhi Y, Girardin CAJ, Goldsmith GR, Doughty CE, Salinas N, Metcalfe DB, Huaraca Huasco W, Silva-Espejo JE, Del Aguilla-Pasquell J, Farfán Amézquita F, et al (2017). The variation of productivity and its allocation along a tropical elevation gradient: a whole carbon budget perspective.
New Phytol,
214(3), 1019-1032.
Abstract:
The variation of productivity and its allocation along a tropical elevation gradient: a whole carbon budget perspective.
Why do forest productivity and biomass decline with elevation? to address this question, research to date generally has focused on correlative approaches describing changes in woody growth and biomass with elevation. We present a novel, mechanistic approach to this question by quantifying the autotrophic carbon budget in 16 forest plots along a 3300 m elevation transect in Peru. Low growth rates at high elevations appear primarily driven by low gross primary productivity (GPP), with little shift in either carbon use efficiency (CUE) or allocation of net primary productivity (NPP) between wood, fine roots and canopy. The lack of trend in CUE implies that the proportion of photosynthate allocated to autotrophic respiration is not sensitive to temperature. Rather than a gradual linear decline in productivity, there is some limited but nonconclusive evidence of a sharp transition in NPP between submontane and montane forests, which may be caused by cloud immersion effects within the cloud forest zone. Leaf-level photosynthetic parameters do not decline with elevation, implying that nutrient limitation does not restrict photosynthesis at high elevations. Our data demonstrate the potential of whole carbon budget perspectives to provide a deeper understanding of controls on ecosystem functioning and carbon cycling.
Abstract.
Author URL.
Hilker T, Galvao LS, Aragao LEOC, de Moura YM, do Amaral CH, Lyapustin AI, Wu J, Albert LP, Ferreira MJ, Anderson LO, et al (2017). Vegetation chlorophyll estimates in the Amazon from multi-angle MODIS observations and canopy reflectance model.
INTERNATIONAL JOURNAL OF APPLIED EARTH OBSERVATION AND GEOINFORMATION,
58, 278-287.
Author URL.
2016
Feldpausch TR, Phillips OL, Brienen RJW, Gloor E, Lloyd J, Lopez-Gonzalez G, Monteagudo-Mendoza A, Malhi Y, Alarcón A, Álvarez Dávila E, et al (2016). Amazon forest response to repeated droughts. Global Biogeochemical Cycles, 30(7), 964-982.
Barlow J, Lennox GD, Ferreira J, Berenguer E, Lees AC, Mac Nally R, Thomson JR, Ferraz SFDB, Louzada J, Oliveira VHF, et al (2016). Anthropogenic disturbance in tropical forests can double biodiversity loss from deforestation.
Nature,
535(7610), 144-147.
Abstract:
Anthropogenic disturbance in tropical forests can double biodiversity loss from deforestation.
Concerted political attention has focused on reducing deforestation, and this remains the cornerstone of most biodiversity conservation strategies. However, maintaining forest cover may not reduce anthropogenic forest disturbances, which are rarely considered in conservation programmes. These disturbances occur both within forests, including selective logging and wildfires, and at the landscape level, through edge, area and isolation effects. Until now, the combined effect of anthropogenic disturbance on the conservation value of remnant primary forests has remained unknown, making it impossible to assess the relative importance of forest disturbance and forest loss. Here we address these knowledge gaps using a large data set of plants, birds and dung beetles (1,538, 460 and 156 species, respectively) sampled in 36 catchments in the Brazilian state of Pará. Catchments retaining more than 69–80% forest cover lost more conservation value from disturbance than from forest loss. For example, a 20% loss of primary forest, the maximum level of deforestation allowed on Amazonian properties under Brazil’s Forest Code, resulted in a 39–54% loss of conservation value: 96–171% more than expected without considering disturbance effects. We extrapolated the disturbance-mediated loss of conservation value throughout Pará, which covers 25% of the Brazilian Amazon. Although disturbed forests retained considerable conservation value compared with deforested areas, the toll of disturbance outside Pará’s strictly protected areas is equivalent to the loss of 92,000–139,000 km2 of primary forest. Even this lowest estimate is greater than the area deforested across the entire Brazilian Amazon between 2006 and 2015 (ref. 10). Species distribution models showed that both landscape and within-forest disturbances contributed to biodiversity loss, with the greatest negative effects on species of high conservation and functional value. These results demonstrate an urgent need for policy interventions that go beyond the maintenance of forest cover to safeguard the hyper-diversity of tropical forest ecosystems.
Abstract.
Author URL.
Wagner FH, Hérault B, Bonal D, Stahl C, Anderson LO, Baker TR, Sebastian Becker G, Beeckman H, Boanerges Souza D, Cesar Botosso P, et al (2016). Climate seasonality limits leaf carbon assimilation and wood productivity in tropical forests.
Biogeosciences,
13(8), 2537-2562.
Abstract:
Climate seasonality limits leaf carbon assimilation and wood productivity in tropical forests
The seasonal climate drivers of the carbon cycle in tropical forests remain poorly known, although these forests account for more carbon assimilation and storage than any other terrestrial ecosystem. Based on a unique combination of seasonal pan-tropical data sets from 89 experimental sites (68 include aboveground wood productivity measurements and 35 litter productivity measurements), their associated canopy photosynthetic capacity (enhanced vegetation index, EVI) and climate, we ask how carbon assimilation and aboveground allocation are related to climate seasonality in tropical forests and how they interact in the seasonal carbon cycle. We found that canopy photosynthetic capacity seasonality responds positively to precipitation when rainfall is. & lt; 2000ĝ€-mmĝ€-yrĝ'1 (water-limited forests) and to radiation otherwise (light-limited forests). On the other hand, independent of climate limitations, wood productivity and litterfall are driven by seasonal variation in precipitation and evapotranspiration, respectively. Consequently, light-limited forests present an asynchronism between canopy photosynthetic capacity and wood productivity. First-order control by precipitation likely indicates a decrease in tropical forest productivity in a drier climate in water-limited forest, and in current light-limited forest with future rainfall. & lt; 2000ĝ€-mmĝ€-yrĝ'1. Author(s) 2016.
Abstract.
Maeda EE, Moura YM, Wagner F, Hilker T, Lyapustin AI, Wang Y, Chave J, Mõttus M, Aragão LEOC, Shimabukuro Y, et al (2016). Consistency of vegetation index seasonality across the Amazon rainforest.
International Journal of Applied Earth Observation and Geoinformation,
52, 42-53.
Abstract:
Consistency of vegetation index seasonality across the Amazon rainforest
Vegetation indices (VIs) calculated from remotely sensed reflectance are widely used tools for characterizing the extent and status of vegetated areas. Recently, however, their capability to monitor the Amazon forest phenology has been intensely scrutinized. In this study, we analyze the consistency of VIs seasonal patterns obtained from two MODIS products: the Collection 5 BRDF product (MCD43) and the Multi-Angle Implementation of Atmospheric Correction algorithm (MAIAC). The spatio-temporal patterns of the VIs were also compared with field measured leaf litterfall, gross ecosystem productivity and active microwave data. Our results show that significant seasonal patterns are observed in all VIs after the removal of view-illumination effects and cloud contamination. However, we demonstrate inconsistencies in the characteristics of seasonal patterns between different VIs and MODIS products. We demonstrate that differences in the original reflectance band values form a major source of discrepancy between MODIS VI products. The MAIAC atmospheric correction algorithm significantly reduces noise signals in the red and blue bands. Another important source of discrepancy is caused by differences in the availability of clear-sky data, as the MAIAC product allows increased availability of valid pixels in the equatorial Amazon. Finally, differences in VIs seasonal patterns were also caused by MODIS collection 5 calibration degradation. The correlation of remote sensing and field data also varied spatially, leading to different temporal offsets between VIs, active microwave and field measured data. We conclude that recent improvements in the MAIAC product have led to changes in the characteristics of spatio-temporal patterns of VIs seasonality across the Amazon forest, when compared to the MCD43 product. Nevertheless, despite improved quality and reduced uncertainties in the MAIAC product, a robust biophysical interpretation of VIs seasonality is still missing.
Abstract.
Navarrete D, Sitch S, Aragão LEOC, Pedroni L (2016). Conversion from forests to pastures in the Colombian Amazon leads to contrasting soil carbon dynamics depending on land management practices.
Glob Chang Biol,
22(10), 3503-3517.
Abstract:
Conversion from forests to pastures in the Colombian Amazon leads to contrasting soil carbon dynamics depending on land management practices.
Strategies to mitigate climate change by reducing deforestation and forest degradation (e.g. REDD+) require country- or region-specific information on temporal changes in forest carbon (C) pools to develop accurate emission factors. The soil C pool is one of the most important C reservoirs, but is rarely included in national forest reference emission levels due to a lack of data. Here, we present the soil organic C (SOC) dynamics along 20 years of forest-to-pasture conversion in two subregions with different management practices during pasture establishment in the Colombian Amazon: high-grazing intensity (HG) and low-grazing intensity (LG) subregions. We determined the pattern of SOC change resulting from the conversion from forest (C3 plants) to pasture (C4 plants) by analysing total SOC stocks and the natural abundance of the stable isotopes (13) C along two 20-year chronosequences identified in each subregion. We also analysed soil N stocks and the natural abundance of (15) N during pasture establishment. In general, total SOC stocks at 30 cm depth in the forest were similar for both subregions, with an average of 47.1 ± 1.8 Mg C ha(-1) in HG and 48.7 ± 3.1 Mg C ha(-1) in LG. However, 20 years after forest-to-pasture conversion SOC in HG decreased by 20%, whereas in LG SOC increased by 41%. This net SOC decrease in HG was due to a larger reduction in C3-derived input and to a comparatively smaller increase in C4-derived C input. In LG both C3- and C4-derived C input increased along the chronosequence. N stocks were generally similar in both subregions and soil N stock changes during pasture establishment were correlated with SOC changes. These results emphasize the importance of management practices involving low-grazing intensity in cattle activities to preserve SOC stocks and to reduce C emissions after land-cover change from forest to pasture in the Colombian Amazon.
Abstract.
Author URL.
Navarrete D, Sitch S, Aragão LEOC, Pedroni L, Duque A (2016). Conversion from forests to pastures in the Colombian Amazon leads to differences in dead wood dynamics depending on land management practices.
J Environ Manage,
171, 42-51.
Abstract:
Conversion from forests to pastures in the Colombian Amazon leads to differences in dead wood dynamics depending on land management practices.
Dead wood, composed of coarse standing and fallen woody debris (CWD), is an important carbon (C) pool in tropical forests and its accounting is needed to reduce uncertainties within the strategies to mitigate climate change by reducing deforestation and forest degradation (REDD+). To date, information on CWD stocks in tropical forests is scarce and effects of land-cover conversion and land management practices on CWD dynamics remain largely unexplored. Here we present estimates on CWD stocks in primary forests in the Colombian Amazon and their dynamics along 20 years of forest-to-pasture conversion in two sub-regions with different management practices during pasture establishment: high-grazing intensity (HG) and low-grazing intensity (LG) sub-regions. Two 20-year-old chronosequences describing the forest-to-pasture conversion were identified in both sub-regions. The line-intersect and the plot-based methods were used to estimate fallen and standing CWD stocks, respectively. Total necromass in primary forests was similar between both sub-regions (35.6 ± 5.8 Mg ha(-1) in HG and 37.0 ± 7.4 Mg ha(-1) in LG). An increase of ∼124% in CWD stocks followed by a reduction to values close to those at the intact forests were registered after slash-and-burn practice was implemented in both sub-regions during the first two years of forest-to-pasture conversion. Implementation of machinery after using fire in HG pastures led to a reduction of 82% in CWD stocks during the second and fifth years of pasture establishment, compared to a decrease of 41% during the same period in LG where mechanization is not implemented. Finally, average necromass 20 years after forest-to-pasture conversion decreased to 3.5 ± 1.4 Mg ha(-1) in HG and 9.3 ± 3.5 Mg ha(-1) in LG, representing a total reduction of between 90% and 75% in each sub-region, respectively. These results highlight the importance of low-grazing intensity management practices during ranching activities in the Colombian Amazon to reduce C emissions associated with land-cover change from forest to pasture.
Abstract.
Author URL.
Coelho de Souza F, Dexter KG, Phillips OL, Brienen RJW, Chave J, Galbraith DR, Lopez Gonzalez G, Monteagudo Mendoza A, Pennington RT, Poorter L, et al (2016). Evolutionary heritage influences Amazon tree ecology.
Proc Biol Sci,
283(1844).
Abstract:
Evolutionary heritage influences Amazon tree ecology.
Lineages tend to retain ecological characteristics of their ancestors through time. However, for some traits, selection during evolutionary history may have also played a role in determining trait values. To address the relative importance of these processes requires large-scale quantification of traits and evolutionary relationships among species. The Amazonian tree flora comprises a high diversity of angiosperm lineages and species with widely differing life-history characteristics, providing an excellent system to investigate the combined influences of evolutionary heritage and selection in determining trait variation. We used trait data related to the major axes of life-history variation among tropical trees (e.g. growth and mortality rates) from 577 inventory plots in closed-canopy forest, mapped onto a phylogenetic hypothesis spanning more than 300 genera including all major angiosperm clades to test for evolutionary constraints on traits. We found significant phylogenetic signal (PS) for all traits, consistent with evolutionarily related genera having more similar characteristics than expected by chance. Although there is also evidence for repeated evolution of pioneer and shade tolerant life-history strategies within independent lineages, the existence of significant PS allows clearer predictions of the links between evolutionary diversity, ecosystem function and the response of tropical forests to global change.
Abstract.
Author URL.
Marengo JA, Aragão LEOC, Cox PM, Betts R, Costa D, Kaye N, Smith LT, Alves LM, Reis V (2016). Impacts of climate extremes in Brazil the development of a web platform for understanding long-term sustainability of ecosystems and human health in amazonia (pulse-Brazil).
Bulletin of the American Meteorological Society,
97(8), 1341-1346.
Abstract:
Impacts of climate extremes in Brazil the development of a web platform for understanding long-term sustainability of ecosystems and human health in amazonia (pulse-Brazil)
Impacts of climate extremes in Brazil led to the development of a web platform for understanding long-term sustainability of ecosystems and human health in Amazonia. It was difficult to synthesize all available information in a comprehensive structure that enables different sectors of the society to understand the consequences of extreme events and support timely decision making. In recognition of this problem of data compilation, management, and visualization, a consortium of cross-disciplinary Brazilian and UK scientists, encompassing environmental, human health, and modeling backgrounds, was selected under the umbrella of the International Opportunities Fund, and jointly funded by the São Paulo Science Foundation (FAPESP) in Brazil and the Natural Environment Research Council (NERC) in the United Kingdom to enhance the knowledge in environmental sciences directly applicable to policy decisions. A key result of this cooperation was the ongoing development of PULSE-Brazil, a Platform for Understanding Long-term Sustainability of Ecosystems and human health, specifically applied to Brazil.
Abstract.
Lyapustin AI, Coops NC, Hall FG, Tucker CJ, Sellers PJ, Galvao LS, Aragao LEOC, Anderson LO, Nichol CJ, Waring RH, et al (2016). In Memorium: Thomas Hilker Obituary.
REMOTE SENSING,
8(10).
Author URL.
Devisscher T, Anderson LO, Aragão LEOC, Galván L, Malhi Y (2016). Increased Wildfire Risk Driven by Climate and Development Interactions in the Bolivian Chiquitania, Southern Amazonia.
PLoS One,
11(9).
Abstract:
Increased Wildfire Risk Driven by Climate and Development Interactions in the Bolivian Chiquitania, Southern Amazonia.
Wildfires are becoming increasingly dominant in tropical landscapes due to reinforcing feedbacks between land cover change and more severe dry conditions. This study focused on the Bolivian Chiquitania, a region located at the southern edge of Amazonia. The extensive, unique and well-conserved tropical dry forest in this region is susceptible to wildfires due to a marked seasonality. We used a novel approach to assess fire risk at the regional level driven by different development trajectories interacting with changing climatic conditions. Possible future risk scenarios were simulated using maximum entropy modelling with presence-only data, combining land cover, anthropogenic and climatic variables. We found that important determinants of fire risk in the region are distance to roads, recent deforestation and density of human settlements. Severely dry conditions alone increased the area of high fire risk by 69%, affecting all categories of land use and land cover. Interactions between extreme dry conditions and rapid frontier expansion further increased fire risk, resulting in potential biomass loss of 2.44±0.8 Tg in high risk area, about 1.8 times higher than the estimates for the 2010 drought. These interactions showed particularly high fire risk in land used for 'extensive cattle ranching', 'agro-silvopastoral use' and 'intensive cattle ranching and agriculture'. These findings have serious implications for subsistence activities and the economy in the Chiquitania, which greatly depend on the forestry, agriculture and livestock sectors. Results are particularly concerning if considering the current development policies promoting frontier expansion. Departmental protected areas inhibited wildfires when strategically established in areas of high risk, even under drought conditions. However, further research is needed to assess their effectiveness accounting for more specific contextual factors. This novel and simple modelling approach can inform fire and land management decisions in the Chiquitania and other tropical forest landscapes to better anticipate and manage large wildfires in the future.
Abstract.
Author URL.
Aguiar APD, Vieira ICG, Assis TO, Dalla-Nora EL, Toledo PM, Santos-Junior RAO, Batistella M, Coelho AS, Savaget EK, Aragão LEOC, et al (2016). Land use change emission scenarios: anticipating a forest transition process in the Brazilian Amazon.
Glob Chang Biol,
22(5), 1821-1840.
Abstract:
Land use change emission scenarios: anticipating a forest transition process in the Brazilian Amazon.
Following an intense occupation process that was initiated in the 1960s, deforestation rates in the Brazilian Amazon have decreased significantly since 2004, stabilizing around 6000 km(2) yr(-1) in the last 5 years. A convergence of conditions contributed to this, including the creation of protected areas, the use of effective monitoring systems, and credit restriction mechanisms. Nevertheless, other threats remain, including the rapidly expanding global markets for agricultural commodities, large-scale transportation and energy infrastructure projects, and weak institutions. We propose three updated qualitative and quantitative land-use scenarios for the Brazilian Amazon, including a normative 'Sustainability' scenario in which we envision major socio-economic, institutional, and environmental achievements in the region. We developed an innovative spatially explicit modelling approach capable of representing alternative pathways of the clear-cut deforestation, secondary vegetation dynamics, and the old-growth forest degradation. We use the computational models to estimate net deforestation-driven carbon emissions for the different scenarios. The region would become a sink of carbon after 2020 in a scenario of residual deforestation (~1000 km(2) yr(-1)) and a change in the current dynamics of the secondary vegetation - in a forest transition scenario. However, our results also show that the continuation of the current situation of relatively low deforestation rates and short life cycle of the secondary vegetation would maintain the region as a source of CO2 - even if a large portion of the deforested area is covered by secondary vegetation. In relation to the old-growth forest degradation process, we estimated average gross emission corresponding to 47% of the clear-cut deforestation from 2007 to 2013 (using the DEGRAD system data), although the aggregate effects of the postdisturbance regeneration can partially offset these emissions. Both processes (secondary vegetation and forest degradation) need to be better understood as they potentially will play a decisive role in the future regional carbon balance.
Abstract.
Author URL.
Fonseca MG, Aragão LEOC, Lima A, Shimabukuro YE, Arai E, Anderson LO (2016). Modelling fire probability in the Brazilian Amazon using the maximum entropy method.
International Journal of Wildland Fire,
25(9), 955-969.
Abstract:
Modelling fire probability in the Brazilian Amazon using the maximum entropy method
Fires are both a cause and consequence of important changes in the Amazon region. The development and implementation of better fire management practices and firefighting strategies are important steps to reduce the Amazon ecosystems' degradation and carbon emissions from land-use change in the region. We extended the application of the maximum entropy method (MaxEnt) to model fire occurrence probability in the Brazilian Amazon on a monthly basis during the 2008 and 2010 fire seasons using fire detection data derived from satellite images. Predictor variables included climatic variables, inhabited and uninhabited protected areas and land-use change maps. Model fit was assessed using the area under the curve (AUC) value (threshold-independent analysis), binomial tests and model sensitivity and specificity (threshold-dependent analysis). Both threshold-independent (AUC≤0.919±0.004) and threshold-dependent evaluation indicate satisfactory model performance. Pasture, annual deforestation and secondary vegetation are the most effective variables for predicting the distribution of the occurrence data. Our results show that MaxEnt may become an important tool to guide on-the-ground decisions on fire prevention actions and firefighting planning more effectively and thus to minimise forest degradation and carbon loss from forest fires in Amazonian ecosystems.
Abstract.
Sato LY, Gomes VCF, Shimabukuro YE, Keller M, Arai E, dos-Santos MN, Brown IF, de Aragão LEOEC (2016). Post-fire changes in forest biomass retrieved by airborne LiDAR in Amazonia.
Remote Sensing,
8(10).
Abstract:
Post-fire changes in forest biomass retrieved by airborne LiDAR in Amazonia
Fire is one of the main factors directly impacting Amazonian forest biomass and dynamics. Because of Amazonia's large geographical extent, remote sensing techniques are required for comprehensively assessing forest fire impacts at the landscape level. In this context, Light Detection and Ranging (LiDAR) stands out as a technology capable of retrieving direct measurements of vegetation vertical arrangement, which can be directly associated with aboveground biomass. This work aims, for the first time, to quantify post-fire changes in forest canopy height and biomass using airborne LiDAR in western Amazonia. For this, the present study evaluated four areas located in the state of Acre, called Rio Branco, Humaitá, Bonal and Talismã. Rio Branco and Humaitá burned in 2005 and Bonal and Talismã burned in 2010. In these areas, we inventoried a total of 25 plots (0.25 ha each) in 2014. Humaitá and Talismã are located in an open forest with bamboo and Bonal and Rio Branco are located in a dense forest. Our results showed that even ten years after the fire event, there was no complete recovery of the height and biomass of the burned areas (p < 0.05). The percentage difference in height between control and burned sites was 2.23% for Rio Branco, 9.26% for Humaitá, 10.03% for Talismã and 20.25% for Bonal. All burned sites had significantly lower biomass values than control sites. In Rio Branco (ten years after fire), Humaitá (nine years after fire), Bonal (four years after fire) and Talismã (five years after fire) biomass was 6.71%, 13.66%, 17.89% and 22.69% lower than control sites, respectively. The total amount of biomass lost for the studied sites was 16,706.3 Mg, with an average loss of 4176.6 Mg for sites burned in 2005 and 2890 Mg for sites burned in 2010, with an average loss of 3615 Mg. Fire impact associated with tree mortality was clearly detected using LiDAR data up to ten years after the fire event. This study indicates that fire disturbance in the Amazon region can cause persistent above-ground biomass loss and subsequent reduction of forest carbon stocks. Continuous monitoring of burned forests is required for depicting the long-term recovery trajectory of fire-affected Amazonian forests.
Abstract.
Vedovato LB, Fonseca MG, Arai E, Anderson LO, Aragão LEOC (2016). The extent of 2014 forest fragmentation in the Brazilian Amazon.
Regional Environmental Change,
16(8), 2485-2490.
Abstract:
The extent of 2014 forest fragmentation in the Brazilian Amazon
Despite a 79% reduction in deforestation rates since 2004 in the Brazilian Amazon, the current gross forest loss of 6207 km2 year−1 remains significant, promoting continuous habitat fragmentation. This study assessed the status of forest fragmentation in 2014 across the Brazilian Amazon applying a Morphological Spatial Pattern Analysis (MSPA). Our analysis provides the first 60-m-resolution fragmentation map for the entire Brazilian Amazon, including not only the commonly evaluated fragmentation classes such as core, edge and islet, but also four specific metrics measuring the effects of fragmentation on forest patterns (perforation, bridge, loop and forest branches). Areas of intense forest fragmentation were detected not only along the “arc of deforestation” of the eastern and southern Brazilian Amazon but in other regions as well. Considering a 1020-m edge width, we found that 28% (~891,000 km2) of the remnant forest was in non-core classes. Among these classes, bridge (i.e. forest corridors too narrow to contain core area) was the most representative (10.8%). The proportion of core area varied greatly among states, from 82.8% of the remaining forest in Amazonas to 26.1 and 13.5% in Maranhão and Tocantins, respectively. The detailed diagnosis of tropical forest fragmentation is a critical step for proposing solutions to maintain the stability of tropical forest services, including carbon storage, water and nutrient cycling, and biodiversity.
Abstract.
Scaranello MAS, Castro BS, Farias RA, Vieira SA, Alves LF, Robortella HS, Aragão LEOC (2016). The role of stand structure and palm abundance in predicting above-ground biomass at local scale in southern Amazonia.
Plant Ecology and Diversity,
9(4), 409-420.
Abstract:
The role of stand structure and palm abundance in predicting above-ground biomass at local scale in southern Amazonia
Background: Most work in Amazonia has concentrated on dense lowland evergreen rain forest, a vegetation type with >40% cover. Large parts of southern Amazonia are covered by open evergreen lowland rain forest, physiognomically dominated by high abundance of palms. This vegetation type has received relatively little attention so far. Understanding the key predictors of above-ground biomass (AGB) across scales is important to accurately quantify the impacts of land cover change on the terrestrial carbon budget. Aims: We assessed the structure of southern Amazonian forests, Brazil, to quantify the relative importance of variation in AGB caused by the abundance/density of palm species and by forest structure. Methods: We stratified the landscape into homogeneous units in terms of vegetation types and elevation for using as a guide for plot establishment. We used the variation partitioning technique to decompose the relative contribution of forest structure and palm abundance. Results: the AGBcommunity (including trees, palms and lianas) and AGBtree (excluding palms and lianas) significantly decreased with increasing abundance of palms. The Attalea speciosa, a large-leaved palm species, was the most important for explaining the variance of AGB. The total variance of AGBtree was partially explained by a redundant effect of A. speciosa and trees (28%) and by trees alone (62%), based on models of basal area. The redundant effect, alongside with additional analyses, indicated (1) competition between A. speciosa and small trees and (2) covariation between A. speciosa and large trees. Conclusions: the abundance of palms plays a minor but significant role in predicting the AGB at the local scale in southern Amazonia.
Abstract.
Stark SC, Breshears DD, Garcia ES, Law DJ, Minor DM, Saleska SR, Swann ALS, Villegas JC, Aragão LEOC, Bella EM, et al (2016). Toward accounting for ecoclimate teleconnections: intra- and inter-continental consequences of altered energy balance after vegetation change.
Landscape Ecology,
31(1), 181-194.
Abstract:
Toward accounting for ecoclimate teleconnections: intra- and inter-continental consequences of altered energy balance after vegetation change
Context: Vegetation is projected to continue to undergo major structural changes in coming decades due to land conversion and climate change, including widespread forest die-offs. These vegetation changes are important not only for their local or regional climatic effects, but also because they can affect climate and subsequently vegetation in other regions or continents through “ecoclimate teleconnections”. Objectives: We propose that ecoclimate teleconnections are a fundamental link among regions within and across continents, and are central to advancing large-scale macrosystems ecology. Methods and results: We illustrate potential ecoclimate teleconnections in a bounding simulation that assumes complete tree cover loss in western North America due to tree die-off, and which predicts subsequent drying and reduced net primary productivity in other areas of North America, the Amazon and elsewhere. Central to accurately modeling such ecoclimate teleconnections is characterizing how vegetation change alters albedo and other components of the land-surface energy balance and then scales up to impact the climate system. We introduce a framework for rapid field-based characterization of vegetation structure and energy balance to help address this challenge. Conclusions: Ecoclimate teleconnections are likely a fundamental aspect of macrosystems ecology needed to account for alterations to large-scale atmospheric-ecological couplings in response to vegetation change, including deforestation, afforestation and die-off.
Abstract.
Bustamante MMC, Roitman I, Aide TM, Alencar A, Anderson LO, Aragão L, Asner GP, Barlow J, Berenguer E, Chambers J, et al (2016). Toward an integrated monitoring framework to assess the effects of tropical forest degradation and recovery on carbon stocks and biodiversity.
Glob Chang Biol,
22(1), 92-109.
Abstract:
Toward an integrated monitoring framework to assess the effects of tropical forest degradation and recovery on carbon stocks and biodiversity.
Tropical forests harbor a significant portion of global biodiversity and are a critical component of the climate system. Reducing deforestation and forest degradation contributes to global climate-change mitigation efforts, yet emissions and removals from forest dynamics are still poorly quantified. We reviewed the main challenges to estimate changes in carbon stocks and biodiversity due to degradation and recovery of tropical forests, focusing on three main areas: (1) the combination of field surveys and remote sensing; (2) evaluation of biodiversity and carbon values under a unified strategy; and (3) research efforts needed to understand and quantify forest degradation and recovery. The improvement of models and estimates of changes of forest carbon can foster process-oriented monitoring of forest dynamics, including different variables and using spatially explicit algorithms that account for regional and local differences, such as variation in climate, soil, nutrient content, topography, biodiversity, disturbance history, recovery pathways, and socioeconomic factors. Generating the data for these models requires affordable large-scale remote-sensing tools associated with a robust network of field plots that can generate spatially explicit information on a range of variables through time. By combining ecosystem models, multiscale remote sensing, and networks of field plots, we will be able to evaluate forest degradation and recovery and their interactions with biodiversity and carbon cycling. Improving monitoring strategies will allow a better understanding of the role of forest dynamics in climate-change mitigation, adaptation, and carbon cycle feedbacks, thereby reducing uncertainties in models of the key processes in the carbon cycle, including their impacts on biodiversity, which are fundamental to support forest governance policies, such as Reducing Emissions from Deforestation and Forest Degradation.
Abstract.
Author URL.
de Oliveira G, Brunsell NA, Moraes EC, Bertani G, Dos Santos TV, Shimabukuro YE, Aragão LEOC (2016). Use of MODIS Sensor Images Combined with Reanalysis Products to Retrieve Net Radiation in Amazonia.
Sensors (Basel),
16(7).
Abstract:
Use of MODIS Sensor Images Combined with Reanalysis Products to Retrieve Net Radiation in Amazonia.
In the Amazon region, the estimation of radiation fluxes through remote sensing techniques is hindered by the lack of ground measurements required as input in the models, as well as the difficulty to obtain cloud-free images. Here, we assess an approach to estimate net radiation (Rn) and its components under all-sky conditions for the Amazon region through the Surface Energy Balance Algorithm for Land (SEBAL) model utilizing only remote sensing and reanalysis data. The study period comprised six years, between January 2001-December 2006, and images from MODIS sensor aboard the Terra satellite and GLDAS reanalysis products were utilized. The estimates were evaluated with flux tower measurements within the Large-Scale Biosphere-Atmosphere Experiment in Amazonia (LBA) project. Comparison between estimates obtained by the proposed method and observations from LBA towers showed errors between 12.5% and 16.4% and 11.3% and 15.9% for instantaneous and daily Rn, respectively. Our approach was adequate to minimize the problem related to strong cloudiness over the region and allowed to map consistently the spatial distribution of net radiation components in Amazonia. We conclude that the integration of reanalysis products and satellite data, eliminating the need for surface measurements as input model, was a useful proposition for the spatialization of the radiation fluxes in the Amazon region, which may serve as input information needed by algorithms that aim to determine evapotranspiration, the most important component of the Amazon hydrological balance.
Abstract.
Author URL.
Johnson MO, Galbraith D, Gloor M, De Deurwaerder H, Guimberteau M, Rammig A, Thonicke K, Verbeeck H, von Randow C, Monteagudo A, et al (2016). Variation in stem mortality rates determines patterns of above-ground biomass in Amazonian forests: implications for dynamic global vegetation models.
Glob Chang Biol,
22(12), 3996-4013.
Abstract:
Variation in stem mortality rates determines patterns of above-ground biomass in Amazonian forests: implications for dynamic global vegetation models.
Understanding the processes that determine above-ground biomass (AGB) in Amazonian forests is important for predicting the sensitivity of these ecosystems to environmental change and for designing and evaluating dynamic global vegetation models (DGVMs). AGB is determined by inputs from woody productivity [woody net primary productivity (NPP)] and the rate at which carbon is lost through tree mortality. Here, we test whether two direct metrics of tree mortality (the absolute rate of woody biomass loss and the rate of stem mortality) and/or woody NPP, control variation in AGB among 167 plots in intact forest across Amazonia. We then compare these relationships and the observed variation in AGB and woody NPP with the predictions of four DGVMs. The observations show that stem mortality rates, rather than absolute rates of woody biomass loss, are the most important predictor of AGB, which is consistent with the importance of stand size structure for determining spatial variation in AGB. The relationship between stem mortality rates and AGB varies among different regions of Amazonia, indicating that variation in wood density and height/diameter relationships also influences AGB. In contrast to previous findings, we find that woody NPP is not correlated with stem mortality rates and is weakly positively correlated with AGB. Across the four models, basin-wide average AGB is similar to the mean of the observations. However, the models consistently overestimate woody NPP and poorly represent the spatial patterns of both AGB and woody NPP estimated using plot data. In marked contrast to the observations, DGVMs typically show strong positive relationships between woody NPP and AGB. Resolving these differences will require incorporating forest size structure, mechanistic models of stem mortality and variation in functional composition in DGVMs.
Abstract.
Author URL.
2015
Berenguer E, Gardner TA, Ferreira J, Aragão LEOC, Camargo PB, Cerri CE, Durigan M, Oliveira Junior RC, Vieira ICG, Barlow J, et al (2015). Developing Cost-Effective Field Assessments of Carbon Stocks in Human-Modified Tropical Forests.
PLoS One,
10(8).
Abstract:
Developing Cost-Effective Field Assessments of Carbon Stocks in Human-Modified Tropical Forests.
Across the tropics, there is a growing financial investment in activities that aim to reduce emissions from deforestation and forest degradation, such as REDD+. However, most tropical countries lack on-the-ground capacity to conduct reliable and replicable assessments of forest carbon stocks, undermining their ability to secure long-term carbon finance for forest conservation programs. Clear guidance on how to reduce the monetary and time costs of field assessments of forest carbon can help tropical countries to overcome this capacity gap. Here we provide such guidance for cost-effective one-off field assessments of forest carbon stocks. We sampled a total of eight components from four different carbon pools (i.e. aboveground, dead wood, litter and soil) in 224 study plots distributed across two regions of eastern Amazon. For each component we estimated survey costs, contribution to total forest carbon stocks and sensitivity to disturbance. Sampling costs varied thirty-one-fold between the most expensive component, soil, and the least, leaf litter. Large live stems (≥10 cm DBH), which represented only 15% of the overall sampling costs, was by far the most important component to be assessed, as it stores the largest amount of carbon and is highly sensitive to disturbance. If large stems are not taxonomically identified, costs can be reduced by a further 51%, while incurring an error in aboveground carbon estimates of only 5% in primary forests, but 31% in secondary forests. For rapid assessments, necessary to help prioritize locations for carbon- conservation activities, sampling of stems ≥20cm DBH without taxonomic identification can predict with confidence (R2 = 0.85) whether an area is relatively carbon-rich or carbon-poor-an approach that is 74% cheaper than sampling and identifying all the stems ≥10cm DBH. We use these results to evaluate the reliability of forest carbon stock estimates provided by the IPCC and FAO when applied to human-modified forests, and to highlight areas where cost savings in carbon stock assessments could be most easily made.
Abstract.
Author URL.
Anderson LO, Aragão LEOC, Gloor M, Arai E, Adami M, Saatchi SS, Malhi Y, Shimabukuro YE, Barlow J, Berenguer E, et al (2015). Disentangling the contribution of multiple land covers to fire-mediated carbon emissions in Amazonia during the 2010 drought.
Global Biogeochemical Cycles,
29(10), 1739-1753.
Abstract:
Disentangling the contribution of multiple land covers to fire-mediated carbon emissions in Amazonia during the 2010 drought
In less than 15 years, the Amazon region experienced three major droughts. Links between droughts and fires have been demonstrated for the 1997/1998, 2005, and 2010 droughts. In 2010, emissions of 510 ± 120 Tg C were associated to fire alone in Amazonia. Existing approaches have, however, not yet disentangled the proportional contribution of multiple land cover sources to this total. We develop a novel integration of multisensor and multitemporal satellite-derived data on land cover, active fires, and burned area and an empirical model of fire-induced biomass loss to quantify the extent of burned areas and resulting biomass loss for multiple land covers in Mato Grosso (MT) state, southern Amazonia - the 2010 drought most impacted region. We show that 10.77% (96,855 km2) of MT burned. We estimated a gross carbon emission of 56.21 ± 22.5 Tg C from direct combustion of biomass, with an additional 29.4 ± 10 Tg C committed to be emitted in the following years due to dead wood decay. It is estimated that old-growth forest fires in the whole Brazilian Legal Amazon (BLA) have contributed to 14.81 Tg of C (11.75 Tg C to 17.87 Tg C) emissions to the atmosphere during the 2010 fire season, with an affected area of 27,555 km2. Total C loss from the 2010 fires in MT state and old-growth forest fires in the BLA represent, respectively, 77% (47% to 107%) and 86% (68.2% to 103%) of Brazil's National Plan on Climate Change annual target for Amazonia C emission reductions from deforestation.
Abstract.
Maeda EE, Kim H, Aragão LEOC, Famiglietti JS, Oki T (2015). Disruption of hydroecological equilibrium in southwest Amazon mediated by drought.
Geophysical Research LettersAbstract:
Disruption of hydroecological equilibrium in southwest Amazon mediated by drought
The impacts of droughts on the Amazon ecosystem have been broadly discussed in recent years, but a comprehensive understanding of the consequences is still missing. In this study, we show evidence of a fragile hydrological equilibrium in the western Amazon. While drainage systems located near the equator and the western Amazon do not show water deficit in years with average climate conditions, this equilibrium can be broken during drought events. More importantly, we show that this effect is persistent, taking years until the normal hydrological patterns are reestablished. We show clear links between persistent changes in forest canopy structure and changes in hydrological patterns, revealing physical evidence of hydrological mechanisms that may lead to permanent changes in parts of the Amazon ecosystem. If prospects of increasing drought frequency are confirmed, a change in the current hydroecological patterns in the western Amazon could take place in less than a decade.
Abstract.
Maeda EE, Kim H, Aragão LEOC, Famiglietti JS, Oki T (2015). Disruption of hydroecological equilibrium in southwest Amazon mediated by drought.
Geophysical Research Letters,
42(18), 7546-7553.
Abstract:
Disruption of hydroecological equilibrium in southwest Amazon mediated by drought
The impacts of droughts on the Amazon ecosystem have been broadly discussed in recent years, but a comprehensive understanding of the consequences is still missing. In this study, we show evidence of a fragile hydrological equilibrium in the western Amazon. While drainage systems located near the equator and the western Amazon do not show water deficit in years with average climate conditions, this equilibrium can be broken during drought events. More importantly, we show that this effect is persistent, taking years until the normal hydrological patterns are reestablished. We show clear links between persistent changes in forest canopy structure and changes in hydrological patterns, revealing physical evidence of hydrological mechanisms that may lead to permanent changes in parts of the Amazon ecosystem. If prospects of increasing drought frequency are confirmed, a change in the current hydroecological patterns in the western Amazon could take place in less than a decade.
Abstract.
Fauset S, Johnson MO, Gloor M, Baker TR, Monteagudo M A, Brienen RJW, Feldpausch TR, Lopez-Gonzalez G, Malhi Y, ter Steege H, et al (2015). Hyperdominance in Amazonian forest carbon cycling.
Nat Commun,
6Abstract:
Hyperdominance in Amazonian forest carbon cycling.
While Amazonian forests are extraordinarily diverse, the abundance of trees is skewed strongly towards relatively few 'hyperdominant' species. In addition to their diversity, Amazonian trees are a key component of the global carbon cycle, assimilating and storing more carbon than any other ecosystem on Earth. Here we ask, using a unique data set of 530 forest plots, if the functions of storing and producing woody carbon are concentrated in a small number of tree species, whether the most abundant species also dominate carbon cycling, and whether dominant species are characterized by specific functional traits. We find that dominance of forest function is even more concentrated in a few species than is dominance of tree abundance, with only ≈1% of Amazon tree species responsible for 50% of carbon storage and productivity. Although those species that contribute most to biomass and productivity are often abundant, species maximum size is also influential, while the identity and ranking of dominant species varies by function and by region.
Abstract.
Author URL.
Brienen RJW, Phillips OL, Feldpausch TR, Gloor E, Baker TR, Lloyd J, Lopez-Gonzalez G, Monteagudo-Mendoza A, Malhi Y, Lewis SL, et al (2015). Long-term decline of the Amazon carbon sink.
Nature,
519(7543), 344-348.
Abstract:
Long-term decline of the Amazon carbon sink.
Atmospheric carbon dioxide records indicate that the land surface has acted as a strong global carbon sink over recent decades, with a substantial fraction of this sink probably located in the tropics, particularly in the Amazon. Nevertheless, it is unclear how the terrestrial carbon sink will evolve as climate and atmospheric composition continue to change. Here we analyse the historical evolution of the biomass dynamics of the Amazon rainforest over three decades using a distributed network of 321 plots. While this analysis confirms that Amazon forests have acted as a long-term net biomass sink, we find a long-term decreasing trend of carbon accumulation. Rates of net increase in above-ground biomass declined by one-third during the past decade compared to the 1990s. This is a consequence of growth rate increases levelling off recently, while biomass mortality persistently increased throughout, leading to a shortening of carbon residence times. Potential drivers for the mortality increase include greater climate variability, and feedbacks of faster growth on mortality, resulting in shortened tree longevity. The observed decline of the Amazon sink diverges markedly from the recent increase in terrestrial carbon uptake at the global scale, and is contrary to expectations based on models.
Abstract.
Author URL.
Martini DZ, Moreira MA, Cruz de Aragão LEOE, Formaggio AR, Dalla-Nora EL (2015). Potential land availability for agricultural expansion in the Brazilian Amazon.
Land Use Policy,
49, 35-42.
Abstract:
Potential land availability for agricultural expansion in the Brazilian Amazon
The Amazon hosts one of the largest stocks of arable land in the world. However, little is known about the available extent of agricultural land in conformity with legal, agronomical and environmental requirements. This study aims to identify and quantify potentially available areas for agricultural expansion in the Brazilian Amazon considering the extent of: (i) legally available forested lands, (ii) previously converted lands with suitable productive capacity and (iii) previously converted lands free of land use conflicts. This analysis was carried out by integrating georeferenced information on land use, soil fertility, terrain slope, biomass, protected areas and land use policies (e.g. Brazilian Forest Code) into a conditional decision support procedure, based on Boolean inference techniques. Our results showed that 11.69% (493,103.03km2) of the Brazilian Amazon would be potentially available for agricultural expansion in the year 2010. This area was essentially dominated by forests (59.37%), followed by previously converted lands (40.63%). The extent of this area was equivalent to 75.86% of the total cultivated area in Brazil in 2010. However, the effective usage of these areas would have direct political and environmental implications. First, it is expected that the effective usage of available forests would detract recent achievements of the Brazilian Action Plan for Prevention and Control of Deforestation in the Amazon, which has reduced deforestation by 79% from historical rates. Moreover, the conversion of these areas could result in a committed emission of 13 ±1 Pg CO2eq to the atmosphere which is equivalent to the total emissions from land cover change registered in Brazil during the 2000-2010 period. Therefore, the compensation of environmental liabilities stands as the most consistent destination for the available forests mapped in this study. To minimize environmental impacts, agricultural expansion in the Brazilian Amazon should be restricted to already converted areas. This land cover class totalizes 200,000km2, which could support agricultural expansion without promoting the advance of deforestation.
Abstract.
Malhi Y, Doughty CE, Goldsmith GR, Metcalfe DB, Girardin CAJ, Marthews TR, del Aguila-Pasquel J, Aragão LEOC, Araujo-Murakami A, Brando P, et al (2015). The linkages between photosynthesis, productivity, growth and biomass in lowland Amazonian forests.
Global Change Biology,
21(6), 2283-2295.
Abstract:
The linkages between photosynthesis, productivity, growth and biomass in lowland Amazonian forests
Understanding the relationship between photosynthesis, net primary productivity and growth in forest ecosystems is key to understanding how these ecosystems will respond to global anthropogenic change, yet the linkages among these components are rarely explored in detail. We provide the first comprehensive description of the productivity, respiration and carbon allocation of contrasting lowland Amazonian forests spanning gradients in seasonal water deficit and soil fertility. Using the largest data set assembled to date, ten sites in three countries all studied with a standardized methodology, we find that (i) gross primary productivity (GPP) has a simple relationship with seasonal water deficit, but that (ii) site-to-site variations in GPP have little power in explaining site-to-site spatial variations in net primary productivity (NPP) or growth because of concomitant changes in carbon use efficiency (CUE), and conversely, the woody growth rate of a tropical forest is a very poor proxy for its productivity. Moreover, (iii) spatial patterns of biomass are much more driven by patterns of residence times (i.e. tree mortality rates) than by spatial variation in productivity or tree growth. Current theory and models of tropical forest carbon cycling under projected scenarios of global atmospheric change can benefit from advancing beyond a focus on GPP. By improving our understanding of poorly understood processes such as CUE, NPP allocation and biomass turnover times, we can provide more complete and mechanistic approaches to linking climate and tropical forest carbon cycling.
Abstract.
Malhi Y, Doughty CE, Goldsmith GR, Metcalfe DB, Girardin CAJ, Marthews TR, Del Aguila-Pasquel J, Aragão LEOC, Araujo-Murakami A, Brando P, et al (2015). The linkages between photosynthesis, productivity, growth and biomass in lowland Amazonian forests.
Glob Chang Biol,
21(6), 2283-2295.
Abstract:
The linkages between photosynthesis, productivity, growth and biomass in lowland Amazonian forests.
Understanding the relationship between photosynthesis, net primary productivity and growth in forest ecosystems is key to understanding how these ecosystems will respond to global anthropogenic change, yet the linkages among these components are rarely explored in detail. We provide the first comprehensive description of the productivity, respiration and carbon allocation of contrasting lowland Amazonian forests spanning gradients in seasonal water deficit and soil fertility. Using the largest data set assembled to date, ten sites in three countries all studied with a standardized methodology, we find that (i) gross primary productivity (GPP) has a simple relationship with seasonal water deficit, but that (ii) site-to-site variations in GPP have little power in explaining site-to-site spatial variations in net primary productivity (NPP) or growth because of concomitant changes in carbon use efficiency (CUE), and conversely, the woody growth rate of a tropical forest is a very poor proxy for its productivity. Moreover, (iii) spatial patterns of biomass are much more driven by patterns of residence times (i.e. tree mortality rates) than by spatial variation in productivity or tree growth. Current theory and models of tropical forest carbon cycling under projected scenarios of global atmospheric change can benefit from advancing beyond a focus on GPP. By improving our understanding of poorly understood processes such as CUE, NPP allocation and biomass turnover times, we can provide more complete and mechanistic approaches to linking climate and tropical forest carbon cycling.
Abstract.
Author URL.
Stark SC, Breshears DD, Garcia ES, Law DJ, Minor DM, Saleska SR, Swann ALS, Villegas JC, Aragão LEOC, Bella EM, et al (2015). Toward accounting for ecoclimate teleconnections: intra- and inter-continental consequences of altered energy balance after vegetation change.
Landscape EcologyAbstract:
Toward accounting for ecoclimate teleconnections: intra- and inter-continental consequences of altered energy balance after vegetation change
Context: Vegetation is projected to continue to undergo major structural changes in coming decades due to land conversion and climate change, including widespread forest die-offs. These vegetation changes are important not only for their local or regional climatic effects, but also because they can affect climate and subsequently vegetation in other regions or continents through “ecoclimate teleconnections”. Objectives: We propose that ecoclimate teleconnections are a fundamental link among regions within and across continents, and are central to advancing large-scale macrosystems ecology. Methods and results: We illustrate potential ecoclimate teleconnections in a bounding simulation that assumes complete tree cover loss in western North America due to tree die-off, and which predicts subsequent drying and reduced net primary productivity in other areas of North America, the Amazon and elsewhere. Central to accurately modeling such ecoclimate teleconnections is characterizing how vegetation change alters albedo and other components of the land-surface energy balance and then scales up to impact the climate system. We introduce a framework for rapid field-based characterization of vegetation structure and energy balance to help address this challenge. Conclusions: Ecoclimate teleconnections are likely a fundamental aspect of macrosystems ecology needed to account for alterations to large-scale atmospheric-ecological couplings in response to vegetation change, including deforestation, afforestation and die-off.
Abstract.
2014
Berenguer E, Ferreira J, Gardner TA, Aragão LEOC, De Camargo PB, Cerri CE, Durigan M, De Oliveira RC, Vieira ICG, Barlow J, et al (2014). A large-scale field assessment of carbon stocks in human-modified tropical forests.
Global Change Biology,
20(12), 3713-3726.
Abstract:
A large-scale field assessment of carbon stocks in human-modified tropical forests
Tropical rainforests store enormous amounts of carbon, the protection of which represents a vital component of efforts to mitigate global climate change. Currently, tropical forest conservation, science, policies, and climate mitigation actions focus predominantly on reducing carbon emissions from deforestation alone. However, every year vast areas of the humid tropics are disturbed by selective logging, understory fires, and habitat fragmentation. There is an urgent need to understand the effect of such disturbances on carbon stocks, and how stocks in disturbed forests compare to those found in undisturbed primary forests as well as in regenerating secondary forests. Here, we present the results of the largest field study to date on the impacts of human disturbances on above and belowground carbon stocks in tropical forests. Live vegetation, the largest carbon pool, was extremely sensitive to disturbance: forests that experienced both selective logging and understory fires stored, on average, 40% less aboveground carbon than undisturbed forests and were structurally similar to secondary forests. Edge effects also played an important role in explaining variability in aboveground carbon stocks of disturbed forests. Results indicate a potential rapid recovery of the dead wood and litter carbon pools, while soil stocks (0-30 cm) appeared to be resistant to the effects of logging and fire. Carbon loss and subsequent emissions due to human disturbances remain largely unaccounted for in greenhouse gas inventories, but by comparing our estimates of depleted carbon stocks in disturbed forests with Brazilian government assessments of the total forest area annually disturbed in the Amazon, we show that these emissions could represent up to 40% of the carbon loss from deforestation in the region. We conclude that conservation programs aiming to ensure the long-term permanence of forest carbon stocks, such as REDD+, will remain limited in their success unless they effectively avoid degradation as well as deforestation.
Abstract.
Berenguer E, Ferreira J, Gardner TA, Aragão LEOC, De Camargo PB, Cerri CE, Durigan M, Cosme De Oliveira Junior R, Vieira ICG, Barlow J, et al (2014). A large-scale field assessment of carbon stocks in human-modified tropical forests.
Glob Chang Biol,
20(12), 3713-3726.
Abstract:
A large-scale field assessment of carbon stocks in human-modified tropical forests.
Tropical rainforests store enormous amounts of carbon, the protection of which represents a vital component of efforts to mitigate global climate change. Currently, tropical forest conservation, science, policies, and climate mitigation actions focus predominantly on reducing carbon emissions from deforestation alone. However, every year vast areas of the humid tropics are disturbed by selective logging, understory fires, and habitat fragmentation. There is an urgent need to understand the effect of such disturbances on carbon stocks, and how stocks in disturbed forests compare to those found in undisturbed primary forests as well as in regenerating secondary forests. Here, we present the results of the largest field study to date on the impacts of human disturbances on above and belowground carbon stocks in tropical forests. Live vegetation, the largest carbon pool, was extremely sensitive to disturbance: forests that experienced both selective logging and understory fires stored, on average, 40% less aboveground carbon than undisturbed forests and were structurally similar to secondary forests. Edge effects also played an important role in explaining variability in aboveground carbon stocks of disturbed forests. Results indicate a potential rapid recovery of the dead wood and litter carbon pools, while soil stocks (0-30 cm) appeared to be resistant to the effects of logging and fire. Carbon loss and subsequent emissions due to human disturbances remain largely unaccounted for in greenhouse gas inventories, but by comparing our estimates of depleted carbon stocks in disturbed forests with Brazilian government assessments of the total forest area annually disturbed in the Amazon, we show that these emissions could represent up to 40% of the carbon loss from deforestation in the region. We conclude that conservation programs aiming to ensure the long-term permanence of forest carbon stocks, such as REDD+, will remain limited in their success unless they effectively avoid degradation as well as deforestation.
Abstract.
Author URL.
Gurdak DJ, Aragão LEOC, Rozas-Dávila A, Huasco WH, Cabrera KG, Doughty CE, Farfan-Rios W, Silva-Espejo JE, Metcalfe DB, Silman MR, et al (2014). Assessing above-ground woody debris dynamics along a gradient of elevation in Amazonian cloud forests in Peru: Balancing above-ground inputs and respiration outputs.
Plant Ecology and Diversity,
7(1-2), 143-160.
Abstract:
Assessing above-ground woody debris dynamics along a gradient of elevation in Amazonian cloud forests in Peru: Balancing above-ground inputs and respiration outputs
Background: Dead biomass, including woody debris (WD), is an important component of the carbon cycle in tropical forests. Aims: This study analyses WD (>2 cm) and other above-ground fluxes in mature tropical forest plots along an elevational gradient (210-3025 m above sea level) in southern Peru. Methods: This work was based on inventories of fine and coarse WD (FWD and CWD, respectively), above-ground biomass, and field-based and experimental respiration measurements. Results: Total WD stocks ranged from 6.26 Mg C ha-1 at 3025 m to 11.48 Mg C ha-1 at 2720 m. WD respiration was significantly correlated with moisture content (P < 0.001; R 2 = 0.25), temperature (P < 0.001; R 2 = 0.12) and wood density (P < 0.001; R 2 = 0.16). Controlled experiments showed that both water content and temperature increased respiration rates of individual WD samples. The full breadth of the temperature sensitivity coefficient, or Q 10, estimates, ranging from 1.14-2.13, was low compared to other studies. In addition, temperature sensitivity of WD respiration was greater for higher elevations. Conclusions: Carbon stocks, mortality and turnover of above-ground biomass varied widely and were not significantly related with elevation or slope. This study demonstrates that some forests may be a carbon source due to legacies of disturbance and increasing temperatures, which may cause additional, short-term carbon efflux from WD. Predictions of tropical forest carbon cycles under future climate should incorporate WD dynamics and related feedback.s © 2014 Copyright 2013 Botanical Society of Scotland and Taylor & Francis.
Abstract.
Ferreira J, Aragão LEOC, Barlow J, Barreto P, Berenguer E, Bustamante M, Gardner TA, Lees AC, Lima A, Louzada J, et al (2014). Brazil's environmental leadership at risk: Mining and dams threaten protected areas. Science, 346(6210), 706-707.
Maeda EE, Heiskanen J, Aragão LEOC, Rinne J (2014). Can MODIS EVI monitor ecosystem productivity in the Amazon rainforest?.
Geophysical Research Letters,
41(20), 7176-7183.
Abstract:
Can MODIS EVI monitor ecosystem productivity in the Amazon rainforest?
The enhanced vegetation index (EVI) obtained from satellite imagery has often been used as a proxy of vegetation functioning and productivity in the Amazon rainforest. However, recent studies indicate that EVI patterns are strongly affected by satellite data artifacts. Hence, it is unclear if EVI is sensitive to subtle seasonal variations in evergreen Amazon forest productivity. This study analyzes 12-years of Moderate Resolution Imaging Spectroradiometer (MODIS) EVI in order to evaluate its response to factors driving productivity in the Amazon. We show that, after removing cloud and aerosol contamination, and correcting bidirectional reflectance distribution function effects, radiation and rainfall extremes show no influence on EVI anomalies. However, EVI seasonal patterns are still evident after accounting for Sun-sensor geometry effects. This remaining pattern cannot be explained by solar radiation or rainfall, but it is significantly correlated to gross primary production (GPP). Nevertheless, we argue that the causality between GPP and EVI should be interpreted with caution. Key Points Monthly EVI anomalies are not sensitive to radiation or rainfall extremesEVI seasonality in the Amazon is still present after BRDF correctionAlthough EVI and GPP correlate, interpretations of causality require caution
Abstract.
Smith LT, Aragão LEOC, Sabel CE, Nakaya T (2014). Drought impacts on children's respiratory health in the Brazilian Amazon.
Sci Rep,
4Abstract:
Drought impacts on children's respiratory health in the Brazilian Amazon.
Drought conditions in Amazonia are associated with increased fire incidence, enhancing aerosol emissions with degradation in air quality. Quantifying the synergic influence of climate and human-driven environmental changes on human health is, therefore, critical for identifying climate change adaptation pathways for this vulnerable region. Here we show a significant increase (1.2%-267%) in hospitalisations for respiratory diseases in children under-five in municipalities highly exposed to drought. Aerosol was the primary driver of hospitalisations in drought affected municipalities during 2005, while human development conditions mitigated the impacts in 2010. Our results demonstrated that drought events deteriorated children's respiratory health particularly during 2005 when the drought was more geographically concentrated. This indicates that if governments act on curbing fire usage and effectively plan public health provision, as a climate change adaptation procedure, health quality would improve and public expenditure for treatment would decrease in the region during future drought events.
Abstract.
Author URL.
Ferreira J, Aragão LEOC, Barlow J, Barreto P, Berenguer E, Bustamante M, Gardner TA, Lees AC, Lima A, Louzada J, et al (2014). Environment and Development. Brazil's environmental leadership at risk.
Science,
346(6210), 706-707.
Author URL.
Aragão LEOC, Poulter B, Barlow JB, Anderson LO, Malhi Y, Saatchi S, Phillips OL, Gloor E (2014). Environmental change and the carbon balance of Amazonian forests.
Biological Reviews,
89(4), 913-931.
Abstract:
Environmental change and the carbon balance of Amazonian forests
Extreme climatic events and land-use change are known to influence strongly the current carbon cycle of Amazonia, and have the potential to cause significant global climate impacts. This review intends to evaluate the effects of both climate and anthropogenic perturbations on the carbon balance of the Brazilian Amazon and to understand how they interact with each other. By analysing the outputs of the Intergovernmental Panel for Climate Change (IPCC) Assessment Report 4 (AR4) model ensemble, we demonstrate that Amazonian temperatures and water stress are both likely to increase over the 21st Century. Curbing deforestation in the Brazilian Amazon by 62% in 2010 relative to the 1990s mean decreased the Brazilian Amazon's deforestation contribution to global land use carbon emissions from 17% in the 1990s and early 2000s to 9% by 2010. Carbon sources in Amazonia are likely to be dominated by climatic impacts allied with forest fires (48.3% relative contribution) during extreme droughts. The current net carbon sink (net biome productivity, NBP) of +0.16 (ranging from +0.11 to +0.21) Pg C year-1 in the Brazilian Amazon, equivalent to 13.3% of global carbon emissions from land-use change for 2008, can be negated or reversed during drought years [NBP = -0.06 (-0.31 to +0.01) Pg C year-1]. Therefore, reducing forest fires, in addition to reducing deforestation, would be an important measure for minimizing future emissions. Conversely, doubling the current area of secondary forests and avoiding additional removal of primary forests would help the Amazonian gross forest sink to offset approximately 42% of global land-use change emissions. We conclude that a few strategic environmental policy measures are likely to strengthen the Amazonian net carbon sink with global implications. Moreover, these actions could increase the resilience of the net carbon sink to future increases in drought frequency.
Abstract.
Aragão LEOC, Poulter B, Barlow JB, Anderson LO, Malhi Y, Saatchi S, Phillips OL, Gloor E (2014). Environmental change and the carbon balance of Amazonian forests. Biological Reviews
Fletcher IN, Aragão LEOC, Lima A, Shimabukuro Y, Friedlingstein P (2014). Fractal properties of forest fires in Amazonia as a basis for modelling pan-tropical burnt area.
Biogeosciences,
11(6), 1449-1459.
Abstract:
Fractal properties of forest fires in Amazonia as a basis for modelling pan-tropical burnt area
Current methods for modelling burnt area in dynamic global vegetation models (DGVMs) involve complex fire spread calculations, which rely on many inputs, including fuel characteristics, wind speed and countless parameters. They are therefore susceptible to large uncertainties through error propagation, but undeniably useful for modelling specific, small-scale burns. Using observed fractal distributions of fire scars in Brazilian Amazonia in 2005, we propose an alternative burnt area model for tropical forests, with fire counts as sole input and few parameters. This model is intended for predicting large-scale burnt area rather than looking at individual fire events. A simple parameterization of a tapered fractal distribution is calibrated at multiple spatial resolutions using a satellite-derived burnt area map. The model is capable of accurately reproducing the total area burnt (16 387 km2) and its spatial distribution. When tested pan-tropically using the MODIS MCD14ML active fire product, the model accurately predicts temporal and spatial fire trends, but the magnitude of the differences between these estimates and the GFED3.1 burnt area products varies per continent. © Author(s) 2014.
Abstract.
Mitchard ETA, Feldpausch TR, Brienen RJW, Lopez-Gonzalez G, Monteagudo A, Baker TR, Lewis SL, Lloyd J, Quesada CA, Gloor M, et al (2014). Markedly divergent estimates of amazon forest carbon density from ground plots and satellites. Global Ecology and Biogeography
Girardin CAJ, Espejob JES, Doughty CE, Huasco WH, Metcalfe DB, Durand-Baca L, Marthews TR, Aragao LEOC, Farfán-Rios W, García-Cabrera K, et al (2014). Productivity and carbon allocation in a tropical montane cloud forest in the Peruvian Andes.
Plant Ecology and Diversity,
7(1-2), 107-123.
Abstract:
Productivity and carbon allocation in a tropical montane cloud forest in the Peruvian Andes
Background: the slopes of the eastern Andes harbour some of the highest biodiversity on Earth and a high proportion of endemic species. However, there have been only a few and limited descriptions of carbon budgets in tropical montane forest regions. Aims: We present the first comprehensive data on the production, allocation and cycling of carbon for two high elevation (ca. 3000 m) tropical montane cloud forest plots in the Kosñipata Valley, Peruvian Andes. Methods: We measured the main components and seasonal variation of net primary productivity (NPP), autotrophic (R a) and heterotrophic (R h) respiration to estimate gross primary productivity (GPP) and carbon use efficiency (CUE) in two 1-ha plots. Results: NPP for the two plots was estimated to be 7.05 ± 0.39 and 8.04 ± 0.47 Mg C ha-1 year-1, GPP to be 22.33 ± 2.23 and 26.82 ± 2.97 Mg C ha-1 year-1 and CUE was 0.32 ± 0.04 and 0.30 ± 0.04. Conclusions: We found strong seasonality in NPP and moderate seasonality of R a, suggesting that forest NPP is driven by changes in photosynthesis and highlighting the importance of variation in solar radiation. Our findings imply that trees invest more in biomass production in the cooler season with lower solar radiation and more in maintenance during the warmer and high solar radiation period. © 2014 Copyright 2013 Botanical Society of Scotland and Taylor & Francis.
Abstract.
Huasco WH, Girardin CAJ, Doughty CE, Metcalfe DB, Baca LD, Silva-Espejo JE, Cabrera DG, Aragão LEOC, Davila AR, Marthews TR, et al (2014). Seasonal production, allocation and cycling of carbon in two mid-elevation tropical montane forest plots in the Peruvian Andes.
Plant Ecology and Diversity,
7(1-2), 125-142.
Abstract:
Seasonal production, allocation and cycling of carbon in two mid-elevation tropical montane forest plots in the Peruvian Andes
Background: Tropical montane cloud forests (TMCF) are unique ecosystems with high biodiversity and large carbon reservoirs. To date there have been limited descriptions of the carbon cycle of TMCF. Aims: We present results on the production, allocation and cycling of carbon for two mid-elevation (1500-1750 m) tropical montane cloud forest plots in San Pedro, Kosñipata Valley, Peru. Methods: We repeatedly recorded the components of net primary productivity (NPP) using biometric measurements, and autotrophic (R a) and heterotrophic (R h) respiration, using gas exchange measurements. From these we estimated gross primary productivity (GPP) and carbon use efficiency (CUE) at the plot level. Results: the plot at 1500 m was found very productive, with our results comparable with the most productive lowland Amazonian forests. The plot at 1750 m had significantly lower productivity, possibly because of greater cloud immersion. Both plots had similar patterns of NPP allocation, a substantial seasonality in NPP components and little seasonality in Ra. Conclusions: These two plots lie within the ecotone between lower and upper montane forests, near the level of the cloud base. Climate change is likely to increase elevation of the cloud base, resulting in shifts in forest functioning. Longer-term surveillance of the carbon cycle at these sites would yield valuable insights into the response of TMCFs to a shifting cloud base. © 2014 Copyright 2013 Botanical Society of Scotland and Taylor & Francis.
Abstract.
Girardin CAJ, Malhi Y, Feeley KJ, Rapp JM, Silman MR, Meir P, Huaraca Huasco W, Salinas N, Mamani M, Silva-Espejo JE, et al (2014). Seasonality of above-ground net primary productivity along an Andean altitudinal transect in Peru.
Journal of Tropical Ecology,
30(6), 503-519.
Abstract:
Seasonality of above-ground net primary productivity along an Andean altitudinal transect in Peru
Solar irradiance and precipitation are the most likely drivers of the seasonal variation of net primary productivity (NPP) in tropical forests. Since their roles remain poorly understood, we use litter traps, dendrometer bands and census data collected from one hectare permanent plots to quantify the seasonality of above-ground NPP components and weather parameters in 13 sites distributed along a 2800-m altitudinal gradient ranging from lowland Amazonia to the high Andes. We combine canopy leaf area index and litterfall data to describe the seasonality of canopy production. We hypothesize that solar irradiance is the primary driver of canopy phenology in wetter sites, whereas precipitation drives phenology in drier systems. The seasonal rhythm of canopy NPP components is in synchrony with solar irradiance at all altitudes. Leaf litterfall peaks in the late dry season, both in lowland (averaging 0.54 ± 0.08 Mg C ha y-1, n = 5) and montane forests (averaging 0.29 ± 0.04 Mg C ha y-1, n = 8). Peaks in above-ground coarse woody NPP appears to be triggered by the onset of rainfall in seasonal lowland rain forests (averaging 0.26 ± 0.04 Mg C ha y-1, n = 5, in November), but not in montane cloud forests.
Abstract.
Girardin CAJ, Malhi Y, Feeley KJ, Rapp JM, Silman MR, Meir P, Huaraca Huasco W, Salinas N, Mamani M, Silva-Espejo JE, et al (2014). Seasonality of above-ground net primary productivity along an Andean altitudinal transect in Peru.
Journal of Tropical EcologyAbstract:
Seasonality of above-ground net primary productivity along an Andean altitudinal transect in Peru
Abstract: Solar irradiance and precipitation are the most likely drivers of the seasonal variation of net primary productivity (NPP) in tropical forests. Since their roles remain poorly understood, we use litter traps, dendrometer bands and census data collected from one hectare permanent plots to quantify the seasonality of above-ground NPP components and weather parameters in 13 sites distributed along a 2800-m altitudinal gradient ranging from lowland Amazonia to the high Andes. We combine canopy leaf area index and litterfall data to describe the seasonality of canopy production. We hypothesize that solar irradiance is the primary driver of canopy phenology in wetter sites, whereas precipitation drives phenology in drier systems. The seasonal rhythm of canopy NPP components is in synchrony with solar irradiance at all altitudes. Leaf litterfall peaks in the late dry season, both in lowland (averaging 0.54 ± 0.08 Mg C ha y-1, n = 5) and montane forests (averaging 0.29 ± 0.04 Mg C ha y-1, n = 8). Peaks in above-ground coarse woody NPP appears to be triggered by the onset of rainfall in seasonal lowland rain forests (averaging 0.26 ± 0.04 Mg C ha y-1, n = 5, in November), but not in montane cloud forests. Copyright © Cambridge University Press 2014.
Abstract.
Galbraith D, Malhi Y, Aragão L, Baker T (2014). The ecosystem dynamics of Amazonian and Andean forests. Plant Ecology and Diversity, 7(1-2), 1-6.
Doughty CE, Metcalfe DB, da Costa MC, de Oliveira AAR, Neto GFC, Silva JA, Aragão LEOC, Almeida SS, Quesada CA, Girardin CAJ, et al (2014). The production, allocation and cycling of carbon in a forest on fertile terra preta soil in eastern Amazonia compared with a forest on adjacent infertile soil.
Plant Ecology and Diversity,
7(1-2), 41-53.
Abstract:
The production, allocation and cycling of carbon in a forest on fertile terra preta soil in eastern Amazonia compared with a forest on adjacent infertile soil
Background: Terra preta do indio or 'dark earth' soils formed as a result of a long-term addition of organic matter by indigenous peoples in Amazonia. Aims: Here we report on the first study of productivity, allocation and carbon cycling from a terra preta plot in eastern Amazonia (Caxiuanã, Pará, Brazil), and contrast its dynamics with a nearby plot on infertile soil (ferralsols). Methods: We determined total net primary production (NPP) for fine roots, wood, and canopy and total autotrophic respiration (rhizosphere, wood, and canopy respiration) from two 1-ha plots on contrasting soils. Results: Both gross primary productivity (GPP) (35.68 ± 3.65 vs. 32.08 ± 3.46 Mg C ha-1 year-1) and carbon use efficiency (CUE) (0.44 ± 0.06 vs. 0.42 ± 0.05) were slightly higher at the terra preta plot. Total NPP (15.77 ± 1.13 Mg C ha-1 year-1 vs. 13.57 ± 0.60 Mg C ha-1 year-1) and rates of fine root production (6.41 ± 1.08 vs. 3.68 ± 0.52 Mg C ha-1 year-1) were also greater at the terra preta plot vs. the tower plot. Conclusions: Forests on terra preta soil fix slightly more carbon and allocate slightly more of that carbon towards growth than forests on the infertile plot, which leads to greater total NPP, which was disproportionately allocated to fine roots. However, since increased fine root NPP was partially offset by increased heterotrophic soil respiration, the increased root growth was unlikely to greatly enhance soil carbon stocks in terra preta soils. © 2014 Copyright 2013 Botanical Society of Scotland and Taylor & Francis.
Abstract.
Malhi Y, Farfán Amézquita F, Doughty CE, Silva-Espejo JE, Girardin CAJ, Metcalfe DB, Aragão LEOC, Huaraca-Quispe LP, Alzamora-Taype I, Eguiluz-Mora L, et al (2014). The productivity, metabolism and carbon cycle of two lowland tropical forest plots in south-western Amazonia, Peru.
Plant Ecology and Diversity,
7(1-2), 85-105.
Abstract:
The productivity, metabolism and carbon cycle of two lowland tropical forest plots in south-western Amazonia, Peru
Background: the forests of western Amazonia are known to be more dynamic that the better-studied forests of eastern Amazonia, but there has been no comprehensive description of the carbon cycle of a western Amazonian forest. Aims: We present the carbon budget of two forest plots in Tambopata in south-eastern Peru, western Amazonia. In particular, we present, for the first time, the seasonal variation in the detailed carbon budget of a tropical forest. Methods: We measured the major components of net primary production (NPP) and total autotrophic respiration over 3-6 years. Results: the NPP for the two plots was 15.1 ± 0.8 and 14.2 ± 1.0 Mg C ha-1 year-1, the gross primary productivity (GPP) was 35.5 ± 3.6 and 34.5 ± 3.5 Mg C ha-1 year-1, and the carbon use efficiency (CUE) was 0.42 ± 0.05 and 0.41 ± 0.05. NPP and CUE showed a large degree of seasonality. Conclusions: the two plots were similar in carbon cycling characteristics despite the different soils, the most notable difference being high allocation of NPP to canopy and low allocation to fine roots in the Holocene floodplain plot. The timing of the minima in the wet-dry transition suggests they are driven by phenological rhythms rather than being driven directly by water stress. When compared with results from forests on infertile forests in humid lowland eastern Amazonia, the plots have slightly higher GPP, but similar patterns of CUE and carbon allocation. © 2014 Copyright 2013 Botanical Society of Scotland and Taylor & Francis.
Abstract.
2013
Gardner TA, Ferreira J, Barlow J, Lees AC, Parry L, Vieira ICÉG, Berenguer E, Abramovay R, Aleixo A, Andretti C, et al (2013). A social and ecological assessment of tropical land uses at multiple scales: the Sustainable Amazon Network.
Philosophical transactions of the Royal Society of London. Series B, Biological sciences,
368(1619).
Abstract:
A social and ecological assessment of tropical land uses at multiple scales: the Sustainable Amazon Network
Science has a critical role to play in guiding more sustainable development trajectories. Here, we present the Sustainable Amazon Network (Rede Amazônia Sustentável, RAS): a multidisciplinary research initiative involving more than 30 partner organizations working to assess both social and ecological dimensions of land-use sustainability in eastern Brazilian Amazonia. The research approach adopted by RAS offers three advantages for addressing land-use sustainability problems: (i) the collection of synchronized and co-located ecological and socioeconomic data across broad gradients of past and present human use; (ii) a nested sampling design to aid comparison of ecological and socioeconomic conditions associated with different land uses across local, landscape and regional scales; and (iii) a strong engagement with a wide variety of actors and non-research institutions. Here, we elaborate on these key features, and identify the ways in which RAS can help in highlighting those problems in most urgent need of attention, and in guiding improvements in land-use sustainability in Amazonia and elsewhere in the tropics. We also discuss some of the practical lessons, limitations and realities faced during the development of the RAS initiative so far.
Abstract.
Gardner TA, Ferreira J, Barlow J, Lees AC, Parry L, Guimaraes Vieira IC, Berenguer E, Abramovay R, Aleixo A, Andretti C, et al (2013). A social and ecological assessment of tropical land uses at multiple scales: the Sustainable Amazon Network (vol 368, 20120166, 2013).
PHILOSOPHICAL TRANSACTIONS OF THE ROYAL SOCIETY B-BIOLOGICAL SCIENCES,
368(1624).
Author URL.
Gardner TA, Ferreira J, Barlow J, Lees AC, Parry L, Vieira ICG, Berenguer E, Abramovay R, Aleixo A, Andretti C, et al (2013). A social and ecological assessment of tropical land uses at multiple scales: the Sustainable Amazon Network.
Philos Trans R Soc Lond B Biol Sci,
368(1619).
Abstract:
A social and ecological assessment of tropical land uses at multiple scales: the Sustainable Amazon Network.
Science has a critical role to play in guiding more sustainable development trajectories. Here, we present the Sustainable Amazon Network (Rede Amazônia Sustentável, RAS): a multidisciplinary research initiative involving more than 30 partner organizations working to assess both social and ecological dimensions of land-use sustainability in eastern Brazilian Amazonia. The research approach adopted by RAS offers three advantages for addressing land-use sustainability problems: (i) the collection of synchronized and co-located ecological and socioeconomic data across broad gradients of past and present human use; (ii) a nested sampling design to aid comparison of ecological and socioeconomic conditions associated with different land uses across local, landscape and regional scales; and (iii) a strong engagement with a wide variety of actors and non-research institutions. Here, we elaborate on these key features, and identify the ways in which RAS can help in highlighting those problems in most urgent need of attention, and in guiding improvements in land-use sustainability in Amazonia and elsewhere in the tropics. We also discuss some of the practical lessons, limitations and realities faced during the development of the RAS initiative so far.
Abstract.
Author URL.
Gurdak DJ, Aragão LEOC, Rozas-Dávila A, Huasco WH, Cabrera KG, Doughty CE, Farfan-Rios W, Silva-Espejo JE, Metcalfe DB, Silman MR, et al (2013). Assessing above-ground woody debris dynamics along a gradient of elevation in Amazonian cloud forests in Peru: balancing above-ground inputs and respiration outputs. Plant Ecology and Diversity
Ruhoff AL, Paz AR, Aragao LEOC, Mu Q, Malhi Y, Collischonn W, Rocha HR, Running SW (2013). Assessment of the MODIS global evapotranspiration algorithm using eddy covariance measurements and hydrological modelling in the Rio Grande basin. Hydrological Sciences Journal
Ruhoff AL, Paz AR, Aragao LEOC, Mu Q, Malhi Y, Collischonn W, Rocha HR, Running SW (2013). Assessment of the MODIS global evapotranspiration algorithm using eddy covariance measurements and hydrological modelling in the Rio Grande basin.
Hydrological Sciences Journal,
58(8), 1658-1676.
Abstract:
Assessment of the MODIS global evapotranspiration algorithm using eddy covariance measurements and hydrological modelling in the Rio Grande basin
Remote sensing is considered the most effective tool for estimating evapotranspiration (ET) over large spatial scales. Global terrestrial ET estimates over vegetated land surfaces are now operationally produced at 1-km spatial resolution using data from the Moderate Resolution Imaging Spectroradiometer (MODIS) and the MOD16 algorithm. To evaluate the accuracy of this product, ground-based measurements of energy fluxes obtained from eddy covariance sites installed in tropical biomes and from a hydrological model (MGB-IPH) were used to validate MOD16 products at local and regional scales. We examined the accuracy of the MOD16 algorithm at two sites in the Rio Grande basin, Brazil, one characterized by a sugar-cane plantation (USE), the other covered by natural savannah vegetation (PDG) for the year 2001. Inter-comparison between 8-day average MOD16 ET estimates and flux tower measurements yielded correlations of 0.78 to 0.81, with root mean square errors (RMSE) of 0.78 and 0.46 mm d-1, at PDG and USE, respectively. At the PDG site, the annual ET estimate derived by the MOD16 algorithm was 19% higher than the measured amount. For the average annual ET at the basin-wide scale (over an area of 145 000 km2), MOD16 estimates were 21% lower than those from the hydrological model MGB-IPH. Misclassification of land use and land cover was identified as the largest contributor to the error from the MOD16 algorithm. These estimates improve significantly when results are integrated into monthly or annual time intervals, suggesting that the algorithm has a potential for spatial and temporal monitoring of the ET process, continuously and systematically, through the use of remote sensing data. © 2013 IAHS Press.
Abstract.
da Costa ACL, Metcalfe DB, Doughty CE, de Oliveira AAR, Neto GFC, da Costa MC, Silva Junior JDA, Aragão LEOC, Almeida S, Galbraith DR, et al (2013). Ecosystem respiration and net primary productivity after 8-10 years of experimental through-fall reduction in an eastern Amazon forest. Plant Ecology and Diversity
Silva FB, Shimabukuro YE, Aragão LEOC, Anderson LO, Pereira G, Cardozo F, Arai E (2013). Erratum: Large-scale heterogeneity of Amazonian phenology revealed from 26-year long AVHRR/NDVI time-series (Environmental Research Letters (2013) 8 (024011)). Environmental Research Letters, 8(2).
Silva FB, Shimabukuro YE, Aragão LEOC, Anderson LO, Pereira G, Cardozo F, Arai E (2013). Erratum: Large-scale heterogeneity of Amazonian phenology revealed from 26-year long AVHRR/NDVI time-series (Environmental Research Letters (2013) 8 (024011)). Environmental Research Letters, 8(2).
Girardin CAJ, Aragao LEOC, Malhi Y, Huaraca Huasco W, Metcalfe DB, Durand L, Mamani M, Silva-Espejo JE, Whittaker RJ (2013). Fine root dynamics along an elevational gradient in tropical Amazonian and Andean forests.
GLOBAL BIOGEOCHEMICAL CYCLES,
27(1), 252-264.
Author URL.
Silva FB, Shimabukuro YE, Aragao LEOC, Anderson LO, Pereira G, Cardozo F, Arai E (2013). Large-scale heterogeneity of Amazonian phenology revealed from 26-year long AVHRR/NDVI time-series.
ENVIRONMENTAL RESEARCH LETTERS,
8(2).
Author URL.
Saatchi S, Asefi-Najafabady S, Malhi Y, Aragão LEOC, Anderson LO, Myneni RB, Nemani R (2013). Persistent effects of a severe drought on Amazonian forest canopy.
Proc Natl Acad Sci U S A,
110(2), 565-570.
Abstract:
Persistent effects of a severe drought on Amazonian forest canopy.
Recent Amazonian droughts have drawn attention to the vulnerability of tropical forests to climate perturbations. Satellite and in situ observations have shown an increase in fire occurrence during drought years and tree mortality following severe droughts, but to date there has been no assessment of long-term impacts of these droughts across landscapes in Amazonia. Here, we use satellite microwave observations of rainfall and canopy backscatter to show that more than 70 million hectares of forest in western Amazonia experienced a strong water deficit during the dry season of 2005 and a closely corresponding decline in canopy structure and moisture. Remarkably, and despite the gradual recovery in total rainfall in subsequent years, the decrease in canopy backscatter persisted until the next major drought, in 2010. The decline in backscatter is attributed to changes in structure and water content associated with the forest upper canopy. The persistence of low backscatter supports the slow recovery (>4 y) of forest canopy structure after the severe drought in 2005. The result suggests that the occurrence of droughts in Amazonia at 5-10 y frequency may lead to persistent alteration of the forest canopy.
Abstract.
Author URL.
Girardin CAJ, Espejob JES, Doughty CE, Huasco WH, Metcalfe DB, Durand-Baca L, Marthews TR, Aragao LEOC, Farfán-Rios W, García-Cabrera K, et al (2013). Productivity and carbon allocation in a tropical montane cloud forest in the Peruvian Andes. Plant Ecology and Diversity
Huasco WH, Girardin CAJ, Doughty CE, Metcalfe DB, Baca LD, Silva-Espejo JE, Cabrera DG, Aragão LEOC, Davila AR, Marthews TR, et al (2013). Seasonal production, allocation and cycling of carbon in two mid-elevation tropical montane forest plots in the Peruvian Andes. Plant Ecology and Diversity
Silva Júnior JDA, Da Costa ACL, De Azevedo PV, Da Costa RF, Metcalfe DB, Gonçalves PHL, Braga AP, Malhi YS, De Aragão LEOEC, Meir P, et al (2013). Soil CO<inf>2</inf> Efflux in Caxiuanã National Forest, Pará, during the ESECAFLOR/LBA experiment.
Revista Brasileira de Meteorologia,
28(1), 85-94.
Abstract:
Soil CO2 Efflux in Caxiuanã National Forest, Pará, during the ESECAFLOR/LBA experiment
The ESECAFLOR/LBA experiment was carried out at the Caxiuanã National Forest, Pará State, and this article intends to investigate the effect of hydrological stress on the total soil respiration. Two adjacent 1 hectare plots were defined in January 2002. One plot remained in its natural conditions and was used as a control (A), while in the exclusion plot (B) plastic cover panels were installed in order to drain about 70% of the total rainfall to outside of the plot. Accumulated monthly rainfall was recorded from 2005 January to December. During 2005 the rainfall over the ECFPn was 2,211.6 mm, or 9.96% above the mean of 2,011.2 mm. The average soil moisture was 15.6±9.2 and 9.5±3.4% in the plots a and B, respectively. The average soil temperature was 25.6±0.4 and 25.7±0.5 oC, for the a and B plots, respectively. The average soil CO2 flux was 3.46±0.44 and 3.21±0.84 μmolCO2 m-2s-1 in the a and B plots, respectively. With the exclusion of part of rain in plot B, it had a reduction of 7.23% in the soil CO2 flux (0.25 μmolCO2 m-2s-1), 39.1% in the soil humidity (6.1p.p.), and an increase of 0.39% in the soil temperature (0.1oC). The soil moisture in parcel B was lesser than in the parcel A, due to the exclusion system of rain. However at the beginning of the year, site B undergone some changes causing the measuring values to be about the same on both areas.
Abstract.
Malhi Y, Saatchi S, Girardin C, Aragão LEOC (2013). The Production, Storage, and Flow of Carbon in Amazonian Forests. In (Ed)
Amazonia and Global Change, 355-372.
Abstract:
The Production, Storage, and Flow of Carbon in Amazonian Forests
Abstract.
Doughty CE, Metcalfe DB, da Costa MC, de Oliveira AAR, Neto GFC, Silva JA, Aragão LEOC, Almeida SS, Quesada CA, Girardin CAJ, et al (2013). The production, allocation and cycling of carbon in a forest on fertile terra preta soil in eastern Amazonia compared with a forest on adjacent infertile soil. Plant Ecology and Diversity
Malhi Y, Farfán Amézquita F, Doughty CE, Silva-Espejo JE, Girardin CAJ, Metcalfe DB, Aragão LEOC, Huaraca-Quispe LP, Alzamora-Taype I, Eguiluz-Mora L, et al (2013). The productivity, metabolism and carbon cycle of two lowland tropical forest plots in south-western Amazonia, Peru. Plant Ecology and Diversity
Vinya R, Malhi Y, Fisher JB, Brown N, Brodribb TJ, Aragao LE (2013). Xylem cavitation vulnerability influences tree species' habitat preferences in miombo woodlands.
Oecologia,
173(3), 711-720.
Abstract:
Xylem cavitation vulnerability influences tree species' habitat preferences in miombo woodlands
Although precipitation plays a central role in structuring Africa's miombo woodlands, remarkably little is known about plant-water relations in this seasonally dry tropical forest. Therefore, in this study, we investigated xylem vulnerability to cavitation for nine principal tree species of miombo woodlands, which differ in habitat preference and leaf phenology. We measured cavitation vulnerability (Ψ50), stem-area specific hydraulic conductivity (K S), leaf specific conductivity (K L), seasonal variation in predawn water potential (ΨPD) and xylem anatomical properties [mean vessel diameter, mean hydraulic diameter, mean hydraulic diameter accounting for 95 % flow, and maximum vessel length (V L)]. Results show that tree species with a narrow habitat range (mesic specialists) were more vulnerable to cavitation than species with a wide habitat range (generalists). Ψ50 for mesic specialists ranged between -1.5 and -2.2 MPa and that for generalists between -2.5 and -3.6 MPa. While mesic specialists exhibited the lowest seasonal variation in ΨPD, generalists displayed significant seasonal variations in ΨPD suggesting that the two miombo habitat groups differ in their rooting depth. We observed a strong trade-off between K S and Ψ50 suggesting that tree hydraulic architecture is one of the decisive factors setting ecological boundaries for principal miombo species. While vessel diameters correlated weakly (P > 0.05) with Ψ50, V L was positively and significantly correlated with Ψ50. ΨPD was significantly correlated with Ψ50 further reinforcing the conclusion that tree hydraulic architecture plays a significant role in species' habitat preference in miombo woodlands. © 2013 Springer-Verlag Berlin Heidelberg.
Abstract.
Vinya R, Malhi Y, Fisher JB, Brown N, Brodribb TJ, Aragao LE (2013). Xylem cavitation vulnerability influences tree species' habitat preferences in miombo woodlands.
Oecologia,
173(3), 711-720.
Abstract:
Xylem cavitation vulnerability influences tree species' habitat preferences in miombo woodlands.
Although precipitation plays a central role in structuring Africa's miombo woodlands, remarkably little is known about plant-water relations in this seasonally dry tropical forest. Therefore, in this study, we investigated xylem vulnerability to cavitation for nine principal tree species of miombo woodlands, which differ in habitat preference and leaf phenology. We measured cavitation vulnerability (Ψ(50)), stem-area specific hydraulic conductivity (K S), leaf specific conductivity (K L), seasonal variation in predawn water potential (Ψ(PD)) and xylem anatomical properties [mean vessel diameter, mean hydraulic diameter, mean hydraulic diameter accounting for 95 % flow, and maximum vessel length (V L)]. Results show that tree species with a narrow habitat range (mesic specialists) were more vulnerable to cavitation than species with a wide habitat range (generalists). Ψ(50) for mesic specialists ranged between -1.5 and -2.2 MPa and that for generalists between -2.5 and -3.6 MPa. While mesic specialists exhibited the lowest seasonal variation in Ψ(PD), generalists displayed significant seasonal variations in Ψ(PD) suggesting that the two miombo habitat groups differ in their rooting depth. We observed a strong trade-off between K S and Ψ(50) suggesting that tree hydraulic architecture is one of the decisive factors setting ecological boundaries for principal miombo species. While vessel diameters correlated weakly (P > 0.05) with Ψ(50), V L was positively and significantly correlated with Ψ(50). Ψ(PD) was significantly correlated with Ψ(50) further reinforcing the conclusion that tree hydraulic architecture plays a significant role in species' habitat preference in miombo woodlands.
Abstract.
Author URL.
2012
Ruhoff AL, Paz AR, Collischonn W, Aragao LEOC, Rocha HR, Malhi YS (2012). A MODIS-Based Energy Balance to Estimate Evapotranspiration for Clear-Sky Days in Brazilian Tropical Savannas.
REMOTE SENSING,
4(3), 703-725.
Author URL.
Malhado ACM, Malhi Y, Whittaker RJ, Ladle RJ, ter Steege H, Fabré NN, Phillips O, Laurance WF, Aragão LEOC, Pitman NCA, et al (2012). Drip-tips are Associated with Intensity of Precipitation in the Amazon Rain Forest.
Biotropica,
44(6), 728-737.
Abstract:
Drip-tips are Associated with Intensity of Precipitation in the Amazon Rain Forest
Drip-tips are a common feature of the leaves of rain forest trees, but their functional significance remains contested. The most widely accepted hypothesis is that drip-tips assist drainage of the lamina thereby aiding drying of the leaf surface and reducing the rate of colonization and abundance of epiphyllic organisms. The drying action of drip-tips may also enhance transpiration and reduce the need for investment in support structures. Furthermore, drip-tips may help prevent splash erosion around the base of the tree. Data from 130 forest Amazonian plots are used to investigate the abundance and distribution of drip-tips and, through regression methods that incorporate spatial autocorrelation, seek to identify associations between the frequency of drip-tips and a range of climatic variables. The average frequency of species and trees with drip-tips across all plots was 32 and 33 percent, respectively. Trees and species with drip-tips were significantly more prevalent in the Central-East Amazon than the other regions. Drip-tips were also associated with tree species that have smaller maximum heights and with trees with smaller trunk diameters. The proportion of species and individuals with drip-tips was more strongly correlated with precipitation of the wettest trimester than with total annual precipitation or length of the dry season. Our results extend and provide support for both existing hypotheses for the functional benefit of possessing a drip-tip. Moreover, the currently unrecognized macrogeographic association between the frequency of drip-tips in trees of the tropical forest understory and areas of heavy precipitation suggests a new function for this trait. © 2012 by the Association for Tropical Biology and Conservation.
Abstract.
Malhado ACM, Malhi Y, Whittaker RJ, Ladle RJ, ter Steege H, Fabré NN, Phillips O, Laurance WF, Aragão LE, Pitman NC, et al (2012). Drip-tips are Associated with Intensity of Precipitation in the Amazon Rain Forest. Biotropica
Aragão LEOC (2012). Environmental science: the rainforest's water pump.
Nature,
489(7415), 217-218.
Author URL.
Lima A, Silva TSF, de Aragão LEOEC, de Feitas RM, Adami M, Formaggio AR, Shimabukuro YE (2012). Land use and land cover changes determine the spatial relationship between fire and deforestation in the Brazilian Amazon.
Applied Geography,
34, 239-246.
Abstract:
Land use and land cover changes determine the spatial relationship between fire and deforestation in the Brazilian Amazon
An increased frequency of droughts is predicted for the Amazon rainforest in the 21st century, which, combined with deforestation, could exacerbate fire occurrence in the region. There is ample evidence of the association between fire use and deforestation in the land use and land cover change (LULCC) processes occurring in the Amazon region, but there are no studies on the actual spatial structuring and spatial association between these events. The present study evaluates the existence of such relationships through the use of remotely sensed data and spatial analysis techniques for an active deforestation frontier covering portions of the states of Rondônia and Mato Grosso in the Brazilian Amazon. A map of burn scars for the year 2005 was produced using a Linear Spectral Mixture Model (LSMM) transformation of Landsat Thematic Mapper (TM) images, with subsequent unsupervised classification and manual editing. Annual and aggregated maps of deforested areas up to 2005, produced by the Brazilian Amazon Deforestation Estimation Project (PRODES), were also used. The amount of burn scar occurrences inside both recent (2002e2005) and old (prior to 2002) deforested areas was then determined, and the spatial structure of both variables was assessed using Mantel tests for multiple aggregation scales. A partial Mantel test was also used to test the spatial correlation between burn scars and deforested areas, accounting for the existence of spatial structure. The results show that there is a significant spatial association between recent deforestation and the occurrence of fires. In addition, we identified a large amount of burned areas (~55%) within older deforested areas. These results highlight the following: 1) the direct role of fire in the land use and land cover change processes in the Brazilian Amazon, and 2) that fire also widely affects previously degraded vegetation, with significant implications for current estimates of forest fire-associated atmospheric carbon emission in the Amazon region. © 2011 Elsevier Ltd.
Abstract.
Marthews TR, Malhi Y, Girardin CAJ, Silva Espejo JE, Aragão LEOC, Metcalfe DB, Rapp JM, Mercado LM, Fisher RA, Galbraith DR, et al (2012). Simulating forest productivity along a neotropical elevational transect: Temperature variation and carbon use efficiency. Global Change Biology
Marthews TR, Malhi Y, Girardin CAJ, Silva Espejo JE, Aragão LEOC, Metcalfe DB, Rapp JM, Mercado LM, Fisher RA, Galbraith DR, et al (2012). Simulating forest productivity along a neotropical elevational transect: Temperature variation and carbon use efficiency.
Global Change Biology,
18(9), 2882-2898.
Abstract:
Simulating forest productivity along a neotropical elevational transect: Temperature variation and carbon use efficiency
A better understanding of the mechanisms controlling the magnitude and sign of carbon components in tropical forest ecosystems is important for reliable estimation of this important regional component of the global carbon cycle. We used the JULES vegetation model to simulate all components of the carbon balance at six sites along an Andes-Amazon transect across Peru and Brazil and compared the results to published field measurements. In the upper montane zone the model predicted a lack of forest vegetation, indicating a need for better parameterization of the responses of cloud forest vegetation within the model. In the lower montane and lowland zones simulated ecosystem productivity and respiration were predicted with reasonable accuracy, although not always within the error bounds of the observations. Model-predicted carbon use efficiency in this transect surprisingly did not increase with elevation, but remained close to the 'temperate' value 0.5. Upper montane forests were predicted to allocate ~50% of carbon fixation to biomass maintenance and growth, despite available measurements showing that they only allocate ~33%. This may be explained by elevational changes in the balance between growth and maintenance respiration within the forest canopy, as controlled by both temperature- and pressure-mediated processes, which is not yet well represented in current vegetation models. © 2012 Blackwell Publishing Ltd.
Abstract.
Lima A, Moscardo A, Silva T, Leitold V, Coura S, Aragao LEOC, Rudorf BF, Formaggio AR, Shimabukuro YE (2012). Spatial - Temporal pattern of forest regeneration in areas deforested in the Eastern Amazon.
International Geoscience and Remote Sensing Symposium (IGARSS), 6283-6286.
Abstract:
Spatial - Temporal pattern of forest regeneration in areas deforested in the Eastern Amazon
The objective of this work was to identify and monitor forest regeneration for a period of eight years after deforestation events occurred in 2001 in the Eastern Amazon region. The study utilized Landsat Thematic Mapper (TM) images acquired for scene 224/65 (path/row), for the following dates: 07/06/2000 (Geocover product), 08/02/2001, 08/29/2002, 07/04/2005 (Geocover product) and 08/08/2009. Deforestation data was obtained from the PRODES deforestation mapping program for the year 2001. The results showed a large and increasing area of forest regeneration within the area and period of study. The first year after deforestation showed the highest proportion of regeneration (20%), which can be attributed to the known pattern of less intensive land use in the initial years after vegetation removal, associated with stem regeneration and germination from the remaining seed banks. The proportion of regenerated area decreased over the years (through new deforestation of regenerating areas), but still occupied 13% of the area deforested in 2001 at the end of the eight-year period (2001-2009). Another important result showed that from the total area regenerated by 2009, 60% started the recovery process immediately after the 2001 deforestation event, and had no evidence of economic use during the studied period (i.e. no justification exists for the observed deforestation in the first place). These results emphasize the importance of better understanding and quantifying the role of biophysical and socio-economic factors in the dynamics of forest regeneration in the Amazon, and could help improve carbon emission and biodiversity studies in the region. © 2012 IEEE.
Abstract.
Gloor M, Gatti L, Brienen R, Feldpausch TR, Phillips OL, Miller J, Ometto JP, Rocha H, Baker T, De Jong B, et al (2012). The carbon balance of South America: a review of the status, decadal trends and main determinants.
Biogeosciences,
9(12), 5407-5430.
Abstract:
The carbon balance of South America: a review of the status, decadal trends and main determinants
We summarise the contemporary carbon budget of South America and relate it to its dominant controls: population and economic growth, changes in land use practices and a changing atmospheric environment and climate. Component flux estimate methods we consider sufficiently reliable for this purpose encompass fossil fuel emission inventories, biometric analysis of old-growth rainforests, estimation of carbon release associated with deforestation based on remote sensing and inventories, and agricultural export data. Alternative methods for the estimation of the continental-scale net land to atmosphere CO2 flux, such as atmospheric transport inverse modelling and terrestrial biosphere model predictions, are, we find, hampered by the data paucity, and improved parameterisation and validation exercises are required before reliable estimates can be obtained. From our analysis of available data, we suggest that South America was a net source to the atmosphere during the 1980s (∼ 0.3-0.4 Pg C a−1) and close to neutral (∼ 0.1 Pg C a−1) in the 1990s. During the latter period, carbon uptake in old-growth forests nearly compensated for the carbon release associated with fossil fuel burning and deforestation. Annual mean precipitation over tropical South America as inferred from Amazon River discharge shows a long-term upward trend. Although, over the last decade dry seasons have tended to be drier, with the years 2005 and 2010 in particular experiencing strong droughts. On the other hand, precipitation during the wet seasons also shows an increasing trend. Air temperatures have also increased slightly. Also with increases in atmospheric CO2 concentrations, it is currently unclear what effect these climate changes are having on the forest carbon balance of the region. Current indications are that the forests of the Amazon Basin have acted as a substantial long-term carbon sink, but with the most recent measurements suggesting that this sink may be weakening. Economic development of the tropical regions of the continent is advancing steadily, with exports of agricultural products being an important driver and witnessing a strong upturn over the last decade. © Author(s) 2012.
Abstract.
Barlow J, Parry L, Gardner TA, Ferreira J, Aragão LEOC, Carmenta R, Berenguer E, Vieira ICG, Souza C, Cochrane MA, et al (2012). The critical importance of considering fire in REDD+ programs.
Biological Conservation,
154, 1-8.
Abstract:
The critical importance of considering fire in REDD+ programs
Fires are increasingly responsible for forest degradation in the humid tropics due to the expansion of fire-dependent agriculture, fragmentation, intensive logging practices and severe droughts. However, these forest fires have been largely overlooked by negotiations for Reducing Emissions from Deforestation and Degradation (REDD+). This paper examines how forest fires affect REDD+ schemes by compromising carbon permanence; undermining the potential of sustainable forest management and reforestation and regeneration activities in tropical countries; and threatening the additional benefits that can be accrued from REDD+, including biodiversity conservation and rural poverty alleviation. Narrowly focusing on avoiding deforestation, the sustainable management of forests or regeneration schemes will not always guarantee protection from fire occurrence, and investments in tropical forests may ultimately fail to achieve long-term emission reductions unless they also reduce the risk of forest fires. Integrating forest fire reduction into REDD+ presents many challenges, requiring: changes in agricultural practices that take place outside of the remaining forests; the monitoring and prediction of spatio-temporal patterns of forest fires across whole biomes; guarantees of additionality; avoiding leakage of fire-dependent agriculture; ensuring that responsibilities for fire management are fairly distributed; protection for rural livelihoods; and that any new activities result in positive outcomes for local people. © 2012 Elsevier Ltd.
Abstract.
Barlow J, Parry L, Gardner TA, Ferreira J, Aragão LEOC, Carmenta R, Berenguer E, Vieira ICG, Souza C, Cochrane MA, et al (2012). The critical importance of considering fire in REDD+ programs. Biological Conservation
Feldpausch TR, Lloyd J, Lewis SL, Brienen RJW, Gloor M, Monteagudo Mendoza A, Lopez-Gonzalez G, Banin L, Abu Salim K, Affum-Baffoe K, et al (2012). Tree height integrated into pantropical forest biomass estimates.
BIOGEOSCIENCES,
9(8), 3381-3403.
Author URL.
Ruhoff AL, Collischonn W, Paz AR, Rocha HR, Aragao LEOC, Malhi Y, Mu Q, Running SW (2012). Validation of the global evapotranspiration algorithm (MOD16) in two contrasting tropical land cover types.
IAHS-AISH Publication,
352, 128-131.
Abstract:
Validation of the global evapotranspiration algorithm (MOD16) in two contrasting tropical land cover types
This article presents results from NASA's EOS MOD 16 Project, which aims to estimate global evapotranspiration (ET) using remote sensing and meteorological data. Our specific objective in this study was to evaluate the accuracy of the newly improved MOD 16 algorithm at the Rio Grande basin, southern Brazil, using (i) ET observations at two eddy covariance (EC) flux tower sites in different land covers (savanna and sugar cane plantations) and (ii) ET estimations from hydrologicai model during 2001. Our results show that MOD 16 8 d average, monthly ET and annual ET values are consistent with observations of the two EC sites and the hydrologicai model. The RMSE and bias analyses indicate that the model overestimates ET values for savannas and underestimates these values for the sugar cane and the whole basin average. Estimates are very consistent in the dry season, while the larger prediction errors occur in the wet season. Copyright © 2012 IAHS Press.
Abstract.
2011
Anderson LO, Aragão LOC, Shimabukuro YE, Almeida S, Huete A (2011). Fraction images for monitoring intra-annual phenology of different vegetation physiognomies in Amazonia.
International Journal of Remote Sensing,
32(2), 387-408.
Abstract:
Fraction images for monitoring intra-annual phenology of different vegetation physiognomies in Amazonia
In this study we investigate the potential of fraction images derived from a linear spectral mixture model to detect vegetation phenology in Amazonia, and evaluate their relationships with the Moderate Resolution Imaging Spectroradiometer (MODIS) vegetation indices. Time series ofMODIS 250-m data over three contrasting land cover types in the Amazon were used in conjunction with rainfall data, a land covermap and a forest inventory survey to support the interpretation of our findings. Each vegetation physiognomy was characterized by a particular intra-annual variability detected by a combination of the fraction images. Both vegetation and shade fractions were important to evaluate the seasonality of the open tropical forest (OTF). The association of these results with forest inventory data and the literature suggests that Enhanced Vegetation Index (EVI) and vegetation fraction images are sensitive to structural changes in the canopy of OTF. In cerrado grassland (CG) the phenology was better characterized by combined soil and vegetation fractions. Soybean (SB) areas were characterized by the highest ranges in the vegetation and soil fraction images. Vegetation fraction and vegetation indices for the OTF showed a significant positive relationship with EVI but not with Normalized Difference Vegetation Index (NDVI). Significant relationships for vegetation fraction and vegetation indices were also found for the CG and soybean areas. In contrast to vegetation index approaches to monitoring phenology, fraction images provide additional information that allows amore comprehensive exploration of the spectral and structural changes in vegetation formations. © 2011 Taylor & Francis.
Abstract.
Bradley AV, Gerard FF, Barbier N, Weedon GP, Anderson LO, Huntingford C, Aragão LEOC, Zelazowski P, Arai E (2011). Relationships between phenology, radiation and precipitation in the Amazon region.
Global Change Biology,
17(6), 2245-2260.
Abstract:
Relationships between phenology, radiation and precipitation in the Amazon region
In tropical areas, Dynamic Global Vegetation Models (DGVMs) still have deficiencies in simulating the timing of vegetation phenology. To start addressing this problem, standard Fourier-based methods are applied to aerosol screened monthly remotely sensed phenology time series (Enhanced Vegetation Index, EVI) and two major driving factors of phenology: solar radiation and precipitation (for March 2000 through December 2006 over northern South America). At 1 × 1km scale using, power (or variance) spectra on good quality aerosol screened time series, annual cycles in EVI are detected across 58.24% of the study area, the strongest (largest amplitude) occurring in the savanna. Terra Firme forest have weak but significant annual cycles in comparison with savannas because of the heterogeneity of vegetation and nonsynchronous phenological events within 1 × 1km scale pixels. Significant annual cycles for radiation and precipitation account for 86% and 90% of the region, respectively, with different spatial patterns to phenology. Cross-spectral analysis was used to compare separately radiation with phenology/EVI, precipitation with phenology/EVI and radiation with precipitation. Overall the majority of the Terra Firme forest appears to have radiation as the driver of phenology (either radiation is in phase or leading phenology/EVI at the annual scale). These results are in agreement with previous research, although in Acre, central and eastern Peru and northern Bolivia there is a coexistence of 'in phase' precipitation over Terra Firme forest. In contrast in most areas of savanna precipitation appears to be a driver and savanna areas experiencing an inverse (antiphase) relationship between radiation and phenology is consistent with inhibited grassland growth due to soil moisture limitation. The resulting maps provide a better spatial understanding of phenology-driver relationships offering a bench mark to parameterize ecological models. © 2011 Blackwell Publishing Ltd.
Abstract.
Barlow J, Ewers RM, Anderson L, Aragao LEOC, Baker TR, Boyd E, Feldpausch TR, Gloor E, Hall A, Malhi Y, et al (2011). Using learning networks to understand complex systems: a case study of biological, geophysical and social research in the Amazon.
Biol Rev Camb Philos Soc,
86(2), 457-474.
Abstract:
Using learning networks to understand complex systems: a case study of biological, geophysical and social research in the Amazon.
Developing high-quality scientific research will be most effective if research communities with diverse skills and interests are able to share information and knowledge, are aware of the major challenges across disciplines, and can exploit economies of scale to provide robust answers and better inform policy. We evaluate opportunities and challenges facing the development of a more interactive research environment by developing an interdisciplinary synthesis of research on a single geographic region. We focus on the Amazon as it is of enormous regional and global environmental importance and faces a highly uncertain future. To take stock of existing knowledge and provide a framework for analysis we present a set of mini-reviews from fourteen different areas of research, encompassing taxonomy, biodiversity, biogeography, vegetation dynamics, landscape ecology, earth-atmosphere interactions, ecosystem processes, fire, deforestation dynamics, hydrology, hunting, conservation planning, livelihoods, and payments for ecosystem services. Each review highlights the current state of knowledge and identifies research priorities, including major challenges and opportunities. We show that while substantial progress is being made across many areas of scientific research, our understanding of specific issues is often dependent on knowledge from other disciplines. Accelerating the acquisition of reliable and contextualized knowledge about the fate of complex pristine and modified ecosystems is partly dependent on our ability to exploit economies of scale in shared resources and technical expertise, recognise and make explicit interconnections and feedbacks among sub-disciplines, increase the temporal and spatial scale of existing studies, and improve the dissemination of scientific findings to policy makers and society at large. Enhancing interaction among research efforts is vital if we are to make the most of limited funds and overcome the challenges posed by addressing large-scale interdisciplinary questions. Bringing together a diverse scientific community with a single geographic focus can help increase awareness of research questions both within and among disciplines, and reveal the opportunities that may exist for advancing acquisition of reliable knowledge. This approach could be useful for a variety of globally important scientific questions.
Abstract.
Author URL.
Mercado LM, Patiño S, Domingues TF, Fyllas NM, Weedon GP, Sitch S, Quesada CA, Phillips OL, Aragão LEOC, Malhi Y, et al (2011). Variations in Amazon forest productivity correlated with foliar nutrients and modelled rates of photosynthetic carbon supply.
Philos Trans R Soc Lond B Biol Sci,
366(1582), 3316-3329.
Abstract:
Variations in Amazon forest productivity correlated with foliar nutrients and modelled rates of photosynthetic carbon supply.
The rate of above-ground woody biomass production, W(P), in some western Amazon forests exceeds those in the east by a factor of 2 or more. Underlying causes may include climate, soil nutrient limitations and species composition. In this modelling paper, we explore the implications of allowing key nutrients such as N and P to constrain the photosynthesis of Amazon forests, and also we examine the relationship between modelled rates of photosynthesis and the observed gradients in W(P). We use a model with current understanding of the underpinning biochemical processes as affected by nutrient availability to assess: (i) the degree to which observed spatial variations in foliar [N] and [P] across Amazonia affect stand-level photosynthesis; and (ii) how these variations in forest photosynthetic carbon acquisition relate to the observed geographical patterns of stem growth across the Amazon Basin. We find nutrient availability to exert a strong effect on photosynthetic carbon gain across the Basin and to be a likely important contributor to the observed gradient in W(P). Phosphorus emerges as more important than nitrogen in accounting for the observed variations in productivity. Implications of these findings are discussed in the context of future tropical forests under a changing climate.
Abstract.
Author URL.
2010
Malhado ACM, Whittaker RJ, Malhi Y, Ladle RJ, Ter Steege H, Phillips O, AragãO LEOC, Baker TR, Arroyo L, Almeida S, et al (2010). Are compound leaves an adaptation to seasonal drought or to rapid growth? Evidence from the Amazon rain forest.
Global Ecology and Biogeography,
19(6), 852-862.
Abstract:
Are compound leaves an adaptation to seasonal drought or to rapid growth? Evidence from the Amazon rain forest
Aim to assess the hypotheses that compound leaves of trees in the Amazon forest are an adaptation to drought and/or rapid growth.Location Amazon rain forest, South America.Methods Genera from 137 permanent forest plots spread across Amazonia were classified into those with compound leaves and those with simple leaves. Metrics of compound leaf prevalence were then calculated for each plot and regression models that accounted for spatial autocorrelation were used to identify associations between climate variables and compound leaf structure. We also tested for associations between compound leaf structure and a variety of ecological variables related to life history and growth strategies, including wood density, annual increase in diameter and maximum height.Results One plant family, Fabaceae, accounts for 53% of compound-leaved individuals in the dataset, and has a geographical distribution strongly centred on north-east Amazonia. On exclusion of Fabaceae from the analysis we found no significant support for the seasonal drought hypothesis. However, we found evidence supporting the rapid growth hypothesis, with possession of compound leaves being associated with faster diameter growth rates and lower wood densities.Main conclusion This study provides evidence that possession of compound leaves constitutes one of a suite of traits and life-history strategies that promote rapid growth in rain forest trees. Our findings highlight the importance of carefully considering the geographical distribution of dominant taxa and spatial clustering of data points when inferring ecological causation from environment-trait associations. © 2010 Blackwell Publishing Ltd.
Abstract.
Phillips OL, van der Heijden G, Lewis SL, López-González G, Aragão LEOC, Lloyd J, Malhi Y, Monteagudo A, Almeida S, Dávila EA, et al (2010). Drought-mortality relationships for tropical forests.
New Phytol,
187(3), 631-646.
Abstract:
Drought-mortality relationships for tropical forests.
*The rich ecology of tropical forests is intimately tied to their moisture status. Multi-site syntheses can provide a macro-scale view of these linkages and their susceptibility to changing climates. Here, we report pan-tropical and regional-scale analyses of tree vulnerability to drought. We assembled available data on tropical forest tree stem mortality before, during, and after recent drought events, from 119 monitoring plots in 10 countries concentrated in Amazonia and Borneo. In most sites, larger trees are disproportionately at risk. At least within Amazonia, low wood density trees are also at greater risk of drought-associated mortality, independent of size. For comparable drought intensities, trees in Borneo are more vulnerable than trees in the Amazon. There is some evidence for lagged impacts of drought, with mortality rates remaining elevated 2 yr after the meteorological event is over. These findings indicate that repeated droughts would shift the functional composition of tropical forests toward smaller, denser-wooded trees. At very high drought intensities, the linear relationship between tree mortality and moisture stress apparently breaks down, suggesting the existence of moisture stress thresholds beyond which some tropical forests would suffer catastrophic tree mortality.
Abstract.
Author URL.
Metcalfe DB, Lobo-do-Vale R, Chaves MM, Maroco JP, Aragão LEOC, Malhi Y, Da Costa AL, Braga AP, Gonçalves PL, De Athaydes J, et al (2010). Impacts of experimentally imposed drought on leaf respiration and morphology in an Amazon rain forest.
Functional Ecology,
24(3), 524-533.
Abstract:
Impacts of experimentally imposed drought on leaf respiration and morphology in an Amazon rain forest
Summary: 1. The Amazon region may experience increasing moisture limitation over this century. Leaf dark respiration (R) is a key component of the Amazon rain forest carbon (C) cycle, but relatively little is known about its sensitivity to drought. 2. Here, we present measurements of R standardized to 25 °C and leaf morphology from different canopy heights over 5 years at a rain forest subject to a large-scale through-fall reduction (TFR) experiment, and nearby, unmodified Control forest, at the Caxiuanã reserve in the eastern Amazon. 3. In all five post-treatment measurement campaigns, mean R at 25 °C was elevated in the TFR forest compared to the Control forest experiencing normal rainfall. After 5 years of the TFR treatment, R per unit leaf area and mass had increased by 65% and 42%, respectively, relative to pre-treatment means. In contrast, leaf area index (L) in the TFR forest was consistently lower than the Control, falling by 23% compared to the pre-treatment mean, largely because of a decline in specific leaf area (S). 4. The consistent and significant effects of the TFR treatment on R, L and S suggest that severe drought events in the Amazon, of the kind that may occur more frequently in future, could cause a substantial increase in canopy carbon dioxide emissions from this ecosystem to the atmosphere. © 2010 the Authors. Journal compilation © 2010 British Ecological Society.
Abstract.
Poulter B, Aragão L, Heyder U, Gumpenberger M, Heinke J, Langerwisch F, Rammig A, Thonicke K, Cramer W (2010). Net biome production of the Amazon Basin in the 21st century.
Global Change Biology,
16(7), 2062-2075.
Abstract:
Net biome production of the Amazon Basin in the 21st century
Global change includes multiple stressors to natural ecosystems ranging from direct climate and land-use impacts to indirect degradation processes resulting from fire. Humid tropical forests are vulnerable to projected climate change and possible synergistic interactions with deforestation and fire, which may initiate a positive feedback to rising atmospheric CO2. Here, we present results from a multifactorial impact analysis that combined an ensemble of climate change models with feedbacks from deforestation and accidental fires to quantify changes in Amazon Basin carbon cycling. Using the LPJmL Dynamic Global Vegetation Model, we modelled spatio-temporal changes in net biome production (NBP); the difference between carbon fluxes from fire, deforestation, soil respiration and net primary production. By 2050, deforestation and fire (with no CO2 increase or climate change) resulted in carbon losses of 7.4-20.3 Pg C with the range of uncertainty depending on socio-economic storyline. During the same time period, interactions between climate and land use either compensated for carbon losses due to wetter climate and CO2 fertilization or exacerbated carbon losses from drought-induced forest mortality (-20.1 to +4.3 Pg C). By the end of the 21st century, depending on climate projection and the rate of deforestation (including its interaction with fire), carbon stocks either increased (+12.6 Pg C) or decreased (-40.6 Pg C). The synergistic effect of deforestation and fire with climate change contributed up to 26-36 Pg C of the overall decrease in carbon stocks. Agreement between climate projections (n=9), not accounting for deforestation and fire, in 2050 and 2098 was relatively low for the directional change in basin-wide NBP (19-37%) and aboveground live biomass (13-24%). The largest uncertainty resulted from climate projections, followed by implementation of ecosystem dynamics and deforestation. Our analysis partitions the drivers of tropical ecosystem change and is relevant for guiding mitigation and adaptation policy related to global change. © 2009 Blackwell Publishing Ltd.
Abstract.
Girardin CAJ, Malhi Y, Aragão LEOC, Mamani M, Huaraca Huasco W, Durand L, Feeley KJ, Rapp J, Silva-Espejo JE, Silman M, et al (2010). Net primary productivity allocation and cycling of carbon along a tropical forest elevational transect in the Peruvian Andes.
Global Change Biology,
16(12), 3176-3192.
Abstract:
Net primary productivity allocation and cycling of carbon along a tropical forest elevational transect in the Peruvian Andes
The net primary productivity, carbon (C) stocks and turnover rates (i.e. C dynamics) of tropical forests are an important aspect of the global C cycle. These variables have been investigated in lowland tropical forests, but they have rarely been studied in tropical montane forests (TMFs). This study examines spatial patterns of above- and belowground C dynamics along a transect ranging from lowland Amazonia to the high Andes in SE Peru. Fine root biomass values increased from 1.50MgCha-1 at 194m to 4.95 ± 0.62MgCha-1 at 3020m, reaching a maximum of 6.83 ± 1.13MgCha-1 at the 2020m elevation site. Aboveground biomass values decreased from 123.50MgCha-1 at 194m to 47.03MgCha-1 at 3020m. Mean annual belowground productivity was highest in the most fertile lowland plots (7.40 ± 1.00MgCha-1yr-1) and ranged between 3.43 ± 0.73 and 1.48 ± 0.40MgCha-1yr-1 in the premontane and montane plots. Mean annual aboveground productivity was estimated to vary between 9.50 ± 1.08MgCha-1yr-1 (210m) and 2.59 ± 0.40MgCha-1yr-1 (2020m), with consistently lower values observed in the cloud immersion zone of the montane forest. Fine root C residence time increased from 0.31 years in lowland Amazonia to 3.78 ± 0.81 years at 3020m and stem C residence time remained constant along the elevational transect, with a mean of 54 ± 4 years. The ratio of fine root biomass to stem biomass increased significantly with increasing elevation, whereas the allocation of net primary productivity above- and belowground remained approximately constant at all elevations. Although net primary productivity declined in the TMF, the partitioning of productivity between the ecosystem subcomponents remained the same in lowland, premontane and montane forests. © 2010 Blackwell Publishing Ltd.
Abstract.
Chave J, Navarrete D, Almeida S, Álvarez E, Aragão LEOC, Bonal D, Châtelet P, Silva-Espejo JE, Goret JY, Von Hildebrand P, et al (2010). Regional and seasonal patterns of litterfall in tropical South America.
Biogeosciences,
7(1), 43-55.
Abstract:
Regional and seasonal patterns of litterfall in tropical South America
The production of aboveground soft tissue represents an important share of total net primary production in tropical rain forests. Here we draw from a large number of published and unpublished datasets (n=Combining double low line81 sites) to assess the determinants of litterfall variation across South American tropical forests. We show that across old-growth tropical rainforests, litterfall averages 8.61±1.91 Mg ha-1 yr-1 (mean ± standard deviation, in dry mass units). Secondary forests have a lower annual litterfall than old-growth tropical forests with a mean of 8.01±3.41 Mg ha-1 yr-1. Annual litterfall shows no significant variation with total annual rainfall, either globally or within forest types. It does not vary consistently with soil type, except in the poorest soils (white sand soils), where litterfall is significantly lower than in other soil types (5.42±1.91 Mg ha-1 yr-1). We also study the determinants of litterfall seasonality, and find that it does not depend on annual rainfall or on soil type. However, litterfall seasonality is significantly positively correlated with rainfall seasonality. Finally, we assess how much carbon is stored in reproductive organs relative to photosynthetic organs. Mean leaf fall is 5.74±1.83 Mg ha-1 yr-1 (71% of total litterfall). Mean allocation into reproductive organs is 0.69±0.40 Mg ha-1 yr-1 (9% of total litterfall). The investment into reproductive organs divided by leaf litterfall increases with soil fertility, suggesting that on poor soils, the allocation to photosynthetic organs is prioritized over that to reproduction. Finally, we discuss the ecological and biogeochemical implications of these results.
Abstract.
Anderson LO, Malhi Y, Aragão LEOC, Ladle R, Arai E, Barbier N, Phillips O (2010). Remote sensing detection of droughts in Amazonian forest canopies.
New Phytol,
187(3), 733-750.
Abstract:
Remote sensing detection of droughts in Amazonian forest canopies.
*Remote sensing data are a key tool to assess large forested areas, where limitations such as accessibility and lack of field measurements are prevalent. Here, we have analysed datasets from moderate resolution imaging spectroradiometer (MODIS) satellite measurements and field data to assess the impacts of the 2005 drought in Amazonia. We combined vegetation indices (VI) and climatological variables to evaluate the spatiotemporal patterns associated with the 2005 drought, and explore the relationships between remotely-sensed indices and forest inventory data on tree mortality. There were differences in results based on c4 and c5 MODIS products. C5 VI showed no spatial relationship with rainfall or aerosol optical depth; however, distinct regions responded significantly to the increased radiation in 2005. The increase in the Enhanced VI (EVI) during 2005 showed a significant positive relationship (P < 0.07) with the increase of tree mortality. By contrast, the normalized difference water index (NDWI) exhibited a significant negative relationship (P < 0.09) with tree mortality. Previous studies have suggested that the increase in EVI during the 2005 drought was associated with a positive response of forest photosynthesis to changes in the radiation income. We discuss the evidence that this increase could be related to structural changes in the canopy.
Abstract.
Author URL.
Aragão LEOC, Shimabukuro YE (2010). Response to comment on "The incidence of fire in Amazonian forests with implications for REDD".
Science,
330(6011).
Abstract:
Response to comment on "The incidence of fire in Amazonian forests with implications for REDD"
Balch et al. suggest that the increased fire frequency reported in our study is principally due to post-deforestation activities. We present a new analysis demonstrating that for the majority of grid cells with positive fire trends, there is a low likelihood that these trends have resulted exclusively from post-deforestation activities. We therefore confirm that fires pose a growing threat to reducing emissions from deforestation and degradation (REDD) policies.
Abstract.
Metcalfe DB, Meir P, Aragão LEOC, Lobo-do-Vale R, Galbraith D, Fisher RA, Chaves MM, Maroco JP, da Costa ACL, de Almeida SS, et al (2010). Shifts in plant respiration and carbon use efficiency at a large-scale drought experiment in the eastern Amazon.
New Phytol,
187(3), 608-621.
Abstract:
Shifts in plant respiration and carbon use efficiency at a large-scale drought experiment in the eastern Amazon.
*The effects of drought on the Amazon rainforest are potentially large but remain poorly understood. Here, carbon (C) cycling after 5 yr of a large-scale through-fall exclusion (TFE) experiment excluding about 50% of incident rainfall from an eastern Amazon rainforest was compared with a nearby control plot. Principal C stocks and fluxes were intensively measured in 2005. Additional minor components were either quantified in later site measurements or derived from the available literature. Total ecosystem respiration (R(eco)) and total plant C expenditure (PCE, the sum of net primary productivity (NPP) and autotrophic respiration (R(auto))), were elevated on the TFE plot relative to the control. The increase in PCE and R(eco) was mainly caused by a rise in R(auto) from foliage and roots. Heterotrophic respiration did not differ substantially between plots. NPP was 2.4 +/- 1.4 t C ha(-1) yr(-1) lower on the TFE than the control. Ecosystem carbon use efficiency, the proportion of PCE invested in NPP, was lower in the TFE plot (0.24 +/- 0.04) than in the control (0.32 +/- 0.04). Drought caused by the TFE treatment appeared to drive fundamental shifts in ecosystem C cycling with potentially important consequences for long-term forest C storage.
Abstract.
Author URL.
Robertson AL, Malhi Y, Farfan-Amezquita F, Aragão LEOC, Silva Espejo JE, Robertson MA (2010). Stem respiration in tropical forests along an elevation gradient in the Amazon and Andes.
Global Change Biology,
16(12), 3193-3204.
Abstract:
Stem respiration in tropical forests along an elevation gradient in the Amazon and Andes
Autotrophic respiration involves the use of fixed carbon by plants for their own metabolism, resulting in the release of carbon dioxide as a by-product. Little is known of how autotrophic respiration components vary across environmental gradients, particularly in tropical ecosystems. Here, we present stem CO2 efflux data measured across an elevation transect spanning ca. 2800m in the Peruvian Amazon and Andes. Forest plots from five elevations were studied: 194, 210, 1000, 1500, and 3025masl Stem CO2 efflux (Rs) values from each plot were extrapolated to the 1-ha plot level. Mean Rs per unit stem surface area declined significantly with elevation, from 1.14±0.12 at 210m elevation to 0.62±0.09μmolCm-2s-1 at 3025m elevation. When adjusted for changing forest structure with elevation, this is equivalent to 6.45±1.12MgCha-1yr-1 at 210m elevation to 2.94±0.19MgCha-1yr-1 at 3025m elevation. We attempted to partition stem respiration into growth and maintenance respiration components for each site. Both growth and maintenance respiration rates per unit stem showed similar, moderately significant absolute declines with elevation, but the proportional decline in growth respiration rates was much greater. Stem area index (SAI) showed little trend along the transect, with declining tree stature at higher elevations being offset by an increased number of small trees. This trend in SAI is sensitive to changes in forest stature or size structure. In the context of rapid regional warming over the 21st century, such indirect, ecosystem-level temperature responses are likely to be as important as the direct effects of temperature on maintenance respiration rates. © 2010 Blackwell Publishing Ltd.
Abstract.
Aragão LEOC, Shimabukuro YE (2010). The incidence of fire in Amazonian forests with implications for REDD.
Science,
328(5983), 1275-1278.
Abstract:
The incidence of fire in Amazonian forests with implications for REDD.
Reducing emissions from deforestation and degradation (REDD) may curb carbon emissions, but the consequences for fire hazard are poorly understood. By analyzing satellite-derived deforestation and fire data from the Brazilian Amazon, we show that fire occurrence has increased in 59% of the area that has experienced reduced deforestation rates. Differences in fire frequencies across two land-use gradients reveal that fire-free land-management can substantially reduce fire incidence by as much as 69%. If sustainable fire-free land-management of deforested areas is not adopted in the REDD mechanism, then the carbon savings achieved by avoiding deforestation may be partially negated by increased emissions from fires.
Abstract.
Author URL.
2009
Arag̃o LEOC, Malhi Y, Metcalfe DB, Silva-Espejo JE, Jiménez E, Navarrete D, Almeida S, Costa ACL, Salinas N, Phillips OL, et al (2009). Above- and below-ground net primary productivity across ten Amazonian forests on contrasting soils.
Biogeosciences,
6(12), 2759-2778.
Abstract:
Above- and below-ground net primary productivity across ten Amazonian forests on contrasting soils
The net primary productivity (NPP) of tropical forests is one of the most important and least quantified components of the global carbon cycle. Most relevant studies have focused particularly on the quantification of the above-ground coarse wood productivity, and little is known about the carbon fluxes involved in other elements of the NPP, the partitioning of total NPP between its above- and below-ground components and the main environmental drivers of these patterns. In this study we quantify the above- and below-ground NPP of ten Amazonian forests to address two questions: (1) How do Amazonian forests allocate productivity among its above- and below-ground components? (2) How do soil and leaf nutrient status and soil texture affect the productivity of Amazonian forests? Using a standardized methodology to measure the major elements of productivity, we show that NPP varies between 9.3±1.3 Mg C ha-1 yr-1 (mean±standard error), at a white sand plot, and 17.0±1.4 Mg C ha-1 yr-1 at a very fertile Terra Preta site, with an overall average of 12.8±0.9 Mg C ha -1 yr-1. The studied forests allocate on average 64±3% and 36±3% of the total NPP to the above- and below-ground components, respectively. The ratio of above-ground and below-ground NPP is almost invariant with total NPP. Litterfall and fine root production both increase with total NPP, while stem production shows no overall trend. Total NPP tends to increase with soil phosphorus and leaf nitrogen status. However, allocation of NPP to below-ground shows no relationship to soil fertility, but appears to decrease with the increase of soil clay content.
Abstract.
Malhi Y, Aragão LEOC, Metcalfe DB, Paiva R, Quesada CA, Almeida S, Anderson L, Brando P, Chambers JQ, da Costa ACL, et al (2009). Comprehensive assessment of carbon productivity, allocation and storage in three Amazonian forests.
Global Change Biology,
15(5), 1255-1274.
Abstract:
Comprehensive assessment of carbon productivity, allocation and storage in three Amazonian forests
The allocation and cycling of carbon (C) within forests is an important component of the biospheric C cycle, but is particularly understudied within tropical forests. We synthesise reported and unpublished results from three lowland rainforest sites in Amazonia (in the regions of Manaus, Tapajós and Caxiuanã), all major sites of the Large-Scale Biosphere-Atmosphere Programme (LBA). We attempt a comprehensive synthesis of the C stocks, nutrient status and, particularly, the allocation and internal C dynamics of all three sites. The calculated net primary productivities (NPP) are 10.1 ± 1.4 MgC ha-1 yr-1 (Manaus), 14.4 ± 1.3 Mg Cha-1 yr-1 (Tapajós) and 10.0 ± 1.2MgCha-1 yr-1 (Caxiuanã). All errors bars report standard errors. Soil and leaf nutrient analyses indicate that Tapajós has significantly more plant-available phosphorus and calcium. Autotrophic respiration at all three sites (14.9-21.4 Mg Cha yr-1) is more challenging to measure, with the largest component and greatest source of uncertainty being leaf dark respiration. Comparison of measured soil respiration with that predicted from C cycling measurements provides an independent constraint. It shows general good agreement at all three sites, with perhaps some evidence for measured soil respiration being less than expected. Twenty to thirty percent of fixed C is allocated belowground. Comparison of gross primary productivity (GPP), derived from ecosystem flux measurements with that derived from component studies (NPP plus autotrophic respiration) provides an additional crosscheck. The two approaches are in good agreement, giving increased confidence in both approaches to estimating GPP. The ecosystem carbon-use efficiency (CUEs), the ratio of NPP to GPP, is similar at Manaus (0.34 ± 0.10) and Caxiuanã (0.32 ± 0.07), but may be higher at Tapajós (0.49 ± 0.16), although the difference is not significant. Old growth or infertile tropical forests may have low CUE compared with recently disturbed and/or fertile forests. © Journal compilation © 2009 Blackwell Publishing.
Abstract.
Phillips OL, Aragão LEOC, Lewis SL, Fisher JB, Lloyd J, López-González G, Malhi Y, Monteagudo A, Peacock J, Quesada CA, et al (2009). Drought sensitivity of the Amazon rainforest.
Science,
323(5919), 1344-1347.
Abstract:
Drought sensitivity of the Amazon rainforest.
Amazon forests are a key but poorly understood component of the global carbon cycle. If, as anticipated, they dry this century, they might accelerate climate change through carbon losses and changed surface energy balances. We used records from multiple long-term monitoring plots across Amazonia to assess forest responses to the intense 2005 drought, a possible analog of future events. Affected forest lost biomass, reversing a large long-term carbon sink, with the greatest impacts observed where the dry season was unusually intense. Relative to pre-2005 conditions, forest subjected to a 100-millimeter increase in water deficit lost 5.3 megagrams of aboveground biomass of carbon per hectare. The drought had a total biomass carbon impact of 1.2 to 1.6 petagrams (1.2 x 10(15) to 1.6 x 10(15) grams). Amazon forests therefore appear vulnerable to increasing moisture stress, with the potential for large carbon losses to exert feedback on climate change.
Abstract.
Author URL.
Aragao LEOC (2009). Environmental Justice in Latin America: Problems, Promise, and Practice.
BULLETIN OF LATIN AMERICAN RESEARCH,
28(2), 302-303.
Author URL.
Malhi Y, Aragão LEOC, Galbraith D, Huntingford C, Fisher R, Zelazowski P, Sitch S, McSweeney C, Meir P (2009). Exploring the likelihood and mechanism of a climate-change-induced dieback of the Amazon rainforest.
Proc Natl Acad Sci U S A,
106(49), 20610-20615.
Abstract:
Exploring the likelihood and mechanism of a climate-change-induced dieback of the Amazon rainforest.
We examine the evidence for the possibility that 21st-century climate change may cause a large-scale "dieback" or degradation of Amazonian rainforest. We employ a new framework for evaluating the rainfall regime of tropical forests and from this deduce precipitation-based boundaries for current forest viability. We then examine climate simulations by 19 global climate models (GCMs) in this context and find that most tend to underestimate current rainfall. GCMs also vary greatly in their projections of future climate change in Amazonia. We attempt to take into account the differences between GCM-simulated and observed rainfall regimes in the 20th century. Our analysis suggests that dry-season water stress is likely to increase in E. Amazonia over the 21st century, but the region tends toward a climate more appropriate to seasonal forest than to savanna. These seasonal forests may be resilient to seasonal drought but are likely to face intensified water stress caused by higher temperatures and to be vulnerable to fires, which are at present naturally rare in much of Amazonia. The spread of fire ignition associated with advancing deforestation, logging, and fragmentation may act as nucleation points that trigger the transition of these seasonal forests into fire-dominated, low biomass forests. Conversely, deliberate limitation of deforestation and fire may be an effective intervention to maintain Amazonian forest resilience in the face of imposed 21st-century climate change. Such intervention may be enough to navigate E. Amazonia away from a possible "tipping point," beyond which extensive rainforest would become unsustainable.
Abstract.
Author URL.
Anderson LO, Malhi Y, Ladle RJ, Aragão LEOC, Shimabukuro Y, Phillips OL, Baker T, Costa ACL, Espejo JS, Higuchi N, et al (2009). Influence of landscape heterogeneity on spatial patterns of wood productivity, wood specific density and above ground biomass in Amazonia.
Biogeosciences,
6(9), 1883-1902.
Abstract:
Influence of landscape heterogeneity on spatial patterns of wood productivity, wood specific density and above ground biomass in Amazonia
Long-term studies using the RAINFOR network of forest plots have generated significant insights into the spatial and temporal dynamics of forest carbon cycling in Amazonia. In this work, we map and explore the landscape context of several major RAINFOR plot clusters using Landsat ETM+ satellite data. In particular, we explore how representative the plots are of their landscape context, and test whether bias in plot location within landscapes may be influencing the regional mean values obtained for important forest biophysical parameters. Specifically, we evaluate whether the regional variations in wood productivity, wood specific density and above ground biomass derived from the RAINFOR network could be driven by systematic and unintentional biases in plot location. Remote sensing data covering 45 field plots were aggregated to generate landscape maps to identify the specific physiognomy of the plots. In the Landsat ETM+ data, it was possible to spectrally differentiate three types of terra firme forest, three types of forests over Paleovarzea geomorphologycal formation, two types of bamboo-dominated forest, palm forest, Heliconia monodominant vegetation, swamp forest, disturbed forests and land use areas. Overall, the plots were generally representative of the forest physiognomies in the landscape in which they are located. Furthermore, the analysis supports the observed regional trends in those important forest parameters. This study demonstrates the utility of landscape scale analysis of forest physiognomies for validating and supporting the finds of plot based studies. Moreover, the more precise geolocation of many key RAINFOR plot clusters achieved during this research provides important contextual information for studies employing the RAINFOR database.
Abstract.
Anderson LO, Malhi Y, Ladle RJ, Aragão LEOC, Shimabukuro Y, Phillips OL, Baker T, Costa ACL, Espejo JS, Higuchi N, et al (2009). Influence of landscape heterogeneity on spatial patterns of wood productivity, wood specific density and above ground biomass in Amazonia. Biogeosciences Discussions, 6(1), 2039-2083.
Malhado ACM, Whittaker RJ, Malhi Y, Ladle RJ, Ter Steege H, Butt N, Aragao LEOC, Quesada CA, Murakami-Araujo A, Phillips OL, et al (2009). Spatial distribution and functional significance of leaf lamina shape in Amazonian forest trees.
Biogeosciences,
6(8), 1577-1590.
Abstract:
Spatial distribution and functional significance of leaf lamina shape in Amazonian forest trees
Leaves in tropical forests come in an enormous variety of sizes and shapes, each of which can be ultimately viewed as an adaptation to the complex problem of optimising the capture of light for photosynthesis. However, the fact that many different shape "strategies" coexist within a habitat demonstrate that there are many other intrinsic and extrinsic factors involved, such as the differential investment in support tissues required for different leaf lamina shapes. Here, we take a macrogeographic approach to understanding the function of different lamina shape categories. Specifically, we use 106 permanent plots spread across the Amazon rainforest basin to: 1) describe the geographic distribution of some simple metrics of lamina shape in plots from across Amazonia, and; 2) identify and quantify relationships between key environmental parameters and lamina shape in tropical forests. Because the plots are not randomly distributed across the study area, achieving this latter objective requires the use of statistics that can account for spatial auto-correlation. We found that between 60-70% of the 2791 species and 83 908 individual trees in the dataset could be classified as having elliptic leaves (=the widest part of the leaf is on an axis in the middle fifth of the long axis of the leaf). Furthermore, the average Amazonian tree leaf is 2.5 times longer than it is wide and has an entire margin. Contrary to theoretical expectations we found little support for the hypothesis that narrow leaves are an adaptation to dry conditions. However, we did find strong regional patterns in leaf lamina length-width ratios and several significant correlations with precipitation variables suggesting that water availability may be exerting an as yet unrecognised selective pressure on leaf shape of rainforest trees. Some support was found for the hypothesis that narrow leaves are an adaptation to low nutrient soils. Furthermore, we found a strong correlation between the proportion of trees with non-entire laminas (dissected, toothed, etc.) and mean annual temperature once again supporting the well documented association that provides a basis for reconstructing past temperature regimes.
Abstract.
Malhado ACM, Whittaker RJ, Malhi Y, Ladle RJ, Ter Steege H, Aragão LEOC, Quesada CA, Araujo AM, Phillips OL, Peacock J, et al (2009). Spatial distribution and functional significance of leaf lamina shape in Amazonian forest trees. Biogeosciences Discussions, 6(1), 1837-1874.
Malhado ACM, Malhi Y, Whittaker RJ, Ladle RJ, Ter Steege H, Aragão LEOC, Quesada CA, Araujo-Murakami A, Phillips OL, Peacock J, et al (2009). Spatial trends in leaf size of Amazonian rainforest trees. Biogeosciences Discussions, 6(1), 2125-2162.
Malhado ACM, Malhi Y, Whittaker RJ, Ladle RJ, Ter Steege H, Phillips OL, Butt N, Aragão LEOC, Quesada CA, Araujo-Murakami A, et al (2009). Spatial trends in leaf size of amazonian rainforest trees.
Biogeosciences,
6(8), 1563-1576.
Abstract:
Spatial trends in leaf size of amazonian rainforest trees
Leaf size influences many aspects of tree function such as rates of transpiration and photosynthesis and, consequently, often varies in a predictable way in response to environmental gradients. The recent development of pan-Amazonian databases based on permanent botanical plots has now made it possible to assess trends in leaf size across environmental gradients in Amazonia. Previous plot-based studies have shown that the community structure of Amazonian trees breaks down into at least two major ecological gradients corresponding with variations in soil fertility (decreasing from southwest to northeast) and length of the dry season (increasing from northwest to south and east). Here we describe the geographic distribution of leaf size categories based on 121 plots distributed across eight South American countries. We find that the Amazon forest is predominantly populated by tree species and individuals in the mesophyll size class (20.25-182.25 cm2). The geographic distribution of species and individuals with large leaves (gt;20.25 cm2) is complex but is generally characterized by a higher proportion of such trees in the northwest of the region. Spatially corrected regressions reveal weak correlations between the proportion of large-leaved species and metrics of water availability. We also find a significant negative relationship between leaf size and wood density.
Abstract.
Bradley A, Gerard F, Barbier N, Weedon G, Huntingford C, Zelazowski P, Anderson L, De Aragão LEOC, Kaduk J (2009). Template phenology for vegetation models.
International Geoscience and Remote Sensing Symposium (IGARSS),
4, 1042-1045.
Abstract:
Template phenology for vegetation models
To assist the representation of phenology in vegetation models we created several templates of phenology-driver relations by characterizing the annual phase differences between phenology and two phenology drivers. We did this using the results of a cross spectral analysis of MODIS EVI with radiation (CPTEC) and with precipitation (TRMM). Four phase ranges were identified for phenology-radiation and three phase ranges for phenologyprecipitation. These ranges were classified and mapped together into 12 zones of our study area where particular phase relationships coincided. Around ∼25% area was in phase with radiation, with varying phase ranges of precipitation, and ∼16 % was in phase with precipitation with varying phase ranges of radiation. For each zone we conceptualized the phenology-driver relationships with phase lagged curves. The phase timing of these plots matched well with average time series plots from the same zones, but more work is needed on the representation of amplitude. ©2009 IEEE.
Abstract.
Malhi Y, Saatchi S, Girardin C, Aragão LEOC (2009). The production, storage, and flow of carbon in Amazonian forests.
Geophysical Monograph Series,
186, 355-372.
Abstract:
The production, storage, and flow of carbon in Amazonian forests
The carbon stores and dynamics of tropical forests are the subject of major international scientific and policy attention. Research associated with the Large-Scale Biosphere-Atmosphere Experiment in Amazonia (LBA) has generated substantial advances in our understanding of the cycling of carbon at selected forest sites in Brazilian Amazonia and generated new insights into how these processes may vary across the wider Amazonian region. Here we report on aspects of this new understanding. We present, in particular, a comprehensive synthesis of carbon cycling in three focal LBA sites (Manaus, Tapajós, and Caxiuanã), drawing on studies of productivity, litterfall, respiration, physiology, and ecosystem fluxes. These studies are placed in the context of the wider Amazonian region by utilizing the results of the Amazon Forest Inventory Network (RAINFOR) and other forest plots. We discuss the basin-wide distribution of forest biomass derived by combining these plots and a suite of satellite data, and examine the dynamics of carbon cycling in the context of regional carbon stores in the forest. Particular attention is drawn to the strong relationship between forest productivity and turnover, which suggests that higher levels of forest productivity increase forest dynamism rather than forest biomass. We conclude by discussing what the scientific priorities should be for a synthetic region-wide understanding of the carbon dynamics and stores of Amazonian forests. © Copyright 2009 by the American Geophysical Union.
Abstract.
2008
Bradley A, Gerard F, Barbier N, Zelazowski P, Weedon G, Huntingford C, Anderson L, De Aragão LEOC (2008). Exploring the biophysical drivers of amazon phenology: Preparing data sets to improve dynamic global vegetation models.
International Geoscience and Remote Sensing Symposium (IGARSS),
2(1).
Abstract:
Exploring the biophysical drivers of amazon phenology: Preparing data sets to improve dynamic global vegetation models
We explore the relative influence of biophysical drivers on phenology to assist validation and parameterization of Dynamic Global Vegetation Models. Using 6.8 years of MODIS data we created a vegetation index time series to map the spatial variability of vegetation phenology in the Amazon. TRMM and CERES data were used as a measure of two biophysical variables, precipitation and net radiation respectively. Using a Fourier transform and cross spectral analysis two aspects were considered from these data, the coincidence of: (A) spatial patterns, presence and strength in the annual cycle, and (B) the coherency and phase differences between the phenology and the biophysical variables. Using the Amazon as a study area we find that the coincidence between phenology and the drivers in annual power strength was not linear and in an area of high coherency we found radiation and phenology was almost in phase, whilst precipitation was not. The correspondence of slightly subdued annual phenology with strong annual radiation indicated that other drivers also influence the strength of the phenology. © 2008 IEEE.
Abstract.
Aragão LEOC, Malhi Y, Barbier N, Lima A, Shimabukuro Y, Anderson L, Saatchi S (2008). Interactions between rainfall, deforestation and fires during recent years in the Brazilian Amazonia.
Philos Trans R Soc Lond B Biol Sci,
363(1498), 1779-1785.
Abstract:
Interactions between rainfall, deforestation and fires during recent years in the Brazilian Amazonia.
Understanding the interplay between climate and land-use dynamics is a fundamental concern for assessing the vulnerability of Amazonia to climate change. In this study, we analyse satellite-derived monthly and annual time series of rainfall, fires and deforestation to explicitly quantify the seasonal patterns and relationships between these three variables, with a particular focus on the Amazonian drought of 2005. Our results demonstrate a marked seasonality with one peak per year for all variables analysed, except deforestation. For the annual cycle, we found correlations above 90% with a time lag between variables. Deforestation and fires reach the highest values three and six months, respectively, after the peak of the rainy season. The cumulative number of hot pixels was linearly related to the size of the area deforested annually from 1998 to 2004 (r2=0.84, p=0.004). During the 2005 drought, the number of hot pixels increased 43% in relation to the expected value for a similar deforested area (approx. 19000km2). We demonstrated that anthropogenic forcing, such as land-use change, is decisive in determining the seasonality and annual patterns of fire occurrence. Moreover, droughts can significantly increase the number of fires in the region even with decreased deforestation rates. We may expect that the ongoing deforestation, currently based on slash and burn procedures, and the use of fires for land management in Amazonia will intensify the impact of droughts associated with natural climate variability or human-induced climate change and, therefore, a large area of forest edge will be under increased risk of fires.
Abstract.
Author URL.
Metcalfe D, Meir P, Aragão LEOC, da Costa A, Almeida S, Braga A, Gonçalves P, Athaydes J, Malhi Y, Williams M, et al (2008). Sample sizes for estimating key ecosystem characteristics in a tropical terra firme rainforest.
Forest Ecology and Management,
255(3-4), 558-566.
Abstract:
Sample sizes for estimating key ecosystem characteristics in a tropical terra firme rainforest
This study evaluated the sample sizes necessary to estimate several soil and vegetation characteristics within 10% confidence intervals with 95% probability in three terra firme tropical rainforest sites. Across all three plots, the most spatially heterogeneous variables were measurements of total standing crop root mass, ground surface litter mass, litter fall, root growth and soil respiration which required, on average, 152, 105, 52, 45 and 28 samples, respectively to estimate mean values within 10% confidence intervals with 95% probability. Leaf area index measurements integrated canopy characteristics over a relatively large spatial area and therefore only required five samples, on average, to achieve the same degree of precision. Measurements of soil temperature, moisture, carbon and nitrogen content in the surface 30 cm soil layer displayed the lowest degree of spatial variation: requiring a maximum of seven samples to estimate mean values within 10% confidence intervals with 95% probability. This study, together with a review of data from similar ecosystems, suggests that standing crop root mass, root growth, litter fall and ground surface litter mass are usually acutely under-sampled, which could impede detection and interpretation of patterns and processes in these potentially important ecosystem characteristics. This information may assist researchers to design effective sampling strategies for field experiments, particularly in tropical forests. © 2007 Elsevier B.V. All rights reserved.
Abstract.
Metcalfe DB, Meir P, Aragão LEOC, Da Costa ACL, Braga AP, Gonçalves PHL, De Athaydes Silva Junior J, De Almeida SS, Dawson LA, Malhi Y, et al (2008). The effects of water availability on root growth and morphology in an Amazon rainforest.
Plant and Soil,
311(1-2), 189-199.
Abstract:
The effects of water availability on root growth and morphology in an Amazon rainforest
This study examined how root growth and morphology were affected by variation in soil moisture at four Amazon rainforest sites with contrasting vegetation and soil types. Mean annual site root mass, length and surface area growth ranged between 3-7 t ha-1, 2-4 km m-2 and 8-12 m2 m-2 respectively. Mean site specific root length and surface area varied between 8-10 km kg-1 and 24-34 m2 kg-1. Growth of root mass, length and surface area was lower when soil water was depleted (P
Abstract.
2007
Metcalfe DB, Williams M, Aragão LEOC, Da Costa ACL, De Almeida SS, Braga AP, Gonçalves PHL, De Athaydes J, Junior S, Malhi Y, et al (2007). A method for extracting plant roots from soil which facilitates rapid sample processing without compromising measurement accuracy.
New Phytol,
174(3), 697-703.
Abstract:
A method for extracting plant roots from soil which facilitates rapid sample processing without compromising measurement accuracy.
This study evaluates a novel method for extracting roots from soil samples and applies it to estimate standing crop root mass (+/- confidence intervals) in an eastern Amazon rainforest. Roots were manually extracted from soil cores over a period of 40 min, which was split into 10 min time intervals. The pattern of cumulative extraction over time was used to predict root extraction beyond 40 min. A maximum-likelihood approach was used to calculate confidence intervals. The temporal prediction method added 21-32% to initial estimates of standing crop root mass. According to predictions, complete manual root extraction from 18 samples would have taken c. 239 h, compared with 12 h using the prediction method. Uncertainties (percentage difference between mean, and 10th and 90th percentiles) introduced by the prediction method were small (12-15%), compared with uncertainties caused by spatial variation in root mass (72-191%, for nine samples per plot surveyed). This method provides a way of increasing the number of root samples processed per unit time, without compromising measurement accuracy.
Abstract.
Author URL.
Luyssaert S, Inglima I, Jung M, Richardson AD, Reichstein M, Papale D, Piao SL, Schulze ED, Wingate L, Matteucci G, et al (2007). CO<inf>2</inf> balance of boreal, temperate, and tropical forests derived from a global database.
Global Change Biology,
13(12), 2509-2537.
Abstract:
CO2 balance of boreal, temperate, and tropical forests derived from a global database
Terrestrial ecosystems sequester 2.1 Pg of atmospheric carbon annually. A large amount of the terrestrial sink is realized by forests. However, considerable uncertainties remain regarding the fate of this carbon over both short and long timescales. Relevant data to address these uncertainties are being collected at many sites around the world, but syntheses of these data are still sparse. To facilitate future synthesis activities, we have assembled a comprehensive global database for forest ecosystems, which includes carbon budget variables (fluxes and stocks), ecosystem traits (e.g. leaf area index, age), as well as ancillary site information such as management regime, climate, and soil characteristics. This publicly available database can be used to quantify global, regional or biome-specific carbon budgets; to re-examine established relationships; to test emerging hypotheses about ecosystem functioning [e.g. a constant net ecosystem production (NEP) to gross primary production (GPP) ratio]; and as benchmarks for model evaluations. In this paper, we present the first analysis of this database. We discuss the climatic influences on GPP, net primary production (NPP) and NEP and present the CO2 balances for boreal, temperate, and tropical forest biomes based on micrometeorological, ecophysiological, and biometric flux and inventory estimates. Globally, GPP of forests benefited from higher temperatures and precipitation whereas NPP saturated above either a threshold of 1500 mm precipitation or a mean annual temperature of 10 °C. The global pattern in NEP was insensitive to climate and is hypothesized to be mainly determined by nonclimatic conditions such as successional stage, management, site history, and site disturbance. In all biomes, closing the CO2 balance required the introduction of substantial biome-specific closure terms. Nonclosure was taken as an indication that respiratory processes, advection, and non-CO2 carbon fluxes are not presently being adequately accounted for. © 2007 Blackwell Publishing Ltd.
Abstract.
Metcalfe DB, Meir P, Aragão LEOC, Malhi Y, da Costa ACL, Braga A, Gonçalves PHL, de Athaydes J, de Almeida SS, Williams M, et al (2007). Factors controlling spatio-temporal variation in carbon dioxide efflux from surface litter, roots, and soil organic matter at four rain forest sites in the eastern Amazon.
Journal of Geophysical Research: Biogeosciences,
112(4).
Abstract:
Factors controlling spatio-temporal variation in carbon dioxide efflux from surface litter, roots, and soil organic matter at four rain forest sites in the eastern Amazon
This study explored biotic and abiotic causes for spatio-temporal variation in soil respiration from surface litter, roots, and soil organic matter over one year at four rain forest sites with different vegetation structures and soil types in the eastern Amazon, Brazil. Estimated mean annual soil respiration varied between 13-17 t C ha-1 yr-1, which was partitioned into 0-2 t C ha-1 yr-1 from litter, 6-9 t C ha-1 yr-1 from roots, and 5-6 t C ha-1 yr-1 from soil organic matter. Litter contribution showed no clear seasonal change, though experimental precipitation exclusion over a one-hectare area was associated with a ten-fold reduction in litter respiration relative to unmodified sites. The estimated mean contribution of soil organic matter respiration fell, from 49% during the wet season to 32% in the dry season, while root respiration contribution increased from 42% in the wet season to 61% during the dry season. Spatial variation in respiration from soil, litter, roots, and soil organic matter was not explained by volumetric soil moisture or temperature. Instead, spatial heterogeneity in litter and root mass accounted for 44% of observed spatial variation in soil respiration (p < 0.001). In particular, variation in litter respiration per unit mass and root mass accounted for much of the observed variation in respiration from litter and roots, respectively, and hence total soil respiration. This information about patterns of, and underlying controls on, respiration from different soil components should assist attempts to accurately model soil carbon dioxide fluxes over space and time. Copyright 2007 by the American Geophysical Union.
Abstract.
Metcalfe DB, Meir P, Aragao LEOC, Malhi Y, da Costa ACL, Braga A, Goncalves PHL, de Athaydes J, de Almeida SS, Williams M, et al (2007). Factors controlling spatio-temporal variation in carbon dioxide efflux from surface litter, roots, and soil organic matter at four rain forest sites in the eastern Amazon.
JOURNAL OF GEOPHYSICAL RESEARCH-BIOGEOSCIENCES,
112(G4).
Author URL.
Aragão LEOC, Malhi Y, Roman-Cuesta RM, Saatchi S, Anderson LO, Shimabukuro YE (2007). Spatial patterns and fire response of recent Amazonian droughts.
Geophysical Research Letters,
34(7).
Abstract:
Spatial patterns and fire response of recent Amazonian droughts
There has been an increasing awareness of the possibility of climate change causing increased drought frequency in Amazonia, with ensuing impacts on ecosystems and human populations. This debate has been brought into focus by the 1997/1998 and 2005 Amazonian droughts. We analysed the spatial extent of these droughts and fire response to the 2005 drought with TRMM and NOAA-12 data, respectively. Both droughts had distinct fingerprints. The 2005 drought was characterized by its intensification throughout the dry season in south-western Amazonia. During 2005 the annual cumulative number of hot pixels in Amazonia increased 33% in relation to the 1999-2005 mean. In the Brazilian state of Acre, at the epicentre of the 2005 drought, the area of leakage forest fires was more than five times greater than the area directly deforested, Fire leakage into flammable forests may be the major agent of biome transformation in the event of increasing drought frequency. Copyright 2007 by the American Geophysical Union.
Abstract.
Anderson LO, Malhi Y, Aragão LEOC, Saatchi S (2007). Spatial patterns of the canopy stress during 2005 drought in Amazonia.
Abstract:
Spatial patterns of the canopy stress during 2005 drought in Amazonia
Abstract.
2006
Villela DM, Nascimento MT, De Aragão LEOC, Da Gama DM (2006). Effect of selective logging on forest structure and nutrient cycling in a seasonally dry Brazilian Atlantic forest.
Journal of Biogeography,
33(3), 506-516.
Abstract:
Effect of selective logging on forest structure and nutrient cycling in a seasonally dry Brazilian Atlantic forest
Aim: the Brazilian Atlantic forest covers c. 10% of its original extent, and some areas are still being logged. Although several ecological studies in Atlantic forest have been published over the past two to three decades, there has been little research on forest dynamics and there is a particular lack of information on the effects of disturbance. The aim of the present study was to assess the impact of selective logging on forest structure, floristic composition soil nutrients, litterfall and litter layer in a seasonally dry Atlantic forest. Location: the Mata do Carvão is located in the Guaxindiba Ecological Reserve in São Francisco do ltabapoana district (21°24′ S, 41°04′ W), Rio de Janeiro, Brazil. Methods: Four plots (50 x 50 m) were set up in 1995 in each of two stands: unlogged and logged. In each plot, all trees ≥ 10 cm d.b.h. were enumerated, identified and measured. Vouchers were lodged at UENF Herbarium. Five surface soil samples were collected in each plot in the dry season (in October 1995). Litterfall was collected in eight traps (0.50 m2) in each plot over a year from 14 November 1995 to 11 November 1996. The litter layer was sampled in eight quadrats (0.25 m2) in each plot in the dry and wet seasons. Soils were air-dried, sieved, and chemically analysed. The litter was dried (80°C), sorted into six fractions, weighed and bulked samples analysed for nutrients. Results: Forest stands did not differ in stem density and total basal area, with a total of 1137 individuals sampled in 1996 (564 unlogged and 573 logged), and a total basal area of 15 m2 (unlogged) and 13.0 m 2 (logged). However, unlogged stands had more large trees (≥ 30 cm in d.b.h.) and greater mean canopy height. Among the families, Rutaceae and Leguminosae were the most abundant families in both sites, although the Rutaceae had a higher density in unlogged and Leguminosae in the logged stand. The species diversity index was similar between stands. Late-successional species, such as Metrodorea nigra var. brevifolia and Paratecoma peroba, were less abundant in the logged stand. Selective logging did not affect nutrient concentrations in the soil or in the litter. However, quantities of the nutrients in the total litterfall and in the leaf litterfall and litter layer were higher in unlogged than in logged stands, mainly as a result of fallen M. nigra leaves. Metrodorea nigra was considered a key species in the nutrients dynamics in Carvão forest. Main conclusions: Despite the fact that effects on tree diversity and soil nutrients were not clear, selective logging in this Atlantic forest altered canopy structure, increased the relative abundance of some early-secondary species and decreased the litter input and stock of nutrients. Detailed information on the influence of logging on the distribution and structure of plant populations and in nutrient processes is fundamental for a sustainable logging system to be developed. © 2006 Blackwell Publishing Ltd.
Abstract.
Shimabukuro YE, Aragão LEOC, Williams M (2006). Meso-scale variability of soils and forest canopy properties is connected to geomorphologic features in Eastern Amazonia.
Abstract:
Meso-scale variability of soils and forest canopy properties is connected to geomorphologic features in Eastern Amazonia
Abstract.
Shimabukuro YE, Anderson LO, Aragão LEOC, Huete A (2006). Using fraction images to study natural land cover changes in the Amazon.
Abstract:
Using fraction images to study natural land cover changes in the Amazon
Abstract.
2005
Shabanov NV, Huang D, Yang W, Tan B, Knyazikhin Y, Myneni RB, Ahl DE, Gower ST, Huete AR, Aragão LEOC, et al (2005). Analysis and optimization of the MODIS leaf area index algorithm retrievals over broadleaf forests.
IEEE Transactions on Geoscience and Remote Sensing,
43(8), 1855-1865.
Abstract:
Analysis and optimization of the MODIS leaf area index algorithm retrievals over broadleaf forests
Broadleaf forest is a major type of Earth's land cover with the highest observable vegetation density. Retrievals of biophysical parameters, such as leaf area index (LAI), of broadleaf forests at global scale constitute a major challenge to modern remote sensing techniques in view of low sensitivity (saturation) of surface reflectances to such parameters over dense vegetation. The goal of the performed research is to demonstrate physical principles of LAI retrievals over broadleaf forests with the Moderate Resolution Imaging Spectroradiometer (MODIS) LAI algorithm and to establish a basis for algorithm refinement. To sample natural variability in biophysical parameters of broadleaf forests, we selected MODIS data subsets covering deciduous broadleaf forests of the eastern part of North America and evergreen broadleaf forests of Amazonia. The analysis of an annual course of the Terra MODIS Collection 4 LAI product over broadleaf forests indicated a low portion of best quality main radiative transfer-based algorithm retrievals and dominance of low-reliable backup algorithm retrievals during the growing season. We found that this retrieval anomaly was due to an inconsistency between simulated and MODIS surface reflectances. LAI retrievals over dense vegetation are mostly performed over a compact location in the spectral space of saturated surface reflectances, which need to be accurately modeled. New simulations were performed with the stochastic radiative transfer model, which poses high numerical accuracy at the condition of saturation. Separate sets of parameters of the LAI algorithm were generated for deciduous and evergreen broadleaf forests to account for the differences in the corresponding surface reflectance properties. The optimized algorithm closely captures physics of seasonal variations in surface reflectances and delivers a majority of LAI retrievals during a phonological cycle, consistent with field measurements. The analysis of the optimized retrievals indicates that the precision of MODIS surface reflectances, the natural variability, and mixture of species set a limit to improvements of the accuracy of LAI retrievals over broadleaf forests. © 2005 IEEE.
Abstract.
Aragão LEOC, Shimabukuro YE, Espírito-Santo FDB, Williams M (2005). Erratum: Spatial validation of the collection 4 MODIS LAI product in Eastern Amazonia(IEEE Transactions on Geoscience and Remote Sensing 2005 43:11 (2526-2534)). IEEE Transactions on Geoscience and Remote Sensing, 43(12).
Aragão LEOC, Shimabukuro YE, Espírito Santo FDB, Williams M (2005). Landscape pattern and spatial variability of leaf area index in Eastern Amazonia.
Forest Ecology and Management,
211(3), 240-256.
Abstract:
Landscape pattern and spatial variability of leaf area index in Eastern Amazonia
Uncertainties about the implications of land-cover heterogeneity on the Amazonian carbon (C) and water cycles are, in part, related to the lack of information about spatial patterns of key variables that control these fluxes at the regional scale. Leaf area index (LAI) is one of these key variables, regulating a number of ecosystem processes (e.g. evaporation, transpiration and photosynthesis). In order to generate a sampling strategy for LAI across a section of Amazonia, we generated a landscape unit (LU) map for the Tapajós region, Eastern Amazonia, as a basis for stratification. We identified seven primary forest classes, stratified according to vegetation and/or terrain characteristics, and one secondary forest class, covering 80% of the region. Primary forest units were the most representative, covering 62% of the total area. The LAI measurements were carried out in 13 selected LUs. In each LU, we marked out three 50 m x 50 m plots giving a total number of 39 plots (9.75 ha). A pair of LAI-2000 plant canopy analysers was used to estimate LAI. We recorded a total of 25 LAI measurements within each plot. We used the field data to verify the statistical distribution of LAI samples, analyse the LAI variability within and among sites, and show the influence of sample size on LAI variation and precision. The LAI showed a high coefficient of variation at the plot level (0.25 ha), from 5.2% to 23%, but this was reduced at the landscape unit level (three co-located plots, 1.8-12%). The level of precision was
Abstract.
Aragão LEOC, Shimabukuro YE, Espírito-Santo FDB, Williams M (2005). Spatial validation of the Collection 4 MODIS LAI product in Eastern Amazonia.
Abstract:
Spatial validation of the Collection 4 MODIS LAI product in Eastern Amazonia
Abstract.
Aragao LEOC, Shimabukuro YE, Espirito-Santo FDB, Williams M (2005). Spatial validation of the collection 4 MODIS LAI product in eastern amazonia (vol 43,pg 2526, 2005).
IEEE TRANSACTIONS ON GEOSCIENCE AND REMOTE SENSING,
43(12), 2973-2973.
Author URL.
2004
Shimabukuro YE, Aragão LEOC, Espírito-Santo FDB, Williams M (2004). Combining landsat ETM+ and terrain data for scaling up leaf area Index (LAI) in eastern amazon: an intercomparison with modis product.
Abstract:
Combining landsat ETM+ and terrain data for scaling up leaf area Index (LAI) in eastern amazon: an intercomparison with modis product
Abstract.
