Publications by year
2018
Tian J, He N, Kong W, Deng Y, Feng K, Green SM, Wang X, Zhou J, Kuzyakov Y, Yu G, et al (2018). Deforestation decreases spatial turnover and alters the network interactions in soil bacterial communities.
Soil Biology and Biochemistry,
123, 80-86.
Abstract:
Deforestation decreases spatial turnover and alters the network interactions in soil bacterial communities
Despite important progress in understanding the influence of deforestation on the bacterial α diversity and community structure at local scales, little is known about deforestation impacts in terms of spatial turnover and soil bacterial community network interactions, especially at regional or global scales. To address this research gap, we examined the bacterial spatial turnover rate and the species networks in paired primary and secondary forest soils along a 3700-km north-south transect in eastern China using high-throughput 16S rRNA gene sequencing. The spatial turnover rate of bacterial communities was higher in primary forests than in secondary, suggesting deforestation increased biotic homogenization at a large geographic scale. Multiple regression on matrices analysis revealed that both geographic distance and soil properties (especially soil pH and organic matter availability) strongly affected bacterial spatial turnover. Through the phylogenetic molecular ecological network approach, we demonstrate that the bacterial network of primary forests was more intricate than in secondary forests. This suggests that microbial species have greater niche-sharing and more interactions in primary forests as compared to secondary forests. On the other hand, the bacterial network in secondary forests was more modular, and the taxa tended to co-occur, with positive correlations accounting for 82% of all potential interactions. In conclusion, our findings demonstrate that anthropogenic deforestation has clear effects on bacterial spatial turnover and network interactions, with potential for serious consequences such as microbial diversity loss in primary forests.
Abstract.
Green SM, Baird AJ, Evans CD, Peacock M, Holden J, Chapman PJ, Smart RP (2018). Methane and carbon dioxide fluxes from open and blocked ditches in a blanket bog.
Plant and Soil,
424(1-2), 619-638.
Abstract:
Methane and carbon dioxide fluxes from open and blocked ditches in a blanket bog
Background and aims: There is growing interest in how the rewetting of drained peatlands can restart their carbon (C) sink function. However, there are few studies on the effect of ditch blocking on the within-ditch C balance. For a UK blanket bog we assessed how methane (CH4) emissions, net ecosystem exchange (NEE), and the overall greenhouse gas (GHG) balance expressed as carbon dioxide equivalents (CO2-e) responded to ditch blocking. Methods: We conducted a fully replicated field trial on a blanket bog in the Upper Conwy catchment, North Wales, UK. Twelve parallel ditches, that ran approximately downslope, were investigated. Four were left open, four had peat dams installed at intervals of a few metres along their length, and four were partially infilled with peat (reprofiled) and dammed. For a period of four years after blocking, we measured peatland-atmosphere fluxes of CH4 and CO2 within the ditches. Results: CH4 fluxes, NEE and overall GHG balance (expressed in terms of CO2-e) in the experimental area showed no evidence of varying systematically between the different types of ditch treatment (open, dammed, and reprofiled). In addition, there was little evidence that CH4 fluxes or CO2-e balance changed systematically with time since blocking. Conclusions: We found no evidence of consistent differences between blocking treatments in terms of CH4 emissions or overall CO2-e balance. There was high spatial and temporal variability in CO2 and CH4 fluxes within each treatment. We did not observe a post-blocking ‘spike’ in CH4 fluxes.
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Ma M, Gao Y, Song X, Green SM, Xiong B, Dungait JAJ, Peng T, Quine TA, Wen X, He N, et al (2018). Migration and leaching characteristics of base cation: indicating environmental effects on soil alkalinity in a karst area.
Environ Sci Pollut Res Int,
25(21), 20899-20910.
Abstract:
Migration and leaching characteristics of base cation: indicating environmental effects on soil alkalinity in a karst area.
In karst areas, rock dissolution often results in the development of underground networks, which act as subterranean pathways for rapid water and nutrient (and possibly soil) loss during precipitation events. Loss of soluble nutrients degrades surface soils and decreases net primary productivity, so it is important to establish flow pathways and quantify nutrient loss during rainfall events of different magnitudes. We conducted a simulated rainfall experiment in karst and nonkarst areas to compare the concentration of nutrients in surface and subsurface flow water and effects on soil alkalinity in three lithologic soil formations under five different rainfall intensity treatments. Compared with the nonkarst area, the runoff in subsurface flows and the proportion of nutrient loss in the subsurface flow are larger in the karst area and less affected by rain intensity. The maximum loss loads of calcium (Ca2+) and magnesium (Mg2+) ions were 32.9 and 19.8 kg ha-1, respectively. With the estimate of base cation loss loads in the China southern karst area under the rainfall intensity of 45 mm h-1, more than 80% of the base cation loss load occurred in the limestone karst area. Although the alkalinity leaching value in nonkarst was similar to that in the karst area under simulated rainfall conditions, its impact on the ecological environment was quite different.
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Sankar M, Green SM, Mishra PK, Snoalv JTC, Sharma NK, Karthikeyan K, Somasundaram J, Kadam DM, Dinesh D, Kumar S, et al (2018). Nationwide soil erosion assessment in India using radioisotope tracers Cs-137 and Pb-210: the need for fallout mapping.
CURRENT SCIENCE,
115(3), 388-390.
Author URL.
Li D, Zhang X, Green SM, Dungait JAJ, Wen X, Tang Y, Guo Z, Yang Y, Sun X, Quine TA, et al (2018). Nitrogen functional gene activity in soil profiles under progressive vegetative recovery after abandonment of agriculture at the Puding Karst Critical Zone Observatory, SW China.
Soil Biology and Biochemistry,
125, 93-102.
Abstract:
Nitrogen functional gene activity in soil profiles under progressive vegetative recovery after abandonment of agriculture at the Puding Karst Critical Zone Observatory, SW China
At the end of the 20th century, China launched the ‘Grain-for-Green’ Project (GGP) that recommended the abandonment of low-yielding sloping farmland (>15°) prone to soil degradation by erosion, to allow recovery through natural vegetative regeneration. The effect of this policy on soil nitrogen (N) cycling, as fertilization applications are also withdrawn after abandonment, is poorly understood. A space-for-time approach was applied to investigate the responses of nitrogen functional genes (NFGs) in soil profiles (surface to bedrock) associated with progressive vegetative recovery (sloping farmland > recently abandoned sloping farmland > secondary forest > primary forest) at the Puding Karst Critical Zone Observatory in Guizhou province, southwest China. Coincident soil chemical properties (dissolved organic carbon (DOC), nitrate (NO3--N), ammonium (NH4+-N), available inorganic phosphorus (AP), soil organic carbon (SOC), total nitrogen (TN) and total phosphorus (TP)) were also quantified. We found that the absolute abundance of NFGs significantly varied according to the phase of vegetation recovery, and that concentrations of AP and NO3--N were the best explanatory variables. The external N from fertilizer application promoted the absolute abundances of ammonia-oxidizing archaea (AOA) and ammonia-oxidizing bacteria (AOB) in sloping farmland. The relative abundances of chiA (associated with decomposition) increased with soil depth across all vegetation recovery phases. The relative abundances of chiA and nifH (associated with N fixation) accounted for the largest proportion (58–72%) of the measured NFGs, indicating that active N-acquisition increased along the vegetation recovery gradient. The ratios of (chiA + nifH)/(AOA + AOB) and the sums of (nirK + nirS) were larger in the forest soil than those of sloping farmland and abandoned sloping farmland, implying a greater capacity for N storage potential, though accompanied by increased gas N emission potential, in the karst forest ecosystems. Our results provide a new and comprehensive understanding of soil N cycling potentials at the microscale in degraded and recovering karst ecosystems.
Abstract.
Evans CD, Peacock M, Green SM, Holden J, Chapman PJ, Lebron I, Callaghan N, Grayson R, Baird AJ (2018). The impact of ditch blocking on fluvial carbon export from a UK blanket bog.
Hydrological Processes,
32(13), 2141-2154.
Abstract:
The impact of ditch blocking on fluvial carbon export from a UK blanket bog
We investigated the effects of ditch blocking on fluvial carbon concentrations and fluxes at a 5-year, replicated, control-intervention field experiment on a blanket peatland in North Wales, UK. The site was hydrologically instrumented, and run-off via open and blocked ditches was analysed for dissolved organic carbon (DOC), particulate organic carbon, dissolved carbon dioxide, and dissolved methane. DOC was also analysed in peat porewater and overland flow. The hillslope experiment was embedded within a paired control-intervention catchment study, with 3 years of preblocking and 6 years of postblocking data. Results from the hillslope showed large reductions in discharge via blocked ditches, with water partly redirected into hillslope surface and subsurface flows, and partly into remaining open ditches. We observed no impacts of ditch blocking on DOC, particulate organic carbon, dissolved carbon dioxide or methane in ditch waters, DOC in porewaters or overland flow, or stream water DOC at the paired catchment scale. Similar DOC concentrations in ditch water, overland flow, and porewater suggest that diverting flow from the ditch network to surface or subsurface flow had a limited impact on concentrations or fluxes of DOC entering the stream network. The subdued response of fluvial carbon to ditch blocking in our study may be attributable to the relatively low susceptibility of blanket peatlands to drainage, or to physical alterations of the peat since drainage. We conclude that ditch blocking cannot be always be expected to deliver reductions in fluvial carbon loss, or improvements in the quality of drinking water supplies.
Abstract.
2017
Green SM, Baird AJ, Holden J, Reed D, Birch K, Jones P (2017). An experimental study on the response of blanket bog vegetation and water tables to ditch blocking.
Wetlands Ecology and Management,
25(6), 703-716.
Abstract:
An experimental study on the response of blanket bog vegetation and water tables to ditch blocking
We studied the effect of ditch blocking on vegetation composition and water-table depths in a blanket peatland. Measurements were made for a period of four years (water tables) and five years (vegetation) in the inter-ditch areas of three experimental treatments: (i) open ditches, (ii) ditches blocked with closely-spaced dams and (iii) ditches partially infilled with peat and blocked with dams. It is often assumed that ditch blocking will lead to an increase in the abundance of Sphagnum and, potentially, a reduction in the abundance of sedges, particularly the cotton grasses. However, our data show no treatment effects on the abundance of either group. We did find an effect of time, with the abundance of both sedges and Sphagnum spp. varying significantly between some years. For the sedges there was no systematic change over time, while for the Sphagnum spp. abundance tended to increase through the study period. This systematic change was not related to a measure of the vigour of the sedges, although vigour was lower towards the end of the study compared to the beginning. Our vegetation data are consistent with our water-table data. As with plant type abundance, we did not find any statistically significant differences in water-table depths between treatments, both for annual averages and summer averages. We comment on why ditch blocking does not seem to have affected water tables and vegetation composition at our study site.
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Quine T, Guo D, Green SM, Tu C, Hartley I, Zhang X, Dungait J, Wen X, Song Z, Liu H, et al (2017). Ecosystem service delivery in Karst landscapes: anthropogenic perturbation and recovery.
Acta Geochimica,
36(3), 416-420.
Abstract:
Ecosystem service delivery in Karst landscapes: anthropogenic perturbation and recovery
Covering extensive parts of China, Karst landscapes are exceptional because rapid and intensive land use change has caused severe ecosystem degradation within only the last 50 years. The twentieth century intensification in food production through agriculture has led to a rapid deterioration of soil quality, evidenced in reduced crop production and rapid loss of soil. In many areas, a tipping point appears to have been passed as basement rock is exposed and ‘rocky desertification’ dominates. Through the establishment of the “Soil processes and ecological services in the karst critical zone of SW China” (SPECTRA) Critical Zone Observatory (CZO) we will endevaour to understand the fundmental processes involved in soil production and erosion, and investigate the integrated geophysical-geochemical-ecological responses of the CZ to perturbations. The CZ spans a gradient from undisturbed natural vegetation through human perturbed landscapes. We seek to understand the importance of heterogeneity in surface and below-ground morphology and flow pathways in determining the spatial distribution of key stocks (soil, C, vegetation, etc.) and their control on ecosystem service delivery. We will assess the extent to which the highly heterogeneous critical zone resources can be restored to enable sustainable delivery of ecosystem services. This paper presents the CZO design and initial assessment of soil and soil organic carbon stocks and evidence for their stability based on caesium-137 (137Cs) data.
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Song X, Gao Y, Green SM, Dungait JAJ, Peng T, Quine TA, Xiong B, Wen X, He N (2017). Nitrogen loss from karst area in China in recent 50 years: An in-situ simulated rainfall experiment's assessment.
Ecology and Evolution,
7(23), 10131-10142.
Abstract:
Nitrogen loss from karst area in China in recent 50 years: An in-situ simulated rainfall experiment's assessment
Karst topography covers more than 1/3 of the People's Republic of China in area. The porous, fissured, and soluble nature of the underlying karst bedrock (primarily dolomite and limestone) leads to the formation of underground drainage systems. Karst conduit networks dominate this system, and rainfall takes a crucial role on water cycle at China karst area. Nitrogen loss from the karst system is of particular concern, with regard to nutrient use efficiency as well as water quality, as much of the karst system, including steeply sloping terrain, is used for intensive agriculture. We use simulated rainfall experiments to determine the relationship between rainfall and nitrogen loss at typical karst slope land and then estimate nitrogen loss from the karst soil. The results show that both surface runoff and subsurface runoff have a significant linear correlation with rainfall at all studied sites. Subsurface runoff is larger than surface runoff at two karst sites, while the opposite is true at the non-karst site. Exponential function satisfactorily described the correlation between rainfall and nitrogen concentrations in runoff. Nitrates accounted for 60%–95% of the dissolved nitrogen loss (DN, an index of N-loss in this research). The estimated annual N-loss load varies between 1.05 and 1.67 Tg N/year in the whole karst regions of China from 1961 to 2014. Approximately, 90% of the N-loss load occurred during the wet season, and 90% of that passed through the subsurface. Understanding the processes and estimating N-loss is highly valuable in determining long-term soil security and sustainability in karst regions.
Abstract.
Holden J, Green SM, Baird AJ, Grayson RP, Dooling GP, Chapman PJ, Evans CD, Peacock M, Swindles G (2017). The impact of ditch blocking on the hydrological functioning of blanket peatlands.
Hydrological Processes,
31(3), 525-539.
Abstract:
The impact of ditch blocking on the hydrological functioning of blanket peatlands
Ditch blocking in blanket peatlands is common as part of peatland restoration. The effects of ditch blocking on flow regimes and nearby water tables were examined in a field trial. After an initial 6-month monitoring period, eight ditches had peat dams installed 10 m apart along their entire length (dammed), four of these ditches were also partially infilled through bank reprofiling (reprofiled). Four ditches were left open with no dams or reprofiling (open). These 12 ditches and the surrounding peat were monitored for 4 more years. An initial five-fold reduction in discharge occurred in the dammed and the reprofiled ditches with the displaced water being diverted to overland flow and pathways away from the ditches. However, there was a gradual change over time in ditch flow regime in subsequent years, with the overall volume of water leaving the dammed and the reprofiled ditches increasing per unit of rainfall to around twice that which occurred in the first year after blocking. Hence, monitoring for greater than one year is important for understanding hydrological impacts of peatland restoration. Overland flow and flow in the upper ~4 cm of peat was common and occurred in the inter-ditch areas for over half of the time after ditch blocking. There was strong evidence that topographic boundaries of small ditch catchments, despite being defined using a high-resolution Light Detection and Ranging-based terrain model, were not always equivalent to actual catchment areas. Hence, caution is needed when upscaling area-based fluxes, such as aquatic carbon fluxes, from smaller scale studies including those using ditches and small streams. The effect of ditch blocking on local water tables was spatially highly variable but small overall (time-weighted mean effect
Abstract.
Moore OW, Buss HL, Green SM, Liu M, Song Z (2017). The importance of non-carbonate mineral weathering as a soil formation mechanism within a karst weathering profile in the SPECTRA Critical Zone Observatory, Guizhou Province, China.
Acta Geochimica,
36(3), 566-571.
Abstract:
The importance of non-carbonate mineral weathering as a soil formation mechanism within a karst weathering profile in the SPECTRA Critical Zone Observatory, Guizhou Province, China
Soil degradation, including rocky desertification, of the karst regions in China is severe. Karst landscapes are especially sensitive to soil degradation as carbonate rocks are nutrient-poor and easily eroded. Understanding the balance between soil formation and soil erosion is critical for long-term soil sustainability, yet little is known about the initial soil forming processes on karst terrain. Herein we examine the initial weathering processes of several types of carbonate bedrock containing varying amounts of non-carbonate minerals in the SPECTRA Critical Zone Observatory, Guizhou Province, Southwest China. We compared the weathering mechanisms of the bedrock to the mass transfer of mineral nutrients in a soil profile developed on these rocks and found that soil formation and nutrient contents are strongly dependent upon the weathering of interbedded layers of more silicate-rich bedrock (marls). Atmospheric inputs from dust were also detected.
Abstract.
Green SM, Page S (2017). Tropical peatlands: current plight and the need for responsible management.
Geology Today,
33(5), 174-179.
Abstract:
Tropical peatlands: current plight and the need for responsible management
Peatlands are important carbon stores, but when drained (e.g. for agriculture), this carbon is released to the atmosphere as carbon dioxide (CO2, a greenhouse gas). Globally, at least 15% of peatlands have been drained, mostly in Europe and South-east Asia, and are responsible for 5% of human-derived CO2 emissions. Peatlands have been exploited for generations, but not without local to global consequences, particularly in South-East Asia. However, recognition of the continuous environmental toll caused by peatland exploitation is leading to a need to change attitudes and practices, in order to propel a move towards a more balanced and responsible use of peat in both northern and tropical peatlands.
Abstract.
Green SM, Baird AJ (2017). Using 'snapshot' measurements of CH4 fluxes from an ombrotrophic peatland to estimate annual budgets: interpolation versus modelling.
MIRES AND PEAT,
19 Author URL.
2016
Swindles GT, Green SM, Brown L, Holden J, Raby CL, Turner TE, Smart R, Peacock M, Baird AJ (2016). Evaluating the use of dominant microbial consumers (testate amoebae) as indicators of blanket peatland restoration.
Ecological Indicators,
69, 318-330.
Abstract:
Evaluating the use of dominant microbial consumers (testate amoebae) as indicators of blanket peatland restoration
Peatlands represent globally-important ecosystems and carbon stores. However, large areas of peatland have been drained for agriculture, or peat has been harvested for use as fuel or in horticulture. Increasingly, these landscapes are being restored through ditch blocking and rewetting primarily to improve biodiversity and promote peat accumulation. To date we have little knowledge of how these interventions influence the microbial communities in peatlands. We compared the responses of dominant microbial consumers (testate amoebae) to drainage ditch restoration relative to unblocked ditches in a UK upland blanket peatland (Migneint, North Wales). Two techniques were used for restoration: (i) dammed ditches with re-profiling; and (ii) dammed ditches with pools of open water behind each dam. Testate communities in the inter-ditch areas changed markedly over time and between treatments illustrating the potential of this group of organisms as indicators of blanket peatland restoration status. However, the responses of testate amoebae to peat rewetting associated with restoration were partially obscured by inter-annual variability in weather conditions through the course of the experiment. Although there was considerable variability in the response of testate amoebae communities to peatland drain blocking, there were clearly more pronounced changes in samples from the dammed and reprofiled treatments including an increase in diversity, and the appearance of unambiguous wet-indicator species in relatively high abundances (including Amphitrema stenostoma, Archerella flavum, Arcella discoides type, Difflugia bacillifera and Difflugia bacillarium). This reflects a shift towards overall wetter conditions across the site and the creation of new habitats. However, water-table was not a significant control on testate amoebae in this case, suggesting a poor relationship between water table and surface moisture in this sloping blanket peatland. Our findings highlight the potential of testate amoebae as bioindicators of peatland restoration success; however, there is a need for caution as mechanisms driving change in the microbial communities may be more complex than first assumed. Several factors need to be taken into account when implementing biomonitoring studies in peatlands including: (i) the natural variability of the peatland ecosystem under changing weather conditions; (ii) any disturbance connected with the restoration procedures; and (iii) the timescales over which the ecosystem responds to the management intervention. Our results also suggest an indicator species approach based on population dynamics may be more appropriate for biomonitoring peatland restoration than examining changes at the community level.
Abstract.
2014
Green SM, Baird AJ, Boardman CP, Gauci V (2014). A mesocosm study of the effect of restoration on methane (CH<inf>4</inf>) emissions from blanket peat.
Wetlands Ecology and Management,
22(5), 523-537.
Abstract:
A mesocosm study of the effect of restoration on methane (CH4) emissions from blanket peat
In a mesocosm study, we investigated the effect of different restoration methods on methane (CH4) emissions from, and the global warming potential (GWP) of, blanket peat. The controlled laboratory study involved two distinct components: Experiment 1 focused on greenhouse gas exchanges from blocked drains (grips) and evaluated the effects of restoration method, water-level dynamics and climate on CH4 emissions and GWP. Experiment 2 assessed the role of plant functional type (PFT) on CH4 emissions from restored peat outside of the grip. A nine month meteorological simulation (April- December) was completed, testing five hypotheses across the two experiments. We found that the method of grip blocking/damming does make a difference with respect to CH4 emissions and GWP. of the methods considered, damming with no infill between the dams is preferred to either of the methods involving infilling (heather bale and re-profiling). GWP of all within-grip restoration outcomes was positive (i.e. indicating a net warming effect), and was not influenced by climate or water-level regime. PFT influences CH4 emissions but not GWP in restored blanket bog. When considering radiative forcing, this finding suggests that it does not matter which PFT dominates a restored area. It is noted that the laboratory findings are, in some senses, preliminary because the experiments consider only a relatively short period immediately after restoration.
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2013
Green SM (2013). Ebullition of methane from rice paddies: the importance of furthering understanding. Plant and Soil, 370(1-2), 31-34.
Green SM, Baird AJ (2013). The importance of episodic ebullition methane losses from three peatland microhabitats: a controlled-environment study.
European Journal of Soil Science,
64(1), 27-36.
Abstract:
The importance of episodic ebullition methane losses from three peatland microhabitats: a controlled-environment study
Ebullition and episodic ebullition in particular, may be an important pathway for methane (CH4) losses from northern peatlands. We quantified the importance of episodic ebullition using controlled environment laboratory incubations of samples of near-surface bog peat, focusing on how ebullition can be measured effectively and assessing the variation in CH4 losses between microhabitats and seasons. The peat samples were collected from hollow and lawn microhabitats at two raised bogs: Longbridgemuir, southwest Scotland, and Cors Fochno, west Wales. We found that CH4 fluxes excluding episodic ebullition differed between peatland microhabitats but not between summer and early autumn conditions. Conversely, episodic ebullition did not differ between microhabitat types but virtually stopped after the onset of early autumn conditions. Most strikingly, episodic ebullition was less than 3.3% of total CH4 fluxes, and was therefore an insignificant mechanism of CH4 loss from our peat samples. © 2013 the Authors. Journal compilation © 2013 British Society of Soil Science.
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2012
Green SM, Baird AJ (2012). A mesocosm study of the role of the sedge Eriophorum angustifolium in the efflux of methane-including that due to episodic ebullition-from peatlands.
Plant and Soil,
351(1-2), 207-218.
Abstract:
A mesocosm study of the role of the sedge Eriophorum angustifolium in the efflux of methane-including that due to episodic ebullition-from peatlands
Background & Aim: Vascular plants may reduce episodic ebullition losses of methane (CH 4) from peatlands. They transport CH 4 to the atmosphere, which may lead to a reduction in pore-water [CH 4], bubble formation and release. This effect may be compounded by rhizospheric oxidation and associated methanotrophy. However, any reduction in pore-water [CH 4] may be countered by root exudation (substrate for methanogens). The aim of this study was to determine how the presence of sedges affects CH 4 emissions from peatlands. Methods: Five pairs of peat cores were collected from a raised bog. One of each pair contained Sphagnum cuspidatum and Eriophorum angustifolium ('sedge' cores); the other was dominated by S. cuspidatum ('no-sedge'). From these the total CH 4 efflux-including that due to episodic ebullition-were measured. A partial-shading treatment helped isolate the potential effect of root exudation. Results: Sedge samples had significantly higher CH 4 fluxes than no-sedge samples, but episodic-ebullition fluxes were not significantly different. Between full-light and partially-shaded conditions, there was a significant increase in the difference in CH 4 fluxes between the sedge and no-sedge cores. Conclusion: the higher rates of CH 4 flux from the sedge cores cannot be explained simply by higher rates of CH 4 production due to rapid utilisation of exudates. © 2011 Springer Science+Business Media B.V.
Abstract.
2011
Kettridge N, Binley A, Green SM, Baird AJ (2011). Ebullition events monitored from northern peatlands using electrical imaging.
JOURNAL OF GEOPHYSICAL RESEARCH-BIOGEOSCIENCES,
116 Author URL.
2010
Baird AJ, Stamp I, Heppell CM, Green SM (2010). CH4 flux from peatlands: a new measurement method.
ECOHYDROLOGY,
3(3), 360-367.
Author URL.
2009
Green SM, Machin R, Cresser MS (2009). Does road salting induce or ameliorate DOC mobilisation from roadside soils to surface waters in the long term?.
Environ Monit Assess,
153(1-4), 435-448.
Abstract:
Does road salting induce or ameliorate DOC mobilisation from roadside soils to surface waters in the long term?
Soils down slope of roads have been affected over decades by road salting in the UK uplands. Salt additions to fresh soil facilitate dispersal of organic matter so there is a potential risk of release of DON and DOC to nearby rivers where these run parallel to roads. Over time, however, salting enhances soil pH of naturally acid soils, and thus organic matter degradation through to CO2, thereby, lowering soil organic matter content. In addition any relatively labile organic matter may have already been dispersed. Thus, it is hypothesised that enhanced DOC mobilisation should only be a potential problem if soils not previously exposed to salt become heavily exposed in the future. This paper combines data from field observations and laboratory simulations to elucidate mechanisms controlling organic matter mobilisation processes to determine what controls spatial and temporal trends in DOC concentrations in soil solutions down slope of roads. Organic matter solubilisation is dependent on the degree of road salt exposure soils have had. The laboratory experiment provided evidence that there are two competing effects upon which solubilisation is dependent (a) pH suppression and (b) sodium dispersion. Other organic matter solubility models, if correct, link quite well with the authors "when it's gone, it's gone" hypothesis.
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2008
Green S, Cresser M (2008). Are calcareous soils in uplands less prone to damage from road salting than acidic soils?.
Chemistry and Ecology,
24(1), 1-13.
Abstract:
Are calcareous soils in uplands less prone to damage from road salting than acidic soils?
Previous studies of upland roadside soils in Cumbria, that would normally be naturally acidic, have highlighted that (a) runoff from roads subjected to long-term road salting can dramatically raise soil pH down slope in upland areas; (b) the soil pH increase dramatically changes N cycling in soils down slope, increasing mineralisation of organic matter, ammonification, ammonium leaching down slope and nitrification and nitrate leaching; (c) the increase in nitrification substantially increases nitrate leaching to down-slope rivers, and this is readily detectable in field studies; and (d) loss of soil organic matter over decades of salting is so great that organic matter is no longer substantially solubilised by high salt concentrations found in soil solution below road drains. This paper tests and supports the hypothesis that such effects are minimal for more calcareous soil ecosystems. It examines the soil and soil solution chemistry on another Cumbrian upland highway, the A686 near Leadgate, Alston. Sodium % of soil CEC values for soil transects affected by spray containing road salt are similar at both the A6 and A686 sites. However, spatial trends in calcium, magnesium, ammonium, and nitrate concentrations as well as pH differ, as a direct result of the higher weathering rate of parent material and possibly also the presence of limestone walls above both spray-affected and control transects at the A686 site.
Abstract.
Green SM, Machin R, Cresser MS (2008). Effect of long-term changes in soil chemistry induced by road salt applications on N-transformations in roadside soils.
Environ Pollut,
152(1), 20-31.
Abstract:
Effect of long-term changes in soil chemistry induced by road salt applications on N-transformations in roadside soils.
Of several impacts of road salting on roadside soils, the potential disruption of the nitrogen cycle has been largely ignored. Therefore the fates of low-level ammonium-N and nitrate-N inputs to roadside soils impacted by salting over an extended period (decades) in the field have been studied. The use of road salts disrupts the proportional contributions of nitrate-N and ammonium-N to the mineral inorganic fraction of roadside soils. It is highly probable that the degree of salt exposure of the soil, in the longer term, controls the rates of key microbial N transformation processes, primarily by increasing soil pH. Additional influxes of ammonium-N to salt-impacted soils are rapidly nitrified therefore and, thereafter, increased leaching of nitrate-N to the local waterways occurs, which has particular relevance to the Water Framework Directive. The results reported are important when assessing the fate of inputs of ammonia to soils from atmospheric pollution.
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Green SM, Machin R, Cresser MS (2008). Long-term road salting effects on dispersion of organic matter from roadside soils into drainage water.
CHEMISTRY AND ECOLOGY,
24(3), 221-231.
Author URL.
Green SM, Cresser MS (2008). Nitrogen cycle disruption through the application of de-icing salts on upland highways.
WATER AIR AND SOIL POLLUTION,
188(1-4), 139-153.
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