Dr Iain Hartley had led a study that has found carbon stored in Arctic tundra could be released into the atmosphere by new trees growing in the warmer region, exacerbating climate change.

Landscape and ecosystem dynamics

Soil carbon dynamics

Our soil carbon (C) research addresses a wide range of research questions, across contrasting spatial and temporal scales, with topics ranging from environmental change impacts on soil microbes to improving national soil C inventories. Recent highlights include Marie Curie and NERC-funded research that has enhanced 3D modelling of soil organic C distributions at national scales, and in semi-arid deserts, and also research that has demonstrated that soil microbial community adaptations to temperature change, as well as increased plant growth, could promote the release of C from Arctic soils.

One of our main research areas investigates the redistribution of soil and sediment through the landscape and the control that this redistribution exerts on nutrient and C dynamics. Erosion control has been identified as a potential strategy for increasing C sequestration in soils and thus for offsetting fossil fuel emissions. However, the impact of erosion on C storage at the landscape level remains poorly understood. We have led the use of fallout radionuclides (137Cs, 210Pbex) in erosion research and employ a wide range of other field and laboratory-based methodologies in the investigation of erosion rates and in tracing nutrient and C pathways. By incorporating our findings into three-dimensional models, a radically different view of the influence of soil redistribution on carbon sequestration has been developed, indicating that erosion may actually represent a net C sink. Much of our early work centred on mechanised agriculture in temperate environments; however, we are extending the reach of this research. Working with the Chinese Academy of Agricultural Sciences, we are exploring whether pre-restoration, actively eroding, and subsistence fields of the semi-arid loess plateau of China are in steady-state with respect to carbon. In southern Spain, we have investigated recovery of carbon stocks in semi-arid agricultural landscapes following conversion from cropland to extensive pasture. In collaboration with the Indian Council for Agricultural Research and its Central Soil and Water Conservation Research and Training Institute (Dehradun) we are engaged in work to examine perturbation of soil carbon dynamics in sub-tropical, montane, subsistence agricultural landscapes. This work will also address the wider implications of erosion-induced perturbation of C and nutrient dynamics on the delivery of key ecosystem services. Closer to home, we have investigated the impact of land use change, climate change and management practices (e.g. intensive soil drainage for cultivation purposes, tillage and manure application) on the spatial and temporal evolution of soil organic C across large-spatial scales in Northern Europe. Our multidisciplinary approach allowed us to evaluate the relative importance of the different drivers that may have modified soil organic C status since the agricultural revolution (i.e. over +/- the last 60 years). Based on this expertise (and in collaboration with INRA-Orleans, CERFACS-Toulouse and University of Leuven) we are currently conducting spatially refined projections of SOC at the sub-continental scale up to 2100. This represents a powerful tool for policy makers setting-up appropriate measures to combat key environmental issues such as soil fertility decline and climate change.

There is growing concern that rising temperatures could result in the release of C from soils, potentially accelerating the rate of 21st century climate change. We lead research which aims to determine the magnitude and likelihood of any such positive feedback to global warming. Controlled laboratory experiments have been conducted to develop the mechanistic understanding required to predict how rates of decomposition will respond to changes in temperature in the medium to long term. We have investigated whether there is any difference in the temperature sensitivity of the decomposition of labile and recalcitrant pools of soil organic matter, and determined the potential for microbial community adaptation to reduce or enhance the direct effects of warming on decomposition rates. Furthermore, our group has been involved in designing and running manipulative field-studies in diverse ecosystems ranging from Arctic tundra to the Sonoran and Chihuahuan deserts of North America. Our experimental and field-monitoring research also investigates how plant-soil interactions, and links between carbon and nutrient cycling, control the responses of contrasting ecosystems to global change. One recent research highlight emphasised that, due to the stimulation of decomposition rates in soils, increased plant growth in the European Arctic could, counterintuitively, result in a net loss of C. Finally, a growing research area is in permafrost C dynamics, with ongoing NERC and Department of Energy and Climate Change (DECC)-funded work in Canada and Alaska, aiming to determine the rate at which CO2 and CH4 may be released to the atmosphere following climate change-induced thaw. All of our empirical work is strongly linked with process-based modelling to achieve the aim of improving predictions of rates of 21st century change.

News stories:

Expansion of forests in the European Arctic could result in the release of carbon dioxide

Recent funding:

Oct 2010-Oct 2013
NERC Standard Grant: NE/H022333/1, Award: £269,000 to Hartley as PI.  “Thermal acclimation of soil microbial respiration: consequences for global warming-induced carbon losses?”

Aug 2012-July 2015
NERC Standard Grant: NE/K000179/1, Award: £203,376 to Hartley and Charman. “CYCLOPS: Carbon Cycling Linkages of Permafrost Systems”.

May 2013-Sept 2013
Department of Energy and Climate Change: Determining the role of permafrost thaw in controlling rates of methane release from terrestrial high-latitude ecosystems. Total value £193,103.

Key publications:

  1. Brazier, R.E., Turnbull, L. Bol, R. and Wainwright, J. (2013) Carbon loss by water erosion in drylands: implications from a study of vegetation change in the southwest USA. Hydrological Processes. DOI: 10.1002/hyp.9741
  2. Doetterl, S., Stevens, A., Van Oost, K., Quine, T.A. & Van Wesemael, B. (2013). Spatially-explicit regional-scale prediction of soil organic carbon stocks in cropland using environmental variables and mixed model approaches, Geoderma, 204-205, 31-42
  3. Evans, M.G., Quine, T.A. & Kuhn, N. (2013). Geomorphology & Terrestrial Carbon Cycling, Earth Surface Processes and Landforms, 38, 103-105.
  4. De Baets, S., Meersmans, J., Vanacker, V., Quine, T.A., & Van Oost, K. (2012). Spatial variability and change in soil organic carbon stocks in response to recovery following land abandonment and erosion in mountainous drylands, Soil Use and Management, 29, 65-76
  5. Hartley IP et al. (2012) A potential loss of carbon associated with greater plant growth in the European Arctic. Nature Clim. Change 2, 875-879.
  6. Puttock, A.,  Dungait, J.A.J.,  Bol, R., Dixon, E.R., Macleod, C.J.A. and Brazier, R.E. (2012)    Stable carbon isotope analysis of fluvial sediment fluxes over two contrasting C4 -C3    semi-arid vegetation transitions. Rapid Communications in Mass Spectrometry. 26, 1-7. DOI: 10.1002/rcm.6257
  7. Smith P., Ashmore, M., Black, H., Burgess, P., Evans, C., Quine, T.A., Thompson, A., Hicks, K. & Orr, H. (2012). The role of ecosystems and their management in regulating climate, and soil, air and water quality, J Applied Ecology 50, 812–820
  8. Burke EJ et al. inc. Hartley IP (2012) Uncertainties in the global temperature change caused by carbon release from permafrost thawing. Cryosphere 6, 1063–1076.
  9. Meersmans, J., van Wesemael, B., Goidts, E., Van Molle, M. (2011). Spatial analysis of soil organic carbon evolution in Belgian cropands and grasslands, 1960-2006. Global Change Biology, 17, 466-479.
  10. Hartley IP et al. (2010) The response of organic matter mineralisation to nutrient and substrate additions in sub-arctic soils. Soil Biol. Biochem. 42, 92-100.
  11. van Wesemael, B., Paustian K., Meersmans, J., Goidts, E., Barancikova, G., Easter, M. (2010). Agricultural management explains historic changes in regional soil C stocks. Proceedings of the National Academy of Sciences of the United States of America, 107, 14926-14930.
  12. Van Oost K.; Cerdan O.; Quine T. A. (2009). Accelerated sediment fluxes by water and tillage erosion on European agricultural land. Earth Surface Processes and Landforms, 34, 1625-1634.
  13. Meersmans, J., van Wesemael B., De Ridder F., Fallas Dotti M., De Baets S., Van Molle M. (2009). Temporal analysis of organic carbon distribution with depth in agricultural soils in north Belgium. Global Change Biology, 15, 2739-2750.
  14. Hartley IP et al. (2008) Soil microbial respiration in arctic soil does not acclimate to temperature. Ecol. Lett. 11, 1092-1100.
  15. Van Oost, K., J. Six, G. Govers,  T. A. Quine, S. De Gryze. 2008. Soil Erosion: a Carbon Sink or Source: Response to Lal and Pimentel, Science, 319, 1042
  16. Hartley IP, Ineson P (2008) Substrate chemistry and the temperature sensitivity of soil organic matter decomposition. Soil Biol. Biochem. 40, 1567-1574.
  17. Hawkes CV et al. inc. Hartley IP (2008) Soil temperature affects carbon allocation within arbuscular mycorrhizal networks and carbon transport from plant to fungus. Glob. Change Biol. 14, 1181-1190.
  18. Van Oost, K., Quine, T. A., Govers, G., De Gryze, S., Six, J., Harden, J. W., Ritchie, J. C.,  McCarty, G. W., Heckrath, G, Kosmas, C., Giraldez, J. V., da Silva, J. R. Marques, Merckx, R. (2007). The impact of agricultural soil erosion on the global carbon cycle, Science, 318, 626-629