How will global warming affect the soil carbon cycle ?
© 2012 EPFL
The impact of climate change on terrestrial ecosystems is not straightforward: on the one hand, warming can reduce the soil organic carbon pool (SOC) by accelerating decomposition, on the other it can increase plant-derived carbon inputs to soils.
Northern peatlands store approximately 30% of the global SOC, although they cover only 3-5% of the world’s land area. In these ecosystems, although plant litter chemistry and anoxic soil conditions are the major factors enhancing SOC accumulation, temperature and precipitation are also important drivers. The contribution of the two main plant types, vascular plants and sphagnum mosses, to carbon accumulation and nutrient cycling differs notably. Vascular plant litter is much more decomposable than sphagnum litter, so any environmental change favoring vascular plants will reduce the rate of SOC accumulation. In addition, climate change is also expected to affect aboveand below-ground soil microbe interactions, creating potentially serious feedbacks in the global carbon cycle.
L. Bragazza, A. Buttler, A. Siegenthaler, E. Mitchell
(2009). Plant litter decomposition and nutrient release in peatlands. In: Carbon cycling in northern peatlands. Geophysical monograph 184:99-110. edited by: Baird A., Belyea L., Comas X., Reeve R., and Slater L.