chapter  5
20 Pages

The carbon budget of upland peat soils

ByFRED WORRALL, MARTIN G. EVANS

Within the terrestrial biosphere the northern peatlands are the most important carbon store. Gorham (1991) has estimated that 20-30 per cent of the global terrestrial carbon is held in 3 per cent of its land area, i.e. in northern peatlands, storing 450 Gtonnes Carbon (C). Over the Holocene these peatlands have accumulated carbon at an average rate of 0.96 Mtonnes C/yr, making this ecosystem not only a substantial store but also a large potential sink of atmospheric carbon. However, with climate warming, increase drought frequency, and changes in rainfall there is the risk that this important store could be transformed from a net sink to a net source of atmospheric carbon. Climatically driven causes of enhanced carbon loss could be extenuated by other factors, including changes in atmospheric deposition and land management.