CARBON STORAGE IN FOREST SOILS

The amounts of carbon stored in soils and vegetation in Britain, and t he potential of forestry to influence, whether soils act as sinks or s ources, are discussed. Soils are estimated to contain c.22 X 10(9) t c arbon, while the amount in vegetation including forests is only 115 X 10(6) t. Some 86 per cent of the soil carbon is present in pears and p eaty-surfaced soils, mainly in north-west Britain. Soil carbon content is strongly related to climate and altitude. Conversion of lowland cu ltivated land to forest can result in carbon accumulation in soils, as it can following the planting of some uplands, but quantities appear to be small in relation to the amounts carbon released to the atmosphe re through fossil fuel use. Forest felling may result in decreases in soil carbon store, due to soil disturbance and changes in microclimati c conditions, but several decades after reafforestation the carbon sto re may recover to near original levels. Shortening forest rotations ma y result in long-term declines in soil carbon store. The main concern is the potential for forestry to convert peats, which contain amounts of carbon equivalent to 100 years' fossil fuel use at 1988 levels and which are normally slow sinks for atmospheric carbon, into carbon sour ces returning it to the atmosphere. The possible impacts of forestry a nd global warming on rates of carbon loss from upland soils including peats are discussed.