CLIMATE CHANGE, WINTER-WHEAT YIELD AND SOIL-EROSION ON THE ENGLISH SOUTH DOWNS

The EPIC (Erosion-Productivity Impact Calculator) model is used to assess the impact of increased atmospheric CO2 levels upon winter wheat yield and soil erosion on the UK South Downs. This impact includes both the direct effects of increased CO2 concentration upon the crop's metabolic processes, and the indirect effects of CO2-induced climate change upon crop growth. Yield increases are predicted under the majority of climatic scenarios used in the simulations; these increases are considerable when the direct effects of increased CO2 levels are considered. However, they are unlikely to be realised in practice due to increased pest competition. An increase in erosion is predicted for the wetter scenarios. The EPIC model appears generally suited to this kind of impact analysis, although changes are required in some areas.