SENSITIVITY OF 4 WHEAT SIMULATION-MODELS TO CLIMATE-CHANGE

Crop simulation models may be valuable in anticipating crop production under a changed climate. We compared four computer simulation models of wheat, crop estimation through resources and environment synthesis (CERES), erosion productivity impact calculator (EPIC), Stewart and Si nclair, for evaluating the impact of climate change on dryland spring wheat yield for continuous rotation in southern Alberta. To a varying extent, the four models showed decreases in dryland spring wheat yield s due to high temperature and low precipitation. All the models except Stewart had similar sensitivity to low precipitation; however, they s howed differences to high-moisture conditions. Within the range consid ered, the Sinclair model was the most sensitive to temperature, follow ed by CERES and Stewart. Only EPIC indicated optimum temperature and p recipitation levels, while CERES had the most pronounced precipitation optimum. Although the CERES, Stewart and Sinclair models have differe nt phenology submodels, they predicted similar phenological response t o a doubled CO2 climate scenario generated from the Canadian Climate C enter General Circulation Model for Lethbridge, AB. Growing seasons sh ortened by 19 d were predicted using CERES and 18 d by using the Sincl air and Stewart models. The CERES, Stewart and Sinclair models were mo dified to include the effect of CO2 on radiation-use-efficiency. With current atmospheric CO2 concentration in the future climate scenario, the EPIC and Stewart models predicted significant (25%) and non-signif icant (3%) yield increases for dryland wheat and Sinclair and CERES pr edicted yield losses. Higher CO2 levels may compensate for the effect of global warming; doubling CO2 from present levels in a warmer climat e scenario resulted in yield increase predictions at different amplitu des using EPIC, Stewart and CERES and a slight yield decrease with Sin clair.