MODELING THE EFFECT OF SHELTERBELTS ON MAIZE PRODUCTIVITY UNDER CLIMATE-CHANGE - AN APPLICATION OF THE EPIC MODEL

The potential of shelterbelts to ameliorate climate change induced cro p stress, particularly in semi-arid regions such as the North American Great Plains, is examined. Specifically, the microclimate effects of shelterbelts, synthesized from empirical studies in the literature, ar e inserted into the Erosion-Productivity Impact Calculator (EPIC) crop model to simulate the response of dryland maize to shelter at The Uni versity of Nebraska Agricultural Research and Development Center (ARDC ) near Mead, Nebraska. Though lack of extensive observed maize yield d ata precluded rigorous validation, the shelterbelt version of EPIC and a version simulating an unsheltered control were tested with 2 years of observed maize yield data from ARDC. EPIC underpredicted the observ ed ratio of shelter to open field maize yields as expected because not all benefits of shelter to crops can be incorporated into EPIC. Howev er, the two versions correctly simulated the magnitude of difference i n the shelterbelt to open field ratios between the 2 years. The two EP IC versions were then subjected to prescribed increments to temperatur e, and increments/decrements to precipitation and windspeed to examine differences in crop productivity between the two EPIC versions. The r esults show that simulated shelter increases dryland maize yields abov e corresponding unsheltered yields for almost all levels of climate ch ange. The model results suggest that shelterbelts provide a night-time cooling that partially compensates the tendency of warming to shorten the growing season. They also suggest that evapotranspiration is redu ced in shelter, thus reducing crop moisture stress. The positive effec t of shelter on dryland maize at all levels of temperature increase is greatest for the most severe changes: maximum precipitation deficienc y and greatest increase in windspeed. Despite methodological limitatio ns, the findings suggest that shelterbelts may afford important protec tion from climate warming.