Modelling 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 crop 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, are inserted into the Erosion-Productivity Impact Calculator (EPIC) crop model to simulate the response of dryland maize to shelter at The University of Nebraska Agricultural Research and Development Center (ARDC) near Mead, Nebraska. Though lack of extensive observed maize yield data 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 observed ratio of shelter to open field maize yields as expected because not all benefits of shelter to crops can be incorporated into EPIC. However, the two versions correctly simulated the magnitude of difference in the shelterbelt to open field ratios between the 2 years. The two EPIC versions were then subjected to prescribed increments to temperature, and increments/decrements to precipitation and windspeed to examine differences in crop productivity between the two EPIC versions. The results show that simulated shelter increases dryland maize yields above corresponding unsheltered yields for almost all levels of climate change. 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 reduced in shelter, thus reducing crop moisture stress. The positive effect of shelter on dryland maize at all levels of temperature increase is greatest for the most severe changes: maximum precipitation deficiency and greatest increase in windspeed. Despite methodological limitations, the findings suggest that shelterbelts may afford important protection from climate warming.