Spatial and temporal trends in agro-climatic limitations to production potentials for grain maize and winter wheat in Switzerland

Climate is a major driver of agricultural production potentials. To make the best use of these potentials, agricultural management should be adjusted to local climatic conditions. As these conditions change over time, understanding climatic limitations and their trends in time and space is essential for the planning of suitable adaptation measures. In this study, we provide a detailed spatio-temporal analysis of climatic yield potentials for grain maize and winter wheat in Switzerland. We find that current climatic suitability for grain maize is mostly limited by sub-optimal temperatures, radiation and water scarcity, while climatic suitability for winter wheat is mostly limited through excess water, insufficient radiation, as well as frost and heat stress. Over the investigated period from 1983 to 2010, few regional trends in climate suitability were identified for the two crops, indicating that grain maize has benefitted slightly from increasing growth temperatures with recent warming (0.5 degrees C/decade), while winter wheat suitability decreased slightly due to suboptimal radiation/temperature ratios with warming. Despite only small trends in climate suitabilities, which are restricted to particular regions, future climatic changes could lead to more pronounced shifts. The tendencies of climate limitations identified in this study are mostly consistent with findings from other studies, and it can thus be anticipated that maize may continue to benefit from increasing temperatures on the short term, but may also be increasingly limited by water scarcity as summer precipitation decreases. For winter wheat, the relevance of heat stress is likely to increase with increasing temperatures. These results may help to support short-term adaptation planning. However, more detailed analyses of climate projections will be necessary to investigate critical transitions and provide more specific information to support long-term climate change adaptation planning (e.g. for irrigation and breeding programmes).