Winter Wheat Yield Responses to Climate Variation in the U.S. Central Great Plains

Abstract. Climate change vulnerability assessments represent an effort to characterize the sensitivity and exposure of a system to climate change and variability, as well as adaptive capacity of the system. Our research objective was to quantify sensitivity of dryland agricultural productivity in the U.S. Central Great Plains to components of climate change. Grain productivity and planted acreage of winter wheat in Kansas were taken as indicators of the spring crop phase of land productivity for the U.S. central Great Plains. A drought index (SPEI_6) and an indicator of the El Nino/Southern Oscillation (NINO_3) were selected as representation of climate variation. Multiple regression models were constructed, relating variation in yield and relative planted acre to variation in climate indicators. Cluster analysis indicated structural differences in the temporal variation of wheat productivity west and east of the 99^th Meridian. Monthly values for SPEI_6 (Feb., Mar., and Apr.) were positively correlated with variation in wheat yield in W Kansas but not E Kansas; corresponding multiple regression relationships had R² = 0.41 and 0.25, respectively. The NINO_3 data, recorded up to 20 months prior to planting period, exhibited forecasting skill for wheat yield variability in W Kansas as well as the region‘s SPEI_6 values for Feb., Mar. and Apr. The differential sensitivity of yield variation to drought indices in semi-arid and sub-humid Kansas support inference of regional differences in sensitivity. The forecasting skill of NINO_3 data indicates opportunity to increase the adaptive capacity of dryland management systems for drought mitigation.