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Drought can have major impacts on rangeland productivity and remains highly unpredictable.  The objective of this study was to determine the drought resistance and resilience of introduced cool-season pasture vs. native tallgrass pasture.  Two sites near Brookings, SD were used for the study: an introduced cool-season grass site dominated by Bromus inermis and Poa pratensis and a native site with cool- and warm-season grasses, and some forbs.  Three automated rainout shelters at each site simulated drought conditions by intercepting rainfall.  In 2013, 2 replicates of supplemental watering treatments were applied under each shelter at 50, 75, 100, and 125% of average growing season precipitation to 1-m2 plots. Outside the shelters, optimal and ambient precipitation treatments were applied to 1-m2 plots.  In 2014, the same treatments will be conducted to determine drought resistance, however half of the 50, 75, and 125% plots will return to 100% or average precipitation to study drought resilience.  Water was applied on a weekly schedule based on the 30-year average precipitation after being subtracted from the rainfall not excluded by the shelters.  After the first hard frost, biomass will be clipped by species, dried at 60°C, weighed, and combined into functional groups. Statistical Analysis will include two-way ANOVAs and mean separations to determine significant differences between treatments and sites.  First year data will be available at the end of the 2013-growing season.  This study will provide information to land managers and producers about the biomass production of introduced cool-season pastures vs. native prairie during drought and after drought.  We expect that native prairie will be more resistant to drought than introduced cool-season pasture, but may not be more resilient when normal or above-normal precipitation returns.