Data and code for "Greater drought sensitivity of Eurasian than North American grasslands"

Extreme droughts generally decrease productivity in grassland ecosystems with negative consequences for nature’s contribution to people. The extent towhich this negative effect varies among grassland types and over time in response to multi-year extreme drought remains unknown. Using a coordinated distributed experiment that simulated four-years of growing-season drought (~66% rainfall reduction), we compared drought sensitivity within and among six grasslands spanning broad precipitation gradients in each of Eurasia and North America - two of the Northern Hemisphere’s largest grass-dominated regions. Aboveground plant production declined substantially with drought in the Eurasian grasslands and effects accumulated over time, while the declines were less severe and more muted over time in the North American grasslands. Drought effects on species richness shifted from positive to negative in Eurasia, but from negative to positive in North America over time. The differing responses of plant production in these grasslands were accompanied by less common (subordinate) plant species declining in Eurasian grasslands but increasing in North American grasslands. Our findings demonstrate the high production sensitivity of Eurasian compared to North American grasslands to extreme drought (43.6% vs. 25.2% reduction), and the key role of subordinate species in determining impacts of extreme drought on grassland productivity.