Extreme drought is increasing in frequency and intensity in many regions globally, with uncertain consequences for the resistance and resilience of ecosystem functions that impact biogeochemical cycling, including primary production. Primary production resistance, the capacity to withstand change during extreme drought, and resilience, the degree to which production recovers, vary among and within ecosystem types, obscuring generalized patterns of ecological stability. Theory and most observations suggest forest production is more resistant but less resilient than grassland production to extreme drought; however, studies of production sensitivity to precipitation indicate that the processes controlling resistance and resilience may be influenced more by mean annual precipitation (MAP) than ecosystem type. Here, we conducted a global meta-analysis to investigate primary production resistance and resilience to extreme drought in 64 forests and grasslands to evaluate whether different ecosystems exhibit shared or divergent responses across a common precipitation continuum. We examined relationships between MAP and resistance and resilience for forests and grasslands using a Bayesian analysis of covariance model.
Results/Conclusions
We found that forests and grasslands exhibit a common pattern of resistance across a continuum of precipitation. Forests are, on average, more resistant than grasslands to extreme drought because they are located in wetter climates, and not because they are inherently more resistant to drought than grasslands. In contrast, forests and grasslands displayed opposite patterns of primary production resilience with rising precipitation. Common mechanisms may determine grassland and forest resistance to extreme drought, whereas life history differences likely underlie divergent resilience patterns. Finally, our analyses suggest that dry grasslands around the world are particularly vulnerable to extreme droughts suggesting these ecosystems should be targeted for conservation efforts.