Diverging responses of terrestrial ecosystems to water stress after disturbances

Abstract

Terrestrial ecosystems are major carbon (C) pools, sequestering ~20% of anthropogenic C emissions. However, increasing frequency and intensity of climate-sensitive disturbances (for example, drought and wildfire) threaten long-term C uptake. Although direct effects of disturbances are well-documented, indirect effects remain unknown. Here we quantify changes in the sensitivity of terrestrial gross primary production to water stress before and after severe droughts and fires. We find divergent changes across the globe, where dry regions have increased sensitivity, while wet regions have decreased sensitivity. Water availability, solar radiation, nutrient availability and biodiversity are the main drivers mediating these changes. Sensitivity takes ~4–5 years to recover after disturbances, but the increasing frequency of disturbances threatens this recovery. Our results reveal strong cross-system discrepancies in ecosystem responses to disturbances, highlighting the vulnerability of dryland ecosystems in future climates. Climate-sensitive disturbances, such as droughts and wildfires, impact terrestrial carbon uptake. Here the sensitivity of ecosystem productivity to disturbance is found to diverge between regions, with dryland ecosystems becoming particularly vulnerable under a warming climate.