Compound hot-dry events greatly prolong the recovery time of dryland ecosystems

Abstract

Compound hot-dry events cause more severe impacts on terrestrial ecosystems than dry events, while the differences in recovery time (ΔRT) between hot-dry and dry events and their contributing factors remain unclear. Both remote sensing observations and eddy covariance measurements reveal that hot-dry events prolong the recovery time compared with dry events, and greater prolongation of recovery time in drylands than that in humid regions. Random forest regression model demonstrates that the difference in vapour pressure deficit between hot-dry and dry events, with an importance score of 35%, is the major factor contributing to ΔRT. The severity of stomatal restriction exceeds that of non-stomatal limitation, which restricts the vegetation productivity necessary for the recovery process. These results emphasize the negative effect of vapour pressure deficit on vegetation recovery during hot-dry events and project an extension of drought recovery time considering elevated vapour pressure deficit in a warming world.