The time required for an ecosystem to recover from severe drought is a key component of ecological resilience. The phenology effects on drought recovery are, however, poorly understood. These effects center on how phenology variations impact biophysical feedback, vegetation growth and, ultimately, recovery itself. Using multiple remotely-sensed datasets, we found that more than half of ecosystems in mid and high latitudinal northern hemisphere failed to recover from extreme droughts within a single growing-season. Earlier spring phenology in the drought year slowed drought recovery when extreme droughts occurred in the mid-growing season. Delayed spring phenology in the subsequent year slowed drought recovery for all vegetation types (with the importance of spring phenology ranging from 46%-58%). The phenology effects on drought recovery were comparable to or larger than other well-known post-drought climatic factors. These results strongly suggest that the interactions between vegetation phenology and drought must be incorporated into earth system models to quantify ecosystem resilience accurately.
We first quantified and compared the spatial pattern in the two trajectories of drought recovery: within a single growing season (Rsgs), or persisting to the subsequent growing-season (i.e., within multiple growing-seasons) (Rmgs)
Our analysis revealed that in ~50% of early-growing-season extreme drought events, NDVI-based vegetation greenness did not fully recover to the pre-drought condition within a single growing-season. This percentage increased to more than 60% and 80% when extreme drought events occurred in the mid- and late-growing-season, respectively.
The analyses identified significant but differentiated phenological effects on drought recovery among different vegetation types and between and Rsgs and Rmgs. For Rsgs spring phenology was found to strongly impact drought recovery. However, both earlier and delayed spring phenology in drought year postponed drought recovery within a single growing-season for all vegetation types. For the Rmgs, a delayed spring phenology in the subsequent year will postpone drought recovery.
