Assessing vegetation resilience and vulnerability to drought events in Central Asia

Extreme drought events in Central Asia are becoming increasingly frequent, causing further harm to the vegetation in this region. It is essential to comprehend how vegetation continually responds to extreme drought events, focusing on both resistance and recovery aspects. To address this, based on the run theory, the study quantified drought characteristics for drought events affecting vegetation. Then, vegetation resistance and resilience to drought events were assessed by adopting a 'resistance–resilience' framework. Further analysis evaluated vegetation vulnerability to drought events by considering both vegetation resistance and resilience. The impact of different drought features on vegetation vulnerability to drought events was quantified using the boosted regression tree (BRT) model. The results showed that rainfed croplands in Northern Kazakhstan exhibited low resistance to drought events, while sparse vegetation in southern Central Asia displayed higher resistance compared to the other land covers. Moreover, natural vegetation demonstrated a longer resistance time compared to croplands. However, the opposite pattern was observed for vegetation resilience, with croplands and sparse vegetation showing high and low resilience, respectively. Sparse vegetation had a longer recovery time compared to croplands. Notably, the Amu Darya delta exhibited vegetation with low resistance and resilience. Furthermore, the study revealed that vegetation resilience in arid areas was more sensitive to dryness compared to humid areas. Regarding vegetation vulnerability to drought events, vegetation in southern region experienced low vulnerability. In contrast, croplands and grasslands around the Aral Sea showed high vulnerability. Most vegetation in the semi-arid zone was more susceptible to the negative impacts of drought events, particularly in croplands and grasslands, compared to other climate zones. The BRT model revealed that drought duration was found to be the primary factor influencing vegetation vulnerability to drought events, accounting for approximately 40% of the explanation in the model. The influences of drought duration on vegetation vulnerability intensified from forests (28.17%) to sparse vegetation (55.87%). The number of drought events contributed only approximately 5% of the explanation. With an understanding of vegetation resilience and vulnerability, policymakers and land managers can make informed decisions and implement measures to mitigate the negative effects of drought, protect fragile vegetation, and promote sustainable management practices in Central Asia.