Characteristics of Drought Events and Their Impact on Vegetation Dynamics in the Arid Region of Northwest China

The arid region of Northwest China (ARNC) is responsive to global climate change, and drought events have occurred frequently in recent decades. However, studies about the effect of meteorological and drought stress on vegetation change in the ARNC are still insufficient. In this study, we analyzed the spatiotemporal trends of meteorological factors (temperature, TMP; precipitation, PRE; standardized precipitation evapotranspiration index, SPEI), drought stress factors (vapor pressure deficit, VPD; soil moisture, SM), and vegetation (normalized difference vegetation index, NDVI) during 1982–2021. We also investigated the characteristics of drought events by the run theory, including drought times, drought duration, drought severity, and drought intensity. The impacts of meteorological and drought stress factors on the vegetation were explored using Pearson correlation analysis and the structural equation model (SEM). We found that the annual and growing season TMP, PRE, VPD, SM, and NDVI showed an increasing trend in the ARNC during 1982–2021. In contrast, SPEI exhibited a decreasing trend in the annual and growing season. In addition, the characteristics of the drought events varied significantly in the ARNC. The drought events primarily occurred in the Tarim River Basin, Turpan-Hami Basin, and the Hexi Corridor. The Pearson correlation analysis and SEM results consistently demonstrated that TMP and SM exerted greater impacts on vegetation growth than PRE, VPD, and SPEI. The factors that determine vegetation change were TMP and PRE. Exploration of meteorological and drought stress factors that influence vegetation change is essential for comprehending the influence of dominant factors on vegetation change.