Effects of ecological drought on vegetation in Inland River Basin of Inner Mongolia Plateau

Inland River Basin of Inner Mongolia Plateau(IRB), China. Ecological drought (ED) may trigger irreversible ecosystem disruptions, including shifts in habitat distribution patterns and sharp reductions in species populations within affected environments. This research developed the Standardized Ecological Water Deficit Index (SEWDI), while employing the Carnegie-Ames-Stanford Approach (CASA) model to quantify Net Primary Productivity (NPP) variations in Inland River Basin (IRB). The cumulative and laggged effects of ED on NPP were analyzed using the maximum correlation coefficient method. The NPP loss probability of different ED levels was calculated based on Copula function. The impacts of ED and meteorological factors on NPP were examined through Structural Equation Modeling (SEM). The results reveal that the mean annual NPP exhibited a distinct southeast-to-northwest gradient in spatial distribution. The maximum cumulative correlation between SEWDI and NPP was 87.89 %, mainly in the southern part of IRB. The maximum lagged time correlation showed a positive correlation of 74.65 %, and the average lagged time was 2.60 months. With the increase of ED grade, the probability of NPP loss decreased, and when ED occurred, the high loss probability of NPP less than 0.4 and 0.3 quantile was located in the eastern part of IRB. The total effect of different factors on NPP was SEWDI (0.086), Prec (0.159), Temp (0.282) and Srad (0.077). • Coupling NDVI and evapotranspiration to construct a SEWDI to characterize ecological drought. • The longest cumulative and lagged times were observed in the central and eastern Inland River Basin. • The probability of NPP loss in different ecological droughts was calculated based on Copula function. • The pathways by which meteorological factors affect NPP by controlling ecological drought were explored through SEM.