Differentiating cumulative and lagged effects of drought on vegetation growth over the Mongolian Plateau

Abstract

Drought has a great impact on global terrestrial ecosystems. A large number of studies have shown that the impact of drought on vegetation growth has a lagged and cumulative effect, but it is unclear how much it contributes to different vegetation types. Therefore, based on the standardized precipitation evapotranspiration index (SPEI) base version 2.5 and the Global Inventory Monitoring and Modeling System (GIMMS3g) normalized difference vegetation index (NDVI) datasets, this study aimed to analyze the response process of different vegetation types to the cumulative and lagged effects of drought in the Mongolian Plateau during 1982–2015 using Pearson correlation and the Mann–Kendall mutation method and deeply explore the magnitude of the contribution of drought cumulative and lagged effects on vegetation using the multiple regression method. Our results show that, from 1982 to 2015 as a whole, NDVI showed an insignificant increasing trend, and SPEI had a significant mutation in 1998 and showed an insignificant increasing trend before and after 1998. Before 1998, the cumulative months were shorter (1–3 months) in the central steppe and agricultural vegetation zones, and the lagged months were longer (10–12 months) in the southeastern steppe and northeastern forest zones; after 1998, the cumulative months of NDVI increased (7–12 months) and the lag months decreased (3–8 months) in most vegetation zones. A comparison of the contribution of drought accumulation and lag to NDVI revealed that the main driver of NDVI has shifted from lagged to cumulative effect.