Assessment of terrestrial ecosystem sensitivity to climate change in arid, semi-arid, sub-humid, and humid regions using EVI, LAI, and SIF products

Abstract

Arid and humid ecosystems are undergoing significant changes over the past decades due to the warming temperature and frequent occurrence of climate extremes. Quantifying climatic vegetation sensitivity in regions with different climate classifications is crucial for understanding the interaction mechanisms between vegetation and ongoing climate change. However, such knowledge about the spatiotemporal variations of vegetation sensitivity and its climate driving factors in arid and humid regions is still unclear. Based on this consideration, a moving-window-based Vegetation Sensitivity Index (VSI) scheme was applied to Enhanced Vegetation Index (EVI), Leaf Area Index (LAI), and Solar-induced Chlorophyll Fluorescence (GOSIF) data to evaluate the spatiotemporal variations of terrestrial ecosystem in response to climate changes and explore its driving climatic factors from 2003 to 2020. Results indicated that high VSI (>60) was observed for tropical rainforests in humid regions and central Eurasia in semi-arid regions. By contrast, low VSI (<40) was typically observed in arid regions. Spatially, we found VSI exhibited a nonlinear parabolic variation along the gradient of aridity index in the arid and semi-arid regions but generally presented a linear variation with an upward trend in the humid regions. Temporally, VSI showed a significant declining trend over the past two decades but displayed a significantly increasing trend in arid areas. Temperature was the dominant climatic factor to explain the spatial variations of VSI globally, while precipitation mainly dominated the temporal variations of VSI. The dominant climatic factor of VSI varied across different aridity regions as temperature and precipitation were the main climate factor to drive spatiotemporal variations of VSI in humid and arid classifications, respectively. Our results provide unique insights into the vegetation sensitivity in response to ongoing and future climate change in regions with different climate classifications.