植被对土壤湿度与饱和水汽压亏缺响应的阈值量化OA

This study explores the spatial distribution of flash drought characteristics from multi-source soil data,and quantifies the thresholds of soil moisture and vapor pressure deficit that lead to a decrease in solar-induced chlorophyll fluorescence under flash drought conditions,using a two-dimensional copula method.We also examines the thresholds'spatial heterogeneity in different aridity zones and different vegetation types across China.The results show that in the period of 2001-2020,the northern region experienced flash droughts less than 8 times,lasting over 10 pentads,with intensities mostly at Levels 3-4.In contrast,the southern region experienced more than 8 times,lasting about 6-10 pentads,with intensities mostly at Levels 1-2.For soil moisture-dominated region,the soil moisture thresholds for SIF≤SIF40%are roughly 0.39 m3m-3,0.35 m3m-3,0.25 m3m-3,and 0.06 in the humid,sub-humid,semi-arid,and arid zones,respectively,and 0.38 m3m-3,0.35 m3m-3,and 0.28 m3m-3 for forests,croplands,and grasslands,respectively.In vapor pressure deficit-dominated regions,the thresholds are around 7 hPa,4 hPa,and 2.5 hPa in arid,humid and sub-humid,and semi-arid zones,respectively,and 5 hPa,4 hPa,and 3 hPa for croplands,forests,and grasslands,respectively.