澜沧江流域植被生态需水时空演变特征及其驱动因素OACHSSCD

The Lancang River is a vital transnational river in China,whose water resources and ecological stability are highly sensitive to climate change.Vegetation ecological water demand is a key indicator of regional ecosystem health;however,current research focuses mainly on water requirement estimation,with limited exploration of the underlying physiological mechanisms and reliability of these estimates.Based on multi-source remote sensing and meteorological data from 2000 to 2020,this study employed a soil moisture stress-modified Penman-Monteith model to estimate the actual ecological water requirement(ETC)of vegetation in the upper and middle reaches of the Lancang River Basin.The reliability of the model was verified through comparison with existing studies.Random forest analysis was further applied to unravel the driving mechanisms of climatic,soil,and topographic factors on water requirements.The results showed that:(1)Vegetation ecological water demand exhibited a distinct gradient of"forest＞shrubland＞grassland".The annual ETC of evergreen forests(1100-1500 mm)was approximately ten times that of alpine vegetation(120 mm).(2)Significant spatial heterogeneity in ecological water deficit was observed,with water surplus in the northwestern region and pronounced water shortage in the central-eastern areas.Alpine vegetation demonstrated strong adaptability to water availability,while meadows and evergreen broad-leaved forests were prone to experiencing water stress under drought conditions.(3)The dominant factors influencing water demand varied among vegetation types:meadow and alpine vegetation were primarily controlled by precipitation,evergreen coniferous forests and shrublands were sensitive to temperature,and evergreen broad-leaved forests were co-driven by both moisture and heat conditions.This study reveals the formation mechanism of vegetation water demand patterns in the Lancang River Basin from a plant eco-physiological perspective,providing a scientific basis for the precise management of ecological water resources and protection of vulnerable ecosystems under climate change.