2000-2022年青藏高原植被覆盖地形分异效应OACHSSCD

Understanding the vegetation distribution patterns across different topographic conditions of the Tibetan Plateau is essential for assessing alpine climate responses,ecosystem conservation,and biodiversity maintenance.This study investigates the spatial differentiation of vegetation on the Tibetan Plateau under varying elevation,slope,and aspect conditions,based on Enhanced Vegetation Index(EVI)data from 2000 to 2022 and DEM-derived topographic information.Trend analysis and topographic correction methods were employed to assess vegetation dynamics.The results show that:(1)overall,76.45％of the vegetation exhibited an improving trend,and this improvement was mainly distributed in regions such as the Hoh Xil Mountains,the Qiangtang-Wenjia Ri area,and the northern Bayan Har Mountains.These areas generally showed stable or gradually enhanced vegetation conditions throughout the study period.In contrast,2.2％of the vegetation experienced significant degradation,primarily located in the Qaidam Basin,the eastern Dongbuli Mountains,and the western Bayan Har Mountains.(2)Vegetation located on sunny slopes generally exhibited better growth conditions than vegetation on shady slopes.This pattern may be related to the fact that climate warming has intensified permafrost thawing and snowmelt on sunny slopes,which in turn increases the amount of available soil moisture.At the same time,a longer duration of sunshine on sunny slopes can further enhance vegetation photosynthesis,and the combined effect of increased water availability and extended solar radiation may jointly promote vegetation growth.(3)The EVI values showed an overall linear decrease with increasing elevation.However,in the 2000-3000 m elevation range,EVI values were anomalously low,even lower than those in the 3000-4000 m range.This pattern is mainly attributed to the Qaidam Basin,which dominates this elevation band.The surrounding mountains block moisture transport into the basin,leading to extremely low precipitation and sparse vegetation cover.When the elevation exceeds 4000 m,EVI values generally fall below 0.2,indicating that vegetation becomes increasingly limited and gradually disappears as environmental constraints strengthen with elevation.Findings(2)and(3)differ from the commonly reported conclusions that"low elevation,gentle slopes,and shady aspects favor vegetation growth,and that vegetation indices typically show a nonlinear relationship with elevation(increasing first and then decreasing)."This suggests that vegetation dynamics on the Tibetan Plateau do not follow the same ecological patterns observed in non-plateau regions.Therefore,ecological conservation strategy should prioritize the 2000-3000 m elevation zone,where vegetation cover is constrained by limited precipitation,and future efforts should strengthen long-term ecological monitoring and biodiversity protection in key degradation areas such as the Qaidam Basin and western Bayan Har Mountains to promote vegetation restoration and ecosystem stability.