Hydrothermal response to changes in snow and vegetation cover in Xinjiang, China.

Xinjiang is a cold and arid region, where shifts in the hydrothermal environment directly influence the stability of its diverse ecosystems. Global warming has resulted in substantial changes to snow and vegetation cover, but their impact on regional hydrothermal conditions and the underlying mechanisms remain unclear. In this study, Xinjiang was divided into four geographical units representing different ecosystems: mountains, oases, basins, and transition zones. Remote sensing and meteorological reanalysis data for 2001-2024 were then integrated to comprehensively analyze the spatiotemporal characteristics of the snow cover, vegetation cover, albedo, and hydrothermal variables for Xinjiang. The results showed that the vegetation cover has been gradually increasing (k = 0.001) while the snow cover has persistently declined over the study period (snow cover month (SCM), k = -0.01 and snow cover fraction (SCF), k = -0.001). Thermal variables such as the land surface temperature, air temperature, and latent heat flux have generally increased while hydrological variables such as the precipitation and vapor pressure deficit have decreased slightly. Across all geographical units, the snow cover and albedo had a significantly positive correlation while the vapor pressure deficit and latent heat flux generally had a significantly negative correlation. Snow cover proved to be the dominant factor governing changes in the regional hydrothermal response via its effect on the albedo, which displayed pronounced spatial heterogeneity depending on the geographical unit. In contrast, vegetation cover had a relatively weak influence on hydrothermal variables and only significantly affected the vapor pressure deficit. The identified hydrothermal regulation mechanism (i.e., snow-dominated, vegetation-assisted) provides a scientific basis for ecological conservation and water resource management in Xinjiang.