Climate and land use regulate vegetation-runoff interaction pathways in the three-river source region.

Area of Science:

• Alpine hydrology
• Climate change impacts
• Ecosystem dynamics

Background:

• Alpine ecosystems are vital for water regulation but vulnerable to climate change.
• The Three-River Source Region (TRSR) faces altered climate and ecological conditions impacting vegetation and hydrology.
• Quantifying combined climate and ecological effects on runoff is crucial.

Purpose of the Study:

• To evaluate the relative impacts of climate, vegetation phenology, and land cover on runoff variability in the TRSR.
• To understand the mediating role of vegetation dynamics in alpine hydrological processes.

Main Methods:

• Utilized Partial Least Squares Structural Equation Modeling (PLS-SEM).
• Analyzed data from 1982 to 2018, considering temperature, precipitation, vegetation phenology, and land cover.
• Assessed direct and indirect effects on runoff variability.

Main Results:

• Vegetation growth status (GS) showed significant interannual and spatial variation, increasing annually.
• Precipitation had a strong positive direct and indirect effect on runoff.
• Temperature exhibited a strong negative direct effect, with indirect effects partially offsetting it.
• High-density forest positively influenced runoff by regulating soil moisture and evapotranspiration.
• Vegetation growth status served as a key mediator between climate and runoff.

Conclusions:

• Vegetation dynamics play a central role in alpine hydrology, modulating soil moisture and evapotranspiration.
• Understanding these interactions is vital for adaptive environmental management in alpine headwaters.
• Effective management is needed to sustain water resources and ecosystem function under changing conditions.