Aspect Matters: Unraveling Microclimate Impacts on Mountain Greenness and Greening

Abstract

Abstract Mountains are vital ecosystems, yet predicting plant growth there is complex due to diverse microclimates on slopes. Equatorial‐facing slopes (EFSs) are drier and warmer, and polar‐facing slopes (PFSs) are wetter and colder, than their regional macroclimates. Analyzing Moderate Resolution Imaging Spectroradiometer normalized difference vegetation index from 2003 to 2021, we identified a clear geographic pattern of differences in greenness on the two opposite aspects: EFSs were greener than PFSs in cold areas and were browner in dry areas, mainly determined by the relative importance of limitations of temperature and water. PFSs had stronger greening trends than did EPSs, leading to a weakening difference in greenness between EPSs and PFSs in temperature‐limited areas, and an intensifying difference in water‐limited areas. This suggests the alleviation of temperature limitation and exacerbation of water limitation. Montane ecosystems constitute a “natural laboratory” for deepening our understanding of the temporal evolution of the climatic control of vegetation growth with a space‐for‐time substitution.