Vegetation Phenological Differences Between Polar‐ and Equatorial‐Facing Slopes in the Three Rivers Source Region, Tibetan Plateau

Abstract

AbstractVegetation growth is influenced by the microclimate driven by aspects, as evident in the asymmetric vegetation greenness on polar‐facing slopes (PFS) and equatorial‐facing slopes (EFS). However, it remains uncertain whether aspects influence vegetation phenology. To address this question, we defined the aspect‐induced phenological differences between PFS and EFS from 2019 to 2022 within each 3 × 3 km2 grid, using average phenological metrics extracted from Sentinel‐2 data. We found that the start of the growing season (SOS) occurs earlier on EFS in cold and humid regions, but in arid areas, PFS has an earlier SOS. The end of the growing season (EOS) consistently occurred later on EFS due to radiation limitations in autumn phenology. Employing the space‐for‐time approach, the observed distribution of phenological differences within the climate space could potentially indicate the phenological trends of different slope orientations in the future. Our study provides valuable insights into topographic regulation on vegetation phenology.