Spatiotemporal Dynamics and Climatic Drivers of Ecological Vulnerability in Northern Hemisphere Mid- to High-Latitude Terrestrial Ecosystems

Climate change is reshaping the terrestrial ecosystem patterns of the Northern Hemisphere, with ecological vulnerability being particularly pronounced in middle and high latitudes under the influence of Arctic amplification. However, a systematic quantification of the spatiotemporal evolution of ecological vulnerability across different ecosystem types and their dominant climate driving mechanisms remains lacking. Based on MODIS NDVI, CRU, and ERA5-Land climate reanalysis data from the 2001~2023 growing seasons, this study constructed an integrated sensitivity-adaptive capacity assessment framework to systematically evaluate the spatiotemporal dynamics of ecological vulnerability for three ecosystems north of 30°N: forest, other woody vegetation, and grassland. Structural equation modeling was used to identify the key climate driving mechanisms. The results indicate that: (1) Ecological vulnerability showed distinct spatial heterogeneity, with high-value areas (EV > 0.30) concentrated in high-latitude permafrost degradation zones and low-value areas (EV < 0.30) mainly distributed in temperate humid regions; (2) Temporally, the overall ecosystem vulnerability decreased during 2013~2023 compared to 2001~2012, with forests showing the most significant improvement and the highest stability, while grassland ecosystems exhibited the highest vulnerability with limited improvement; (3) The climate driving mechanisms differed significantly among ecosystems: air temperature was the dominant factor suppressing ecological vulnerability, with its effect strongest at high latitudes; increased surface solar radiation significantly exacerbated vulnerability in mid-latitude ecosystems; increased precipitation suppressed forest vulnerability but exacerbated grassland vulnerability in mid-latitude regions. This study reveals the differential responses of various ecosystems to climate change and their underlying driving mechanisms, emphasizing the necessity for differentiated ecological management strategies and providing a scientific basis for addressing future climate risks.