Vegetation change mechanism and key driving factors in complex terrains, China

Under global climate change, vegetation dynamics in complex terrains exhibit distinct response patterns to altered hydrological cycles, but the response mechanism and the driving factors are unclear in complex terrains. As most previous studies have underlying surface conditions simple, it is difficult to understand the mechanism in complex terrains. Therefore, this study taking the water conservation area of the Yellow River in China with complex terrains as an example, comprehensively integrated time-series analysis, wavelet transforms, and grey correlation modeling to decode vegetation change mechanisms. Further analyzes are made to explore the temporal trends and spatial patterns of the key driving factors. Our multi-method approach reveals that temperature and soil water content are the key factors driving the spatial and temporal vegetation change with temperature ranking the first. Climate change affected the changes of temperature and soil water content in the basin, resulting in the abrupt change of vegetation coverage in 2000-2005. Vegetation coverage fluctuated downward before 2000 then surged after 2000, aligning with soil water content increases and sustained temperature rises till 2020. Sub-watershed analyses identified consistent 6-7a precipitation cycles but temperature and soil water content are stable. We found that environmental policies and GDP growth emerged as key anthropogenic amplifiers, enhancing vegetation resilience through synergistic effects with climatic factors. These methodologies and findings provide scientific support for the ecological restoration of the Yellow River Basin and offer global implications for similar complex terrains, particularly in developing climate-adaptive vegetation restoration strategies.