Different response patterns of vegetation to environmental changes during the mid-to-late Holocene: Pollen evidence from an alpine lake in Western Sichuan Province, southwestern China

Abstract

Understanding long-term vegetation responses to environmental change is essential for predicting ecosystem resilience under future climate scenarios. We used high-resolution mid-to-late Holocene pollen records from an alpine lake in southwestern China to reconstruct vegetation dynamics over the past ∼ 5000 years, revealing distinct response patterns between alpine shrub–herb communities and forests. Results showed that alpine shrub–herb vegetation, highly sensitive to climate fluctuations, exhibited increasing turnover rates after 4410 cal. yr BP, whereas tree vegetation gradually stabilized before ∼ 3000 cal. yr BP. After 500 cal. yr BP, turnover rates accelerated in both shrub–herb communities and forests, with intensified variability in forests and declining coverage in shrub–herb communities, likely driven by climate cooling and intensified human activity. Principal Component Analysis (PCA) results indicated that temperature primarily controlled coverage of shrub–herb communities, while precipitation mediated tree abundance variations. Structural Equation Modeling (SEM) identified CO₂ and precipitation as the dominant drivers of shrub and herb community turnover rates, whereas forest turnover rates responded mainly to temperature. Crucially, shrub–herb communities, with higher turnover rates and a stronger contribution to species richness, responded more rapidly to climatic shifts, whereas forests influencing species evenness provided long-term ecosystem stability. These findings offer novel insights into vegetation change mechanisms and enhance understanding of mountain ecosystem resilience under environmental change.