Abstract:

Aims Peat wetlands are globally significant carbon sinks and biodiversity hotspots that are particularly sensitive to alien plant invasions. This study focuses on the subalpine peat wetlands of Dajiuhu in Shennongjia, aiming to reveal the impacts of the invasion of Erigeron annuus on the structure and diversity of plant communities, and to analyze the underlying ecological effects and mechanisms.

Methods The effects of invasion were comprehensively assessed by setting up paired invasion and control plots, conducting plant community surveys, analyzing species composition (functional groups) and 11 soil factors, and integrating indicators such as α and β diversity metrics.

Important findings The results showed that invasion led to decline in Poaceae and Juncaceae species, while Asteraceae, some Fabaceae, and Lamiaceae species expanded. Comparisons between invaded and control plots revealed that the dominance of previously dominant native species decreased in invaded plots, resulting in a more even distribution of species abundance. This was reflected in significant increases in the Shannon-Wiener diversity and Pielou evenness indices, while species richness showed no significant difference. However, within the invaded plots, as the dominance of E. annuus gradually increased, community composition became increasingly dominated by E. annuus and a few associated species, leading to an uneven distribution of species abundance. Consequently, Shannon-Wiener diversity and Pielou evenness indices, and species richness all decreased significantly, while the Simpson dominance index increased significantly, reflecting a substantial decline in overall α diversity. β diversity analysis showed that invasion significantly reduced species turnover and community spatial heterogeneity, leading to homogenization of species composition and functional structure. Soil environmental analysis showed that E. annuus prefers habitats with low moisture and nutrients, potentially altering the soil microenvironment through plant-soil feedback mechanisms, thereby further inhibiting wetland plants and affecting community succession trajectories. This study demonstrates the structural reorganization and functional degradation of subalpine peat wetland communities driven by E. annuus invasion, highlights the necessity of establishing long-term monitoring systems and formulating targeted prevention and control strategies, and provides theoretical support for invasive species management in subalpine peat wetlands.

Key words: Shennongjia, Dajiuhu, plant invasion, species diversity, species composition