Seasonal dynamics of herb diversity, soil nutrients and enzyme activities in a northern subtropical forest with Moso bamboo (Phyllostachys edulis) invasion

Moso bamboo (Phyllostachys edulis) invasion has profound and complex effects on the structural composition of adjacent forest vegetation communities as well as on soil physicochemical properties. However, the effects of bamboo invasion on herb diversity, soil properties and enzyme activities in northern subtropical forest ecosystems remain largely unexplored. In this study, seasonal variations in these factors were investigated in a northern subtropical forest in Jiangsu Province, China, where invasion by Moso bamboo was absent, partial, or complete. The results showed that seasonality significantly affected herb species richness and that the Shannon-Wiener diversity index and soil pH increased by 28.69–36.98 % and 4.06–7.7 %, respectively, during the invasion. Seasonal mean soil organic carbon and total nitrogen decreased by 10.57–18.43 % and 7.74–9.03 % in partial and complete invasion stages. Notably, these nutrients exhibited higher concentrations in the stands partially invaded than in those at different invasion stages during the summer. PLS-SEM indicated that soil invertase and acid phosphatase activities were significantly negatively and positively affected by season (p < 0.01), respectively. Invasion stage significantly affected urease and acid phosphatase activities (p < 0.05), with soil pH and alkaline nitrogen acting as mediators, respectively. Our findings highlight the high complexity and spatiotemporal heterogeneity of ecosystem responses to Moso bamboo invasion, underscoring the critical importance of comprehensive and monitoring over multiple seasons.