Abstract: We analyzed species diversity of arbor forests and its relationship with spatial structure and soil factors at different successional stages of Tianmu Mountain National Nature Reserve in Zhejiang Province, including conife-rous and broad-leaved mixed forest and evergreen broad-leaved forest. The results showed that as the coniferous and broad-leaved mixed forest successionally advanced to the evergreen broad-leaved forest, the number of species increased from 51 to 62. In the top 10 species ranked by importance value, the proportion of Fagaceae species increased from 27.7% to 42.3%. Simpson index and Pielou evenness index differed significantly at different succession stages, decreasing from 0.79 to 0.77 and 0.91 to 0.86. In the coniferous and broad-leaved mixed forest stage, competition index was significantly positively correlated with Shannon index and species richness. Complete mingling was significantly positively correlated with Simpson index, Shannon index, and Pielou evenness index. Aggregation index was significantly negatively correlated with Simpson index, Shannon index, and species richness. Hydrolytic nitrogen and available potassium were significantly positively correlated with Pielou evenness index and significantly negatively correlated with species richness. In the evergreen broad-leaved forest stage, aggregation index was significantly negatively correlated with Shannon index and species richness. Complete mingling was significantly positively correlated with Simpson index, Shannon index, and Pielou evenness index. Shannon index and species richness were significantly negatively correlated with hydrolytic nitrogen and significantly positively correlated with available phosphorus. Simpson index, Shannon index, and species richness were significantly positively correlated with organic matter content. Spatial structure explained more variations of species diversity than soil factors at different successional stages. Aggregation index and complete mingling were the main spatial structure factors affecting species diversity. In conclusion, we recommended to focus on regulating spatial structure and to adjust soil physicochemical properties according to the succession stage to protect species diversity of arbor forests in different succession stages in Tianmu Mountains.

Key words: Tianmu Mountains, succession, spatial structure, soil, species diversity