Abstract: Aims: Reconstruction of near-natural forest is an important approach to accelerate the recovery of urban vegetation and forest restoration. However, the spatial and temporal dynamics of species diversity, canopy structure and biomass during subtropical forest restoration remain unclear, especially in highly urbanized regions. Methods: Based on a long-term subtropical near-natural forest plant community that planted with native plant species in 2006 located in Minhang District of the megacity Shanghai, we did the resurvey of plant community in 2023, and compared with the compositional changes of plant community through five historical surveys of core plots from 2007 to 2023. Aboveground biomass and the relations among biomass, plant richness and canopy height across temporal and spatial scales were analyzed using general linear regression. Results: Along with near-natural forest succession, woody plant richness increased from 11 in 2007 to 18 in 2023, and stem density increased at early stages and then decreased. The aboveground biomass increased from 3.51 t/ha in 2007 to 208.83 t/ha in 2023. Evergreen tree species such as Camphora officinarum and Quercus myrsinifolia gradually became the dominant species. Aboveground biomass showed significant positive correlations with species richness (P < 0.01) and mean tree height (P < 0.001), and a significant negative correlation with stem density (P < 0.01). When comparing the compositional changes over space, at three scales of 5 m, 10 m and 20 m, the relations between biomass and stem density remains highly significantly positive (P < 0.001), but the relations with mean height shifted from nonsignificant at 5 m scale to significantly negative at 10 m (P < 0.05) and 20 m (P < 0.05) scales. Conclusion: During the 17-year subtropical forest restoration, the model of near-natural forest construction has clearly exhibited its efficacy in accelerating the succession process. These preliminary findings suggest that, during the construction and restoration of near-natural forests, we should pay attention to the dominant role of native tree species, and consider diverse species composition to effectively promote plant diversity and carbon storage.

Key words: Urban near-natural forest, species diversity, biomass accumulation, community succession, subtropical forests