午潮山次生常绿阔叶林树木多样性与生产力的关系及其驱动因素OACHSSCD

This study aimed to investigate the effects of tree diversity(including species diversity and structural diversity)and soil factors on forest productivity,clarify the driving mechanisms of productivity in secondary evergreen broad-leaved forests in Zhejiang Province,and provide a theoretical basis for the sustainable management and enhancement of ecosystem services in subtropical secondary forests.A 6 hm2 dynamic monitoring plot was established in a secondary evergreen broad-leaved forest on Wuchaoshan National Forest Park in Zhejiang Province.Based on data from two phases of community surveys conducted in 2020 and 2024,linear regression,Pearson correlation analysis,and structural equation modeling(SEM)were employed to analyze the correlations among species diversity,structural diversity,and soil factors within the Wuchaoshan secondary evergreen broad-leaved forest,and to quantify their relative contributions to forest productivity.The results showed that:(1)During 2020-2024,the total stand productivity of the monitoring plot was 7.95 t hm-2 a-1.The dominant species Schima superba contributed 4.71 t hm-2 a-1,accounting for 59.22％of total productivity,indicating that dominant species play a leading role in ecosystem production function.(2)No significant correlation was found between species diversity and productivity,while structural diversity significantly increased productivity(P＜0.01).(3)Among soil factors,soil bulk density showed an extremely significant negative correlation with productivity(P＜0.01),whereas total nitrogen,available nitrogen,and organic carbon were positively correlated with productivity(P＜0.05).(4)SEM results indicated that soil factors had a strong direct positive effect on structural diversity(path coefficient,PC=0.271,P＜0.01)and an indirect effect on species diversity;in turn,structural diversity exerted a direct positive effect on productivity(PC=0.228,P＜0.05).This study reveals the key drivers of productivity in the secondary evergreen broad-leaved forest of Wuchao Mountain:the high contribution of the dominant species(S.superba)supports the mass ratio hypothesis;the significant promoting of productivity by structural diversity aligns with niche complementarity and is further linked to the high growth potential of young-to-middle-aged regenerated trees.Soil factors indirectly affected productivity by directly regulating structural diversity,which reflects environmental filtering.The"soil-structural diversity-productivity"pathway represents the core driving mechanism of the secondary evergreen broad-leaved forest ecosystem.Based on these findings,we recommend integrated management strategies-such as optimizing stand spatial structure,rationally allocating dominant species with key functional traits,and improving soil physical structure-to enhance the ecosystem functions and services of subtropical secondary evergreen broad-leaved forests.