Biodiv Sci ›› 2021, Vol. 29 ›› Issue (11): 1435-1446.

• Original Papers:Plant Diversity •

### Relationships between tree diversity and biomass/productivity and their influence factors in a lower subtropical evergreen broad-leaved forest

Jie Zhu1,2,3,4,5, Anchi Wu1,2, Shun Zou6, Xin Xiong1, Shizhong Liu1, Guowei Chu1, Qianmei Zhang1, Juxiu Liu1, Xuli Tang1, Junhua Yan1, Deqiang Zhang1, Guoyi Zhou7,*()

1. 1 South China Botanical Garden, Chinese Academy of Sciences, Guangzhou 510650
2 College of Resources and Environment, University of Chinese Academy of Sciences Beijing, 100049
3 Surveying and Mapping Institute Lands and Resource Department of Guangdong Province, Guangzhou 510663
4 Key Laboratory of Natural Resources Monitoring in Tropical and Subtropical Area of South China, Ministry of Natural Resources, Guangzhou 510663
5 Guangdong Science and Technology Collaborative Innovation Center for Natural Resources, Guangzhou 510663
6 Guizhou University of Engineering Science, Guiyang, 551700
7 School of Applied Meteorology, Nanjing University of Information Science & Technology, Nanjing 210044
• Received:2021-01-12 Accepted:2021-10-25 Online:2021-11-20 Published:2021-11-23
• Contact: Guoyi Zhou

Abstract:

Aim The relationship between biodiversity and ecosystem function contribute to productivity, both directly and indirectly. Therefore, it is a critical issue of ecology. The aim of this study is to quantitatively explore the relationship between tree diversity and biomass or productivity of subtropical natural forest ecosystems in late successional stages.
Methods Based on long-term community surveys of topographies and soil nutrients from permanent forest ecosystems in the subtropical evergreen broad-leaved forest, we analyzed the relationship between tree diversity and productivity/biomass and their influencing factors. In this analysis, the correlations between tree diversity and each factor were evaluated using a Pearson correlation analysis. The single and shared effects of each factor were quantified by variance partitioning analysis (VPA). In addition, the relationships between soil nutrients and topographies and their effects on productivity and biomass were further evaluated, either directly or indirectly, through species and structural diversity by using a structural equation model (SEM).
Result Species diversity displayed a negative correlation with biomass and a positive correlation with productivity. Contrarily, structural diversity was positively correlated with biomass and negatively correlated with productivity. The effects of environment factors on tree diversity and biomass/productivity were varied. Specifically, soil moisture had a significant effect on productivity, species diversity was correlated with soil nutrients and topographies, and structural diversity was strongly related to soil nutrients. The variance partitioning analysis results indicated that the single effect of structural diversity explained the largest portion of variance in biomass (35.39%) and productivity (5.21%), followed by the shared effect of structural and species diversity on biomass (13.66%) and productivity (3.53%). Soil nutrients and topographies explained less variation in productivity and biomass. The structural equation results analysis indicated that structural diversity had a direct positive effect on biomass, and biomass had a strong direct negative effect on productivity. Structural diversity indirectly reduced productivity by increasing biomass. Soil nutrients and topographies were mainly affected by biomass, while productivity indirectly affected tree species and structural diversity.
Conclusions These results indicate that (1) species diversity had the greatest direct effect on productivity, and structural diversity had the greatest direct effect on biomass in southern subtropical evergreen broad-leaved forests; (2) species diversity explained productivity better than structural diversity, while structural diversity explained biomass accumulation better than species diversity; and (3) both species diversity and structural diversity can be affected by soil nutrients and topographies.