The effects of environmental factors and plant diversity on forest carbon sequestration vary between eastern and western regions of China.

Forest ecosystems play a crucial role in global carbon sequestration, with the majority of forest carbon being stored in biomass. However, it remains unclear at the national scale to what extent forest biomass depends on soil and climatic conditions, as well as tree species diversity. In this study, we identified and grouped these factors using a classical geographical dividing line, the Hu-line, which divides China into East and West regions characterized by obvious differences in natural conditions and vegetation distribution. We assessed the possible effects of forest species diversity, climatic conditions, and soil environment on the magnitude of forest biomass and carbon sequestration potential by integrating China's 2009–2018 forest inventory data with environmental information. We tested these effects using a structural equation model. Forest biomass was mainly influenced by environmental factors in the West (effect sizes soil N, soil pH, soil P, mean annual precipitation and temperature: −0.50, 0.41, 0.10, 0.04, 0.34) and by species diversity in the East (effect sizes −0.26 and 0.44 in the west and east, respectively). Our results demonstrated the non-negligible influence of forest species diversity on forest biomass. Therefore, through a comprehensive consideration of the interactions between climate, soil, and water resource availability, forest management and cleaner production plans will assist policymakers in designing a rational framework for future forest conservation measures. [ABSTRACT FROM AUTHOR]