Tree species diversity and structural complexity drive the stability of productivity in subtropical forest restoration

Abstract

The stability of forest productivity is shaped by biodiversity and species asynchrony, the temporal variation in species’ productivity, and also by stand structural attributes, yet their contributions to forest restoration remain unclear. Here, we assessed how optimizing structural complexity can enhance stability by analyzing 13-year data from 201 restored subtropical plantation plots. Using structural equation modeling, the effects of tree diversity (species richness and functional and phylogenetic diversity), stand structure, functional composition, topography, and soil nutrient availability on productivity stability were quantified. Our results indicate that higher tree species richness, functional and phylogenetic diversity, structural complexity, and stand density positively influenced productivity and its temporal stability primarily via increased species asynchrony. Stands dominated by acquisitive species, characterized by higher specific leaf area, and leaf nitrogen and phosphorus levels, exhibited greater stability. In contrast, increased elevation and steeper slopes negatively affected stability, whereas higher soil nutrient availability had a positive effect. These findings highlight the critical roles of tree diversity and stand structure in achieving both high productivity and stability in the restoration of subtropical forests. Maintaining a proportion of acquisitive species and establishing dense, structurally complex, and functionally diverse stands can therefore be an effective strategy to enhance forest productivity and its resilience.

Keywords

Forest productivity stability / Tree diversity / Structural complexity / Functional trait composition / Subtropical forest restoration

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