The Effect of Stand Structural Diversity on Carbon Storage and Forest Productivity: A Meta-analysis Study

Stand structural diversity (SSD) is an emerging factor considered in forest management to facilitate carbon storage because altering SSD could facilitate forest growth for more carbon storage. However, the effects of SSD on carbon storage and productivity are inconsistent across studies, and drivers of the inconsistency remain unknown. To address this knowledge gap, we conducted a comprehensive meta-analysis to understand the SSD effects based on studies of different forest ecosystems around the world. We then used meta-regression to evaluate which factors contribute to the inconsistency in SSD effects. Our results showed that (1) there is a significant amount of heterogeneity in the SSD effects on carbon storage and productivity between different studies, (2) The above heterogeneity is significantly related to average tree size, max tree size, basal area, species richness, and stand age. Overall, the SSD effects are context-dependent, and we identified the eco-physiological mechanisms causing the heterogeneity. These outcomes will improve the understanding of SSD and inform SSD-based forest management to enhance forest productivity and carbon storage.