The Universal but Weak Positive Correlation Between Plant Diversity and Carbon Storage: Evidence From a Global Synthetic Analysis

ABSTRACT Research has yielded conflicting quantitative conclusions regarding the relationship between plant diversity and carbon storage, leaving the nature of this correlation at the global scale unresolved. Here, this study quantitatively evaluated the strength of this ecological association through a synthetic analysis of 285 plant diversity–carbon storage pair correlations from 115 studies published globally. Our findings demonstrate that although substantial heterogeneity exists among different categories, a consistent yet weak positive correlation ( r < 0.4) emerges globally between plant diversity and plant/soil carbon storage. The correlation between species richness and plant carbon storage is more obvious. Notably, in grassland, there is a moderate probability (Shannon diversity–soil carbon stock: 65.4%; species richness–soil carbon stock: 55.2%) of observing a strong correlation ( r > 0.7) between plant diversity and soil carbon storage. Furthermore, climatic thresholds (MAT = 13.12°C, MAP = 752 mm, AI = 0.86) demarcate significant modulation of the species richness–plant carbon storage relationship. Beyond these thresholds, the species richness–plant carbon storage correlations showed increases of 91.24% in high‐temperature regions, 73.13% in high‐precipitation zones, and 54.59% in low‐aridity environments. These findings redefine our understanding of the correlation between plant diversity and carbon storage at the global scale. We recommend linking the biodiversity and carbon sequestration functions of ecosystems when formulating biodiversity conservation and carbon management strategies and to fully consider the principle of zoned management.