Differential effects of vegetation types on regional carbon stocks in China: A meta-analysis-based integrated assessment of above-ground and surface soil carbon pools

In Chinese terrestrial ecosystems, above-ground carbon (AGC) and surface soil organic carbon (SOC) constitute critical components of vegetation carbon stocks. This study offers a more comprehensive analysis of the mechanisms that influence carbon sequestration. Through a meta-analysis of 173 peer-reviewed studies, the research examined three major natural ecosystems: trees, shrubs, and grasses. Key findings reveal: (1) The trees exhibited the highest carbon sequestration capacity (AGC = 4.73, SOC = 2.34), followed by shrubs (AGC = 1.07, SOC = 2.66) and grasses (AGC = −1.07, SOC = 1.37), with all values compared to control farmland. (2) Regional divergence: Tree AGC was highest in Northeast (13.29) and North China (6.87); Grass AGC was lower than farmland in Inner Mongolia (−7.94), Southeast (−3.56), and Northwest China (−2.21); SOC was most prominent for trees and shrubs in Southwest China (3.77 and 4.48, respectively); Grass SOC peaked in Central China (4.24); Comparative analysis showed tree AGC generally exceeded SOC, while grasses exhibited the opposite pattern; Shrubs demonstrated higher AGC than SOC in northern regions, with the reverse pattern in southern regions. (3) Climatic thresholds: High precipitation (>1500 mm) maximally enhances AGC and SOC capacities for trees and shrubs, with SOC further enhanced at >15 °C; Grasses demonstrate optimal carbon sequestration under moderate conditions (5–15 °C and 1000–1500 mm). These findings emphasize the critical importance of considering vegetation type, regional heterogeneity, and climatic thresholds in developing forest management strategies for enhanced carbon sink optimization. The study provides valuable insights for ecosystem-specific carbon management approaches in China's diverse terrestrial environments.