Abstract Forest succession drives major shifts in carbon cycling, but how successional changes in plant functional type (PFT) composition modulate ecosystem‐level carbon dynamics remains poorly quantified. By integrating the cohort‐based Vegetation Demographic Model (VDM; i.e. BiomeE), with a novel traceability framework, we mechanistically resolve carbon cycle dynamics throughout subtropical forest succession. Coupled with BiomeE, our framework partitions transient carbon storage into: (i) carbon storage capacity ( Xc ) and potential ( Xp ); (ii) net primary production (NPP), carbon residence time ( τ N ), net carbon pool change ( X' ) and carbon chasing time ( τ ch ); (iii) carbon allocation, transfer and turnover rates. We applied this integrated approach to a 150‐year subtropical forest chrono sequence (three 50 m × 50 m plots; 72 species across five PFTs), rigorously validating model outputs against field observations. The results showed that early succession (15~25 years) exhibited high PFTs diversity, driving rapid increases in Xc and Xp . As succession progressed, deciduous PFTs declined and evergreen broadleaf trees dominated carbon dynamics, with ecosystem carbon storage reaching approximately 40 kg C m −2 during the mid‐succession stage (70~80 years). In the late‐successional stage (140~150 years), ecosystem carbon storage stabilized at 75 kg C m −2 , closely approaching Xc , which is supported by high NPP (1.37 kg C m −2 year −1 ) and long τ N (70 years), while Xp and carbon sink strength declined. During succession, evergreen broadleaf trees dominated carbon sequestration (83.73%), followed by evergreen needleleaf trees (8.11%), evergreen broadleaf shrubs (5.24%), deciduous broadleaf trees (2.39%) and deciduous broadleaf shrubs (0.52%). Synthesis . By integrating BiomeE and the traceability framework, we deliver a powerful tool to trace mechanistic drivers of carbon dynamics. Our findings reveal that successional PFT shifts, especially towards evergreen dominance, are primary controls on long‐term carbon sequestration in subtropical forests.
Chen et al. (Wed,) studied this question.