Developing age-site-density integrated biomass carbon storage models and accumulation tables for warm temperate forests in China

Forest carbon sequestration rate is closely linked to stand growth dynamics; however, existing carbon storage models for warm-temperate forests in China have largely focused on individual factors such as stand age or density, without jointly accounting for site quality and stand density. This limitation constrains their applicability for multi-factor carbon accounting across varying site and management conditions. Using data from China's 7th- 9th National Forest Resource Inventories (2004–2018), we developed carbon storage accumulation models and corresponding tables for typical warm-temperate forest types incorporating forest age, site class, and stand density index (SDI) as predictors. The models achieved satisfactory performance ( R 2 ≥ 0.647), with higher accuracy for natural forests than plantations, and for coniferous than broad-leaved species. Site quality was the primary factor associated with the asymptotic carbon storage parameter ( a ), which decreased from site class I to V. High-density stands stored more carbon than low-density stands, and the relationship between stand density and carbon storage was stronger in natural forests than in plantations. Taking Pinus tabuliformis as a representative species, dynamic simulations driven by the accumulation tables revealed that plantations accumulated carbon more rapidly-during the early stage (<30 years); however, beyond 65 years, plantation growth slowed markedly and the annual carbon sequestration of natural forests began to exceed that of plantations, underscoring the superior long-term sequestration potential of natural forests. Collectively, these models, tables, and comparative analyses provide methodological and technical support for accurate carbon measurement, potential assessment, and the formulation of differentiated, carbon-oriented management strategies for warm-temperate forests in the context of carbon neutrality.