Abstract:The carbon stocks and dynamics in Acacia mangium plantation ecosystem in Heshan, Guangdong Province were simulated from 1985 to 2100 by BIOME-BGC Model. The results showed that the biomass of Acacia mangium plantation increased rapidly in the first 12 years, and then increased slowly up to 300 t hm-2. The proportions of biomass allocated to leaves, stems and roots were 4.35%, 73.91% and 21.74%, respectively. The carbon storage at the ecosystem level had the similar tendency, it reached 325 t C hm-2 at last, and the proportions of carbon storage in vegetation, soil and litter fall were 43.08%、52.30% and 4.62%, respectively. It was found that the net primary productivity (NPP) of Acacia mangium planation was high at the age of 4 to 12 years up to 11 t hm-2, and then stabilized at 3~6 t hm-2 later. The leaf area index (LAI) increased rapidly at the first three years and reached 7.84 at 5-year-old, but then decreased to 2.7~5.0. It indicated that LAI might be the main control factor of NPP by regression analysis. Our simulation results demonstrated that the Acacia mangium planation grew fast at the first 12 years. when Acacia mangium was used as pioneer tree species for forest vegetation restoration in lower subtropical region, it suggested on taking stand improvement after the age of 12 years.