马占相思人工林生态系统的碳格局及其动态模拟

The Simulation on Carbon Stocks and Dynamics in Acacia mangium Plantation Ecosystem

采用BIOME-BGC模型对广东鹤山的马占相思（Acacia mangium）人工林生态系统1985-2100年间的碳格局及其动态变化进行了模拟。结果表明，马占相思生物量在前12a增长较快，之后增长缓慢，最终达到300t hm^-2；预计2100年马占相思生物量在于、根、叶中的分配分别为73.91％、21.74％和4.35％。马占相思人工林的碳贮量在前12a增长较快，之后增长缓慢并最终维持在325t C hm^-2左右，在造林初始阶段主要分布于土壤中，之后在植被、土壤和凋落物3大碳库中的分配分别为43.08％、52.30％和4.62％；马占相思净初级生产力（NPP）在4-12a较大，最大可达11t C hm^-2，之后下降至3-6t C hm^-2；马占相思叶面积指数（LAX）前3a增长迅速，5a达到7.84，之后下降，约为2.7-5.0；LAJ与NPP的回归分析结果显示LAI可能是限制马占相思林NPP增长的主要因子。模拟结果还显示马占相思林前期生长迅速，但随后生长缓慢，叶生物量还出现负增长现象。因此，我国南亚热带地区在以马占相思作为先锋树种进行地带性森林植被恢复时，可在12a后进行林分改造。

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 300t 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 3-6t 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.