【摘要】 随着造林活动的开展,准确评估人工林的碳储量和固碳能力,对于准确估算全球和区域碳平衡具有重要意义。基于生态系统机理模型为分析和预测人工林生态系统碳储量和碳汇功能的动态特征提供了重要手段。CEVSA2模型是在CEVSA模型的基础上,改进了碳水循环关键过程的定量表达方法而发展的新版本。基于改进后的CEVSA2模型,模拟分析了亚热带红壤丘陵区人工林自造林以来生态系统碳储量和碳通量的变化特征。模拟结果表明,造林后,植被碳持续增加,研究时段内平均每年的增长速率为22%。土壤碳储量在造林后最初的7-8a间是逐渐下降的,而后逐渐升高,约15a后土壤碳增加到初始水平,随后土壤碳继续增加。生态系统的总碳储量也表现为先降低后增加,造林4a后,总碳储量由降低转为增加趋势,6a后,总碳储量即超过造林当年的总碳储量。造林后,总初级生产力和净初级生产力逐渐升高,而总呼吸则先降低后升高,呼吸组分中自养呼吸所占比例逐渐升高而异养呼吸逐渐下降。人工林在造林初期表现为一个碳源,随着人工林的生长,碳汇功能逐渐增强。由此可见,造林初期,生态系统碳储量下降,生态系统向大气释放碳,随着人工林的生长,生态系统转变为一个碳汇,植被碳、土壤碳和总碳储量均显著增加。更多还原

【Abstract】 With the increase of tree plantation areas,how to evaluate accurately their carbon storage and sequestration is significant for estimating global or regional carbon balance.Process-based ecosystem models provide a realistic approach to analyze and predict the dynamic of C storage and fluxes after afforestation.CEVSA2 is a new version of CEVSA with improvements on some key processes of carbon and water cycles.CEVSA2 model was validated and calibrated by eddy flux data in 2003 and 2004 at Qianyanzhou station.The study site is one of the’ChinaFlux network’and located in South China subtropical monsoon climatic zone.After the native vegetation,subtropical evergreen broad-leaved forest,was degraded after a long disturbance,the vegetation was dominated by grass and shrub after 1950s,and then the coniferous plantation has been established since 1983.Based on CEVSA2,we simulated simulated the change of carbon fluxes and storage in grass from 1951 to 1982,and then forest from 1983 to 2004.Based on the CEVSA2 model simulations,we analyzed the change of carbon fluxes and storage of coniferous plantation after afforestation in 1983.The results showed that vegetation C increased at a rate of 22% after afforestation.The soil C decreased in the first 7 to 8 year after planting,and then increased gradually.Soil carbon was equal to the initial value 15 year later.Ecosystem total carbon storage also decreased in the early period after afforestation,and then increased with the growth.Total carbon storage shifted from decreasing to increasing trend in the 4th year after planting,and exceeded the initial value in the 6th year after planting.Gross and net primary productivity increased with the growth.Total ecosystem respiration decreased firstly and then increased.Autotrophic respiration ratio of total respiration increased with growth,and heterotrophic respiration ratio was decreased inversely.All these results showed that the total carbon storage decreased,and ecosystem released carbon to atmosphere during the early period of afforestation.With the growth of forest,ecosystem became a carbon sink,and vegetation,soil and total carbon storage increased obviously.更多还原