基于IBIS模型的1960-2006年中国陆地生态系统碳收支格局研究

定量评估区域陆地生态系统碳收支是生态系统与全球变化科学研究的重要科学问题之一。利用集成生物圈模型（IBIS）对中国陆地生态系统历史时期（1960-2006年）气候及CO₂浓度变化条件下碳收支时空变异特征和发展趋势进行了模拟分析。结果表明,1960-2006年间,中国陆地生态系统净初级生产力（NPP）总量水平约为2.46 GtC/a,总体呈上升趋势,在东南及西南地区最高,其次是长白山及大小兴安岭地区,西北内陆地区的净初级生产力水平最低;1960-2006年间,中国陆地生态系统净生态系统生产力（NEP）总量水平约为0.11 GtC/a,总体呈上升趋势,绝大部分区域表现为碳汇效应,大兴安岭、小兴安岭、长白山、东南地区及西南部分地区碳汇效应较强,西北内陆区表现出弱碳源效应,温带湿润区、高原温带区和高原寒带区碳汇效应呈显著上升趋势;中国11个气候区,NPP与降水均为正相关,除了中温带湿润区、寒温带湿润区、高原温带和高原寒带外,降水是限制植被生长的主要因子。除了高原寒带外,NEP同样表现出与降水的更强相关性,与气温的相关性较弱。经验证,IBIS模型对于中国陆地生态系统碳收支的模拟结果合理,可以为科学预测生态系统的固碳潜力和制定区域碳管理政策提供科学依据。

Evaluating the carbon budget pattern of Chinese terrestrial ecosystem from 1960 to 2006 using Integrated Biosphere Simulator

Estimating the carbon budget is one of the most important scientific questions for observing worldwide biological changes. In this study, we used the Integrated Biosphere Simulator (IBIS) to evaluate the effects of climate change and elevated CO₂ concentration on the temporal and spatial variation of carbon budget pattern in the terrestrial ecosystem in China during 1960 to 2006. The results from the model were validated against forestry inventory and flux observation data, and compared with other data from previous publications. The following results were obtained: (1) IBIS accurately simulated the carbon budget pattern of the terrestrial ecosystem of China. The highest net primary productivity (NPP) was observed in southeastern and southwestern China, while the lowest NPP was distributed in northwestern China. (2) The NPP showed an increasing trend from 1960 to 2006 in all climate zones except in the wet-warm-temperate zone. From 1960 to 2006, the total NPP of the terrestrial ecosystem of China showed an increasing trend at a rate of 6 MtC/a and the range of NPP was between 2.2 GtC/a and 2.7 GtC/a, with a mean value of 2.46 GtC/a; peak values occurred in 1990, 1993, 1996, 1998, and 2002. (3) In 11 climate zones, NPP was significantly correlated with precipitation and temperature, and precipitation was the main limiting factor except in the wet-middle temperate, cold temperate, plateau temperate, and plateau frigid zones. (4) The net ecosystem productivity (NEP) showed that most terrestrial ecosystems in China acted as carbon sinks. Only the dry-warm-temperate zone in northwestern China and the southwestern part of the Tibet plateau acted as a small carbon source, while Daxinganling, Xiaoxinganling, and Changbai mountains as well as southeastern and southwestern China acted as large carbon sinks. (5) The NEP showed a significant increasing trend in the wet-middle-temperate, plateau temperate, and plateau frigid zones, while other zones remained in a stable state from 1960 to 2006. The total NEP of the terrestrial ecosystem of China also showed an increasing trend at a rate of 1.6 MtC/a and the range of NEP was between -0.10 GtC/a and 0.25 GtC/a, with a mean value of 0.11 GtC/a from 1960 to 2006. (6) The NEP showed a stronger correlation with precipitation than temperature. Except for temperature, precipitation, increasing CO₂, land-use change, and the program of "Grain for Green" were also among the most important factors caused the change in the carbon budget of China, and the response of terrestrial ecosystem to these factors will be the priority for future research. Above all, IBIS produced reasonable and reliable results on the terrestrial carbon budget in China, and these results can be applied in predicting the potential of carbon sequestration and providing the scientific basis for regional carbon management.