作 者 ：吕超群, 孙书存
期 刊 ：植物生态学报 2004年 28卷 5期 页码：692-703
Keywords:Carbon pools, Terrestrial ecosystems, Distribution patterns, Influence factors,
摘 要 ：准确了解陆地生态系统中碳密度的时空格局及其影响因子和作用机制，对于估算和预测不同类型生态系统中的植被和土壤的碳存储能力、判定碳汇、制定缓解全球变化的合理政策措施，具有重要意义。该文综述了现有研究中发现的世界陆地生态系统碳密度空间分布的地带性规律及中国陆地生态系统碳密度格局的独特特点。在全球尺度上，植被碳密度分布与植物生物量格局基本一致，除北方森林外其余大部分随纬度升高而减小；土壤碳密度则随纬度升高而增大。陆地生态系统中北方森林和热带森林的总体碳密度最高，不同的是，前者的碳主要集中在土壤中，而后者则集中在植被中。但在区域尺度上，由于气候、地形及人类活动影响，这种规律性可能会发生变化甚至不起作用。水热条件、土壤养分、生物多样性、气候和大气CO2浓度的变化以及土地利用与覆盖变化等是碳密度空间格局形成和发生变化的驱动因子。在某一特定区域，它们通过直接或间接提高植被净初级生产力，抑制呼吸和分解作用来增加陆地生态系统碳密度。综合分析特定时空条件下各因子对碳存储量的影响是解释碳密度分布现状，预测碳密度格局变化的关键，但目前的研究对各项驱动因子的作用机制、影响强度及多个因子间的相互作用仍不是很清楚，需要加强该方面的研究力度。碳密度研究中的数据获取、机理分析和过程模拟等方面仍存在很大的不确定性，因此有必要建立规范统一的碳密度测量估算系统和更为精准有效的估算模型，进行多尺度、多精度水平的综合研究。
Abstract:Terrestrial ecosystems are a large carbon density and play an important role in the global carbon budget and mitigating global warming by carbon sequestration. To encourage additional carbon sequestration and storage in global vegetation and soils, we need to be clear about the distribution patterns of carbon density and the factors that influence these patterns. Therefore, the characteristics of the distribution patterns of carbon density in terrestrial ecosystems of the world and China are reviewed in this paper. At the global scale, the distribution of carbon in vegetation corresponds with the spatial pattern of biomass and generally decreases from low-latitude to high-latitude with the exception of boreal forests. In contrast, soil organic pools of carbon increase along the same gradient. The largest stores of carbon in biomass are in tropical and boreal forests, and the largest stores of soil carbon are in the high latitude ecosystems (boreal forest and tundra). Total carbon density of both vegetation and soils are highest in tropical and boreal forests. In the tropics more carbon is stored in vegetation than in soils, while in the boreal region far more carbon is stored in the soils. At the regional scale, these patterns might vary due to differences in climate, topography and human influence among regions. Several major factors, including climatic conditions, soil nutrients, biodiversity, climate and atmospheric CO2 changes, land use and cover changes, all contribute to the storage and maintenance of carbon. For example, carbon density will be high in regions where temperature and precipitation are favorable for abundant plant growth. The enhanced carbon sequestered in response to elevated levels of CO2 or nitrogen, or their combination, is less in species-poor than in species-rich regions. In a word, they can raise the carbon density in terrestrial ecosystems by directly or indirectly accelerating net primary production, or constraining respiration and decomposition. However, in spite of its great significance for explaining the present distribution patterns of carbon pools and estimating future changes, the mechanisms by which these processes occur are not fully understood. It is critical that we strengthen our research effort in this area of study. Although a great deal of effort has been put into the carbon density researches, there still remains much uncertainty regarding data collection, mechanistic explanations, and model construction in the relevant studies. In the future, we should establish a standardized and unified system to estimate carbon density, produce more accurate and useful models, and perform integrated studies at multi-scales and multi-resolutions levels.