陆地生态系统碳循环研究进展

近年来,碳循环问题日益成为全球变化与地球科学研究领域的前沿与热点问题,其中陆地生态系统碳循环又是全球碳循环中最复杂、受人类活动影响最大的部分。本文结合IGBP和IPCC中有关碳循环的最新报告,介绍了全球碳循环中大气、海洋和陆地生态系统等几个主要碳库的大小及特点,并重点介绍了陆地生态系统碳循环及其基本过程。总结了当前陆地生态系统碳循环研究的四种主要方法:清单方法、反演模拟、涡度相关技术和陆地碳循环模式,介绍了它们的各自特点以及存在的问题,并对陆地碳过程中的不确定性进行了详细分析。此外,还简要叙述了当前碳循环研究中待解决的问题和今后的发展趋势。

Progress in the studies on carbon cycle in terrestrial ecosystem

The concentration of the atmospheric CO_{2, one of the most important greenhouse gases, is increasing since the beginning of industrialization from its pre-industrial value of 280ppmv to its present value of 366ppmv. It has been proved that human activities, including fossil fuel burning, cement production, and land-use change, have severely disrupted the model of the carbon cycle, thereby alter the climate system and affect the processes and mechanisms in terrestrial ecosystems. Understanding the consequences of these changes in the coming decades is critical for the formulation of political, economic, energy, and security policies. So recently,studies in carbon cycle have increasingly become a focus of global change and geo-science in the world. The terrestrial ecosystem,one of the most important parts of the global carbon cycle, is most complex and most greatly affected by human activities. This paper, combined with the latest reports related to carbon cycle in IGBP and IPCC, introduces some major carbon pools, namely, lithosphere, atmosphere, ocean,and terrestrial ecosystem,in the global carbon cycle and their sizes and characteristics. Furthermore, four major approaches, including inventories method, eddy covariance measurements, inverse modeling and model of carbon cycle, which have been used to evaluate the biosphere-atmospheric exchange of CO2in the terrestrial ecosystems,are introduced. Using inventories method we can get an estimate of the actual accumulation of carbon in terrestrial ecosystem. The eddy covariance approach can detect small changes in net CO2exchange between terrestrial ecosystems and the atmosphere over various time scales. Inverse modeling approach can be used to infer carbon sources or sinks based on 3-D atmospheric tracer transport models and CO2 records from the atmospheric observations, fossil fuel combustion and land use change. Model of carbon cycle is a powerful tool to estimate and evaluate the temporal and spatial patterns of carbon sources or sinks in various scales. The existing problems of using these four methods are also analyzed. Moreover, the uncertainties in terrestrial carbon process are analyzed particularly.Additionally,some problems unsettled in carbon cycle and development tendency are specified concisely.}