Recent patterns and mechanisms of carbon exchange by terrestrial ecosystems
Recent patterns and mechanisms of carbon exchange by terrestrial ecosystems
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DOI：
10.1038/35102500
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发表时间：
2001-11-08
期刊：
影响因子：
64.8
通讯作者：
Wirth, C
中科院分区：
文献类型：
--
作者：
Schimel, DS;House, JI;Wirth, C
了解大气、陆地和海洋之间的碳交换十分重要，因为陆地和海洋环境目前吸收了化石燃料燃烧所排放的二氧化碳的大约一半。因此，这种碳吸收限制了大气和气候变化的程度，但其长期性质仍然不确定。在这里，我们提供了一个由陆地生态系统的碳交换的全球和区域模式的知识现状的概述。大气中二氧化碳和氧气的数据证实，陆地生物圈在1980年代的净碳交换方面基本上是中性的，但在1990年代成为净碳汇。这种近期的下沉可以在很大程度上归因于北方的温带地区，大致分为北美和欧亚大陆。然而，热带陆地地区的碳交换大致平衡，这意味着碳汇抵消了热带毁林造成的排放。陆地碳汇的演变在很大程度上是土地利用随时间变化的结果，如废弃农田的再生和防火，此外还有对环境变化的反应，如生长季节的延长以及二氧化碳和氮的施肥。然而，在不同区域的汇的规模和不同过程的贡献方面仍然存在着相当大的不确定性。
Knowledge of carbon exchange between the atmosphere, land and the oceans is important, given that the terrestrial and marine environments are currently absorbing about half of the carbon dioxide that is emitted by fossil-fuel combustion. This carbon uptake is therefore limiting the extent of atmospheric and climatic change, but its long-term nature remains uncertain. Here we provide an overview of the current state of knowledge of global and regional patterns of carbon exchange by terrestrial ecosystems. Atmospheric carbon dioxide and oxygen data confirm that the terrestrial biosphere was largely neutral with respect to net carbon exchange during the 1980s, but became a net carbon sink in the 1990s. This recent sink can be largely attributed to northern extratropical areas, and is roughly split between North America and Eurasia. Tropical land areas, however, were approximately in balance with respect to carbon exchange, implying a carbon sink that offset emissions due to tropical deforestation. The evolution of the terrestrial carbon sink is largely the result of changes in land use over time, such as regrowth on abandoned agricultural land and fire prevention, in addition to responses to environmental changes, such as longer growing seasons, and fertilization by carbon dioxide and nitrogen. Nevertheless, there remain considerable uncertainties as to the magnitude of the sink in different regions and the contribution of different processes.