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澳大利亚的生态系统驱动碳吸收

摘要 : 一个国际研究小组的一项研究发现表明,南半球半干旱地区的生物群落未来也许会成为主导性的驱动因素。相关文章发表于2014年5月21日的《Nature》杂志上。

陆地和海洋吸收每年由人类活动造成的碳排放的约一半,彻底了解这一过程对于预测未来温室气体浓度、从而预测气候变化来说很重要。这项研究调查了自从大气CO2测量工作在1958年开始以来对陆地碳的最大吸收。

用于确定全球碳收支的三个独立方法都表明,因应在南半球半干旱地区由拉尼娜现象造成的超乎寻常的降雨,出现了一个特别大的陆地碳汇,其中近60%的碳吸收归因于澳大利亚的生态系统以及大陆净碳吸收对于降水的敏感度的增加。

热带雨林一直被认为主导着驱动全球碳循环年际变化的陆地过程,但这项工作则表明,半干旱生物群落未来也许会成为主导性的驱动因素。

原文摘要:

Contribution of semi-arid ecosystems to interannual variability of the global carbon cycle

Benjamin Poulter, David Frank, Philippe Ciais, Ranga B. Myneni, Niels Andela, Jian Bi,Gregoire Broquet, Josep G. Canadell, Frederic Chevallier, Yi Y. Liu, Steven W. Running,Stephen Sitch & Guido R. van der Werf

The land and ocean act as a sink for fossil-fuel emissions, thereby slowing the rise of atmospheric carbon dioxide concentrations. Although the uptake of carbon by oceanic and terrestrial processes has kept pace with accelerating carbon dioxide emissions until now, atmospheric carbon dioxide concentrations exhibit a large variability on interannual timescales, considered to be driven primarily by terrestrial ecosystem processes dominated by tropical rainforests. We use a terrestrial biogeochemical model, atmospheric carbon dioxide inversion and global carbon budget accounting methods to investigate the evolution of the terrestrial carbon sink over the past 30 years, with a focus on the underlying mechanisms responsible for the exceptionally large land carbon sink reported in 2011 (ref. 2). Here we show that our three terrestrial carbon sink estimates are in good agreement and support the finding of a 2011 record land carbon sink. Surprisingly, we find that the global carbon sink anomaly was driven by growth of semi-arid vegetation in the Southern Hemisphere, with almost 60 per cent of carbon uptake attributed to Australian ecosystems, wher prevalent La Niña conditions caused up to six consecutive seasons of increased precipitation. In addition, since 1981, a six per cent expansion of vegetation cover over Australia was associated with a fourfold increase in the sensitivity of continental net carbon uptake to precipitation. Our findings suggest that the higher turnover rates of carbon pools in semi-arid biomes are an increasingly important driver of global carbon cycle inter-annual variability and that tropical rainforests may become less relevant drivers in the future. More research is needed to identify to what extent the carbon stocks accumulated during wet years are vulnerable to rapid decomposition or loss through fire in subsequent years.

对应Nature杂志: 2014年5月29日Nature杂志精选

来源: Nature中文 浏览次数:28

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