Globally rising soil heterotrophic respiration over recent decades
Globally rising soil heterotrophic respiration over recent decades
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DOI：
10.1038/s41586-018-0358-x
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发表时间：
2018-08-02
期刊：
影响因子：
64.8
通讯作者：
Vargas, Rodrigo
中科院分区：
文献类型：
--
作者：
Bond-Lamberty, Ben;Bailey, Vanessa L.;Vargas, Rodrigo
全球土壤储存的碳至少是地球大气的两倍（1,2）。全球土壤到大气（或总土壤呼吸，R-S）二氧化碳（CO2）通量正在增加（3,4），但由于异养呼吸（R-H），气候变化将在多大程度上刺激土壤中的碳损失仍然高度不确定（5-8）。本研究使用更新的全球土壤呼吸数据库(9)显示，观测到的土壤表面R-H:R-S比值在1990年至2014年间显著增加，从0.54增加到0.63 （P = 0.009）。另外有三条证据支持这一发现。通过分析两个独立的全球初级生产总值数据集（10,11），我们发现R-H和R-S占初级生产总值的比例随着时间的推移而增加。同样，通过最长可用的太阳诱导叶绿素荧光全球数据集，以及通过全球陆地模式集合计算的初级总产量，也观察到R-H的显著增加。我们还表明，夜间净生态系统交换与初级生产总值的比例在FLUXNET2015（12）数据集中呈上升趋势。所有趋势对生态系统类型、干扰、方法、CO2施肥效应和平均气候的采样变异性都是稳健的。综上所述，我们的研究结果提供了观测证据，表明全球R-H正在上升，这可能是对环境变化的反应，与荟萃分析（13-16）和长期实验（17）一致。这表明，气候驱动的土壤碳损失目前正在许多生态系统中发生，并在全球范围内出现了可检测和持续的趋势。
Global soils store at least twice as much carbon as Earth's atmosphere(1,2). The global soil-to-atmosphere (or total soil respiration, R-S) carbon dioxide (CO2) flux is increasing(3,4), but the degree to which climate change will stimulate carbon losses from soils as a result of heterotrophic respiration (R-H) remains highly uncertain(5-8). Here we use an updated global soil respiration database(9) to show that the observed soil surface R-H:R-S ratio increased significantly, from 0.54 to 0.63, between 1990 and 2014 (P = 0.009). Three additional lines of evidence provide support for this finding. By analysing two separate global gross primary production datasets(10,11), we find that the ratios of both R-H and R-S to gross primary production have increased over time. Similarly, significant increases in R-H are observed against the longest available solar-induced chlorophyll fluorescence global dataset, as well as gross primary production computed by an ensemble of global land models. We also show that the ratio of night-time net ecosystem exchange to gross primary production is rising across the FLUXNET2015(12) dataset. All trends are robust to sampling variability in ecosystem type, disturbance, methodology, CO2 fertilization effects and mean climate. Taken together, our findings provide observational evidence that global R-H is rising, probably in response to environmental changes, consistent with metaanalyses(13-16) and long-term experiments(17). This suggests that climate-driven losses of soil carbon are currently occurring across many ecosystems, with a detectable and sustained trend emerging at the global scale.