Atmosphere-soil carbon transfer as a function of soil depth
Atmosphere-soil carbon transfer as a function of soil depth
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DOI：
10.1038/s41586-018-0328-3
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发表时间：
2018-07-26
期刊：
影响因子：
64.8
通讯作者：
Hatte, Christine
中科院分区：
文献类型：
--
作者：
Balesdent, Jerome;Basile-Doelsch, Isabelle;Hatte, Christine
土壤有机碳（SOC）和大气之间的碳交换影响气候（1，2），并且由于有机物质对土壤肥力的重要性，影响农业生产力（3）。表层土壤碳的动态已经相对较好地量化（4），但土壤碳的一半位于较深的土壤层（30厘米以下）（5-7），关于这种深层碳与大气的交换仍然存在许多问题（8）。这种知识差距限制了土壤碳管理政策，并限制了全球碳模型（1，9，10）。在这里，我们通过对1965年至2015年不同气候带112个草原，森林和农田站点的稳定碳同位素特征变化的荟萃分析，量化了最近将大气来源的碳原子纳入全土壤剖面。我们发现，与以前的工作（5，6）一致，在地表以下30-100厘米深处的土壤（底土）平均含有47%的最高米的SOC库存。然而，我们发现，这种底土仅占最近（在过去50年内）纳入最顶层米的SOC的19%。在全球范围内，最近碳进入矿物质土壤的深度中值为10厘米。干旱指数比年平均气温更能解释深层土壤碳相对分配的变化。土地用于种植作物减少了碳进入土壤表层，但不会进入深层。我们的研究结果表明，SOC动态及其对气候控制或土地利用的响应强烈依赖于土壤深度。我们建议在全球碳模型中使用多层土壤模块，并使用我们的数据进行测试，可以帮助提高我们对土壤-大气碳交换的理解。
The exchange of carbon between soil organic carbon (SOC) and the atmosphere affects the climate(1,2) and-because of the importance of organic matter to soil fertility-agricultural productivity(3). The dynamics of topsoil carbon has been relatively well quantified(4), but half of the soil carbon is located in deeper soil layers (below 30 centimetres)(5-7), and many questions remain regarding the exchange of this deep carbon with the atmosphere(8). This knowledge gap restricts soil carbon management policies and limits global carbon models(1,9,10). Here we quantify the recent incorporation of atmosphere-derived carbon atoms into whole-soil profiles, through a meta-analysis of changes in stable carbon isotope signatures at 112 grassland, forest and cropland sites, across different climatic zones, from 1965 to 2015. We find, in agreement with previous work(5,6), that soil at a depth of 30-100 centimetres beneath the surface (the subsoil) contains on average 47 per cent of the topmost metre's SOC stocks. However, we show that this subsoil accounts for just 19 per cent of the SOC that has been recently incorporated (within the past 50 years) into the topmost metre. Globally, the median depth of recent carbon incorporation into mineral soil is 10 centimetres. Variations in the relative allocation of carbon to deep soil layers are better explained by the aridity index than by mean annual temperature. Land use for crops reduces the incorporation of carbon into the soil surface layer, but not into deeper layers. Our results suggest that SOC dynamics and its responses to climatic control or land use are strongly dependent on soil depth. We propose that using multilayer soil modules in global carbon models, tested with our data, could help to improve our understanding of soil-atmosphere carbon exchange.