Millennial-scale hydroclimate control of tropical soil carbon storage
Millennial-scale hydroclimate control of tropical soil carbon storage
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DOI：
10.1038/s41586-020-2233-9
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发表时间：
2020-05-01
期刊：
影响因子：
64.8
通讯作者：
Galy, Valier V.
中科院分区：
文献类型：
--
作者：
Hein, Christopher J.;Usman, Muhammed;Galy, Valier V.
在过去的18000年里，恒河-雅鲁藏布江盆地的土壤碳储存时间和储存量受到印度夏季季风降雨强度的控制，在潮湿、温暖的条件下，碳的不稳定程度更大。陆地生物圈中有机碳的储存在很宽的时间尺度上直接影响大气中二氧化碳的浓度。在陆地生物圈内，碳储存量可能会因温度或水文气候变化等环境扰动而变化(1)，从而可能产生有关大气二氧化碳库存的反馈。尽管温度控制中高纬度地区土壤有机碳的储存(2,3)，但水文气候可能是热带地区土壤碳持久性的主要驱动因素(4,5)；然而，热带土壤碳周转对大规模水文气候变化的敏感性仍然知之甚少。在这里，我们发现印度夏季季风降雨的变化控制了过去 18,000 年来恒河-雅鲁藏布江盆地土壤碳的停留时间。将大量有机碳和陆地高等植物生物标志物的放射性碳年龄与同一地点的古水文记录进行比较(6)，揭示了在千年时间尺度上季风降雨与土壤有机碳储量之间的负相关关系。在整个冰消期，降雨量增加和相关的土壤呼吸速率增强引发了全流域土壤碳储量的消耗。我们的研究结果表明，热带地区未来的水文气候变化可能会加速土壤碳的不稳定，进一步增加大气中二氧化碳的浓度。
Over the past 18,000 years, the residence time and amount of soil carbon stored in the Ganges-Brahmaputra basin have been controlled by the intensity of Indian Summer Monsoon rainfall, with greater carbon destabilization during wetter, warmer conditions.The storage of organic carbon in the terrestrial biosphere directly affects atmospheric concentrations of carbon dioxide over a wide range of timescales. Within the terrestrial biosphere, the magnitude of carbon storage can vary in response to environmental perturbations such as changing temperature or hydroclimate(1), potentially generating feedback on the atmospheric inventory of carbon dioxide. Although temperature controls the storage of soil organic carbon at mid and high latitudes(2,3), hydroclimate may be the dominant driver of soil carbon persistence in the tropics(4,5); however, the sensitivity of tropical soil carbon turnover to large-scale hydroclimate variability remains poorly understood. Here we show that changes in Indian Summer Monsoon rainfall have controlled the residence time of soil carbon in the Ganges-Brahmaputra basin over the past 18,000 years. Comparison of radiocarbon ages of bulk organic carbon and terrestrial higher-plant biomarkers with co-located palaeohydrological records(6) reveals a negative relationship between monsoon rainfall and soil organic carbon stocks on a millennial timescale. Across the deglaciation period, a depletion of basin-wide soil carbon stocks was triggered by increasing rainfall and associated enhanced soil respiration rates. Our results suggest that future hydroclimate changes in tropical regions are likely to accelerate soil carbon destabilization, further increasing atmospheric carbon dioxide concentrations.