The status and stability of permafrost carbon on the Tibetan Plateau
The status and stability of permafrost carbon on the Tibetan Plateau
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DOI：
10.1016/j.earscirev.2020.103433
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发表时间：
2020-12
影响因子：
12.1
通讯作者：
C. Mu;Benjamin W. Abbott;A. J. Norris;Mei Mu;Chenyan Fan;Xu Chen;Lin Jia;Ruimin Yang;
中科院分区：
文献类型：
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作者：
C. Mu;Benjamin W. Abbott;A. J. Norris;Mei Mu;Chenyan Fan;Xu Chen;Lin Jia;Ruimin Yang;
高纬度和高海拔的永久冻土区储存了地球上大约一半的土壤有机碳（SOC）。这些地区也是受人为气候变化影响最严重的地区之一。在此，我们回顾了青藏高原多年冻土的热化学和生物地球化学状况，重点研究了气候变暖下冻土有机碳储量及其脆弱性。青藏高原冻土区土壤有机碳储量在2 m深度为19.0±6.6 Pg。土壤有机碳在TP上的分布与活动层厚度、土壤含水量、土壤质地、地形位置和风化母质厚度密切相关。不同土壤深度和不同土地覆盖类型土壤有机碳分解的平均温度敏感系数（Q10）为9.2±7.1，表明TP上的碳极易受到气候变化的影响。虽然青藏高原生态系统目前是一个净碳汇，但气候变化可能会增加生态系统的呼吸作用，并可能在未来削弱或逆转该地区的碳汇功能。尽管青藏高原的地面冰比高纬度永久冻土区少，但崎岖的地形使其容易受到广泛的永久冻土带崩塌和热侵蚀（热岩溶）的影响，这加速了碳的损失。为了减少有机碳数量的不确定性和对变暖的敏感性，未来需要研究来解释Q10的变化(例如：（基于有机碳来源或沉积位置），量化养分有效性在调节有机碳动态和扰动后生态系统恢复中的作用。此外，在高纬多年冻土区，土壤湿度和热岩溶形成仍然是预测多年冻土区气候对TP反馈的主要挑战。我们提出了一个TP温室气体释放的概念模型，并概述了检验该模型所需的经验观察和建模方法。
Permafrost regions at high latitudes and altitudes store about half of the Earth's soil organic carbon (SOC). These areas are also some of the most intensely affected by anthropogenic climate change. The Tibetan Plateau or Third Pole (TP) contains most of the world's alpine permafrost, yet there remains substantial uncertainty about the role of this region in regulating the overall permafrost climate feedback. Here, we review the thermal and biogeochemical status of permafrost on the TP, with a particular focus on SOC stocks and vulnerability in the face of climate warming. SOC storage in permafrost-affected regions of the TP is estimated to be 19.0±6.6 Pg to a depth of 2 m. The distribution of this SOC on the TP is strongly associated with active layer thickness, soil moisture, soil texture, topographic position, and thickness of weathered parent material. The mean temperature sensitivity coefficient (Q10) of SOC decomposition is 9.2±7.1 across different soil depths and under different land-cover types, suggesting that carbon on the TP is very vulnerable to climate change. While the TP ecosystem currently is a net carbon sink, climate change will likely increase ecosystem respiration and may weaken or reverse the sink function of this region in the future. Although the TP has less ground ice than high latitude permafrost regions, the rugged topography makes it vulnerable to widespread permafrost collapse and thermo-erosion (thermokarst), which accelerates carbon losses. To reduce uncertainty about SOC quantities and sensitivity to warming, future studies are needed that explain variation in Q10(e.g. based on SOC source or depositional position) and quantify the role of nutrient availability in regulating SOC dynamics and ecosystem recovery following disturbance. Additionally, as for the high latitude permafrost region, soil moisture and thermokarst formation remain major challenges to predicting the permafrost climate feedback on the TP. We present a conceptual model for of greenhouse gas release from the TP and outline the empirical observations and modeling approaches needed to test it.