Importance of soil thermal regime in terrestrial ecosystem carbon dynamics in the circumpolar north
Importance of soil thermal regime in terrestrial ecosystem carbon dynamics in the circumpolar north
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DOI：
10.1016/j.gloplacha.2016.04.011
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发表时间：
2016-07
期刊：
影响因子：
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通讯作者：
Yueyang Jiang;Q. Zhuang;S. Sitch;J. O’Donnell;D. Kicklighter;A. Sokolov;J. Melillo
中科院分区：
文献类型：
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作者：
Yueyang Jiang;Q. Zhuang;S. Sitch;J. O’Donnell;D. Kicklighter;A. Sokolov;J. Melillo
在环极北部（45-90°N），多年冻土在植被和碳（C）动态中起着重要作用。气候变暖加速了冻土融化，并通过增加土壤碳释放到大气中对气候产生正反馈作用。为了评估冻土对碳动态的影响，土壤温度剖面的变化应考虑在全球C模式。本研究将一个复杂的土壤热模型（STM）到一个动态的全球植被模型（LPJ-DGVM），以提高土壤温度剖面从地面到3米深的变化模拟，其对C池和通量在20世纪和21世纪的影响。在夏季较冷的模拟土壤温度下，LPJ-STM估计现今异养呼吸比原始LPJ模型低约0.4 Pg C yr− 1，但净初级生产比原始LPJ模型高约0.5 Pg C yr− 1，导致环极生态系统中额外的0.8至1.0 Pg C yr− 1被隔离。在一套预测的变暖情景下，我们表明，增加活动层厚度的结果在动员的永久冻土C，这有助于更快地增加异养呼吸在LPJ-STM相比，独立的LPJ模型。除极端气候变暖条件外，气候变暖和CO2浓度升高导致的植物产量增加，超过了生态系统呼吸作用的增强，使得北方森林和北极苔原生态系统在21世纪世纪仍是碳的净汇。这项研究强调了考虑土壤热制度的变化时，在环极北量化的C预算的重要性。
In the circumpolar north (45–90°N), permafrost plays an important role in vegetation and carbon (C) dynamics. Permafrost thawing has been accelerated by the warming climate and exerts a positive feedback to climate through increasing soil C release to the atmosphere. To evaluate the influence of permafrost on C dynamics, changes in soil temperature profiles should be considered in global C models. This study incorporates a sophisticated soil thermal model (STM) into a dynamic global vegetation model (LPJ-DGVM) to improve simulations of changes in soil temperature profiles from the ground surface to 3 m depth, and its impacts on C pools and fluxes during the 20th and 21st centuries. With cooler simulated soil temperatures during the summer, LPJ-STM estimates ~ 0.4 Pg C yr− 1lower present-day heterotrophic respiration but ~ 0.5 Pg C yr− 1higher net primary production than the original LPJ model resulting in an additional 0.8 to 1.0 Pg C yr− 1being sequestered in circumpolar ecosystems. Under a suite of projected warming scenarios, we show that the increasing active layer thickness results in the mobilization of permafrost C, which contributes to a more rapid increase in heterotrophic respiration in LPJ-STM compared to the stand-alone LPJ model. Except under the extreme warming conditions, increases in plant production due to warming and rising CO2, overwhelm the e nhanced ecosystem respiration so that both boreal forest and arctic tundra ecosystems remain a net C sink over the 21st century. This study highlights the importance of considering changes in the soil thermal regime when quantifying the C budget in the circumpolar north.