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首页> 外文期刊>Ecosystems >Holocene Carbon Stocks and Carbon Accumulation Rates Altered in Soils Undergoing Permafrost Thaw
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Holocene Carbon Stocks and Carbon Accumulation Rates Altered in Soils Undergoing Permafrost Thaw

机译：多年冻土融化土壤中全新世碳储量和碳累积速率的变化

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Permafrost soils are a significant global store of carbon (C) with the potential to become a large C source to the atmosphere. Climate change is causing permafrost to thaw, which can affect primary production and decomposition, therefore affecting ecosystem C balance. To understand future responses of permafrost soils to climate change, we inventoried current soil C stocks, investigated ∆14C, C:N, δ13C, and δ15N depth profiles, modeled soil C accumulation rates, and calculated decadal net ecosystem production (NEP) in subarctic tundra soils undergoing minimal, moderate, and extensive permafrost thaw near Eight Mile Lake (EML) in Healy, Alaska. We modeled decadal and millennial soil C inputs, decomposition constants, and C accumulation rates by plotting cumulative C inventories against C ages based on radiocarbon dating of surface and deep soils, respectively. Soil C stocks at EML were substantial, over 50 kg C m−2 in the top meter, and did not differ much among sites. Carbon to nitrogen ratio, δ13C, and δ15N depth profiles indicated most of the decomposition occurred within the organic soil horizon and practically ceased in deeper, frozen horizons. The average C accumulation rate for EML surface soils was 25.8 g C m−2 y−1 and the rate for the deep soil accumulation was 2.3 g C m−2 y−1, indicating these systems have been C sinks throughout the Holocene. Decadal net ecosystem production averaged 14.4 g C m−2 y−1. However, the shape of decadal C accumulation curves, combined with recent annual NEP measurements, indicates soil C accumulation has halted and the ecosystem may be becoming a C source. Thus, the net impact of climate warming on tundra ecosystem C balance includes not only becoming a C source but also the loss of C uptake capacity these systems have provided over the past ten thousand years.
机译：多年冻土是碳的重要全球储存地，有可能成为大气中大量的碳源。气候变化导致永久冻土融化，这可能影响初级生产和分解，从而影响生态系统的碳平衡。为了了解多年冻土对气候变化的未来响应，我们盘点了当前的土壤碳储量，调查了∆14 C，C：N，δ13 C和δ15 N深度剖面，对土壤进行了模拟在阿拉斯加希利的八哩湖（EML）附近经历最小，中度和广泛的多年冻土融化的亚寒带苔原土壤中，碳累积速率和计算的年代际净生态系统产量（NEP）。我们通过基于表层土壤和深层土壤的放射性碳测年绘制累积的C清单对C年龄的图表，对年代和千年土壤C的输入，分解常数和C的累积速率进行了建模。 EML处的土壤碳储量很大，最高米超过50 kg C m-2 ，并且在不同地点之间差异不大。碳氮比，δ13 C和δ15 N深度剖面表明，大部分分解发生在有机土壤层中，而在较深的冻结层中几乎停止了。 EML表层土壤的平均C累积速率为25.8 g C m-2 y-1 ，深层土壤的累积速率为2.3 g C m-2 y-1 < / sup>，表明这些系统在整个全新世都是C汇。十进制生态系统净产量平均为14.4 g C m-2 y-1 。但是，十年碳累积曲线的形状，再加上最近的年度NEP测量，表明土壤碳累积已停止，生态系统可能正在成为碳源。因此，气候变暖对冻原生态系统碳平衡的净影响不仅包括成为碳源，而且还包括这些系统在过去一万年中造成的碳吸收能力的损失。

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