A potential loss of carbon associated with greater plant growth in the European Arctic
A potential loss of carbon associated with greater plant growth in the European Arctic
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DOI：
10.1038/nclimate1575
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发表时间：
2012-12-01
影响因子：
30.7
通讯作者：
Wookey, Philip A.
中科院分区：
文献类型：
--
作者：
Hartley, Iain P.;Garnett, Mark H.;Wookey, Philip A.
快速变暖预计将增加北极地区的植物生长(1)，并导致树木逐渐在冻土带定居(2)。模型预测，增加植物生物量中的碳(C)储存可能有助于抵消大气中二氧化碳的增加，并降低气候变化的速度(2-4)。然而，在一些北极生态系统中，高植物生产力与土壤碳的快速循环和低储量有关(参考文献1、5、6)；因此，随着植物生长的增加，土壤碳可能会通过加强分解而损失。在这里，我们表明，在瑞典北部，苔原荒漠(由于土壤碳储量较大)的总生态系统碳储量比生产力更高的山桦林更大。此外，我们还证明，在森林中，生长季节中期的高植物活动会刺激较老的土壤有机质的分解。这种被称为正启动的反应有助于解释为什么与冻土带相比，森林中的土壤碳储量较低。我们认为，随着更多生产力的森林群落定居冻土带，冻土带土壤中大量碳库的分解可能会受到刺激。因此，与直觉相反的是，欧洲北极地区植物生长的增加可能导致碳被释放到大气中，从而加速气候变化。
Rapid warming is expected to increase plant growth in the Arctic(1), and result in trees gradually colonizing tundra(2). Models predict that enhanced carbon (C) storage in plant biomass may help offset atmospheric CO2 increases and reduce rates of climate change(2-4). However, in some Arctic ecosystems, high plant productivity is associated with rapid cycling and low storage of soil C (refs 1,5,6); thus, as plant growth increases, soil C may be lost through enhanced decomposition. Here we show that, in northern Sweden, total ecosystem C storage is greater in tundra heath (owing to greater soil C stocks) than in more productive mountain-birch forest. Furthermore, we demonstrate that in the forest, high plant activity during the middle of the growing season stimulates the decomposition of older soil organic matter. Such a response, referred to as positive priming, helps explain the low soil C storage in the forest when compared with the tundra. We suggest that, as more productive forest communities colonize tundra, the decomposition of the large C stocks in tundra soils could be stimulated. Thus, counter-intuitively, increased plant growth in the European Arctic could result in C being released to the atmosphere, accelerating climate change.