Nutrient addition prompts rapid destabilization of organic matter in an arctic tundra ecosystem
Nutrient addition prompts rapid destabilization of organic matter in an arctic tundra ecosystem
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DOI：
10.1007/s10021-007-9104-1
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发表时间：
2008-02-01
期刊：
影响因子：
3.7
通讯作者：
Shaver, Gaius R.
中科院分区：
文献类型：
--
作者：
Nowinski, Nicole S.;Trumbore, Susan E.;Shaver, Gaius R.
由于与变暖相关的加速分解，北极地区的养分供应预计将在下个世纪增加，在较小程度上，增加氮沉积。为了探索养分供应的变化如何影响生态系统碳（C）循环，我们使用放射性碳来量化与阿拉斯加图里克湖禾本科植物为主的草丛苔原长期施肥相关的地下C动态变化。自1981年以来，每年施肥与氮（N）和磷（P）已导致转向灌木为主的植被。这些变化改变了凋落物输入的数量和质量、细根的垂直分布和动态以及土壤有机C的分解速率。深层有机和矿物质土壤中C的损失远远抵消了枯枝落叶层和上层有机土壤层中C的积累。在凋落物和上层有机层，放射性碳测量表明，增加投入导致整体C积累，尽管被抵消了一些土壤池的分解增加。为了调和放射性碳观测在更深的有机和矿物土壤层，其中大部分的生态系统C的损失发生，既减少了新的根材料的输入和急剧增加的分解率在几个世纪的土壤C池。因此，随着未来养分可利用性的增加，我们可能会预计到碳的大量损失，而碳的损失是经过几个世纪的积累才积累起来的。
Nutrient availability in the arctic is expected to increase in the next century due to accelerated decomposition associated with warming and, to a lesser extent, increased nitrogen deposition. To explore how changes in nutrient availability affect ecosystem carbon (C) cycling, we used radiocarbon to quantify changes in belowground C dynamics associated with long-term fertilization of graminoid-dominated tussock tundra at Toolik Lake, Alaska. Since 1981, yearly fertilization with nitrogen (N) and phosphorus (P) has resulted in a shift to shrub-dominated vegetation. These combined changes have altered the quantity and quality of litter inputs, the vertical distribution and dynamics of fine roots, and the decomposition rate of soil organic C. The loss of C from the deep organic and mineral soil has more than offset the C accumulation in the litter and upper organic soil horizons. In the litter and upper organic horizons, radiocarbon measurements show that increased inputs resulted in overall C accumulation, despite being offset by increased decomposition in some soil pools. To reconcile radiocarbon observations in the deeper organic and mineral soil layers, where most of the ecosystem C loss occurred, both a decrease in input of new root material and a dramatic increase of decomposition rates in centuries-old soil C pools were required. Therefore, with future increases in nutrient availability, we may expect substantial losses of C which took centuries to accumulate.