Interannual variability in responses of belowground net primary productivity (NPP) and NPP partitioning to long-term warming and clipping in a tallgrass prairie
Interannual variability in responses of belowground net primary productivity (NPP) and NPP partitioning to long-term warming and clipping in a tallgrass prairie
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DOI：
10.1111/j.1365-2486.2012.02651.x
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发表时间：
2012-05-01
影响因子：
11.6
通讯作者：
Luo, Yiqi
中科院分区：
文献类型：
--
作者：
Xu, Xia;Niu, Shuli;Luo, Yiqi
草地地下净初级生产力（BNPP）的动态变化对了解草地碳（C）的分配和储量具有重要意义。然而，我们的知识的年际变化的响应BNPP持续的全球变暖是有限的。在这项研究中，我们探讨了在美国俄克拉荷马州的高草草原的BNPP和净初级生产力（NPP）分配的时间响应变暖和修剪。自1999年11月以来，使用红外线加热器将土壤温度提高了约2摄氏度。每年修剪是为了模仿干草收获。2005 - 2009年，气候变暖使未修剪子样地的BNPP平均增加41.89%，使修剪子样地的BNPP平均增加66.93%，其中丰水年的BNPP显著增加。削减对BNPP也有显著的正影响，主要是在变暖的情况下。总体而言，fBNPP，即BNPP占NPP的比例，在变暖和修剪处理下都有所增加，在干旱年份更多。水的供应（无论是降水或土壤水分）是最限制因素的BNPP和fBNPP。在NPP、fBNPP的年际变化及其对增温和削波的响应中，它起着重要的主导作用。我们的研究结果表明，水的可用性调节高草草原的气候变暖和土地利用变化的反应，这可能最终影响全球碳循环。随着未来降水模式的变化越来越大，对该地区植被的变暖影响可能变得更难以预测。
The dynamics of belowground net primary productivity (BNPP) is of fundamental importance in understanding carbon (C) allocation and storage in grasslands. However, our knowledge of the interannual variability in response of BNPP to ongoing global warming is limited. In this study, we explored temporal responses of BNPP and net primary productivity (NPP) partitioning to warming and clipping in a tallgrass prairie in Oklahoma, USA. Infrared heaters were used to elevate soil temperature by approximately 2 degrees C since November 1999. Annual clipping was to mimic hay harvest. On average from 2005 to 2009, warming increased BNPP by 41.89% in the unclipped subplots and 66.93% in the clipped subplots, with significant increase observed in wet years. Clipping also had significant positive impact on BNPP, which was mostly found under warming. Overall, fBNPP, the fraction of BNPP to NPP, increased under both warming and clipping treatments, more in dry years. Water availability (either precipitation or soil moisture) was the most limiting factor for both BNPP and fBNPP. It strongly dominated the interannual variability in NPP, fBNPP, and their responses to warming and clipping. Our results suggest that water availability regulates tallgrass prairie's responses to warming and land use change, which may eventually influence the global C cycle. With increasing variability in future precipitation patterns, warming effects on the vegetation in this region may become less predictable.