Primary production and rain use efficiency across a precipitation gradient on the Mongolia plateau
Primary production and rain use efficiency across a precipitation gradient on the Mongolia plateau
复制标题
蒙古高原不同降水梯度的初级生产和雨水利用效率
DOI：
10.1890/07-0992.1
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发表时间：
2008-08-01
期刊：
影响因子：
4.8
通讯作者：
Han, Xingguo
中科院分区：
文献类型：
--
作者：
Bai, Yongfei;Wu, Jianguo;Han, Xingguo
了解全球干旱和半干旱生态系统的地上净初级生产量（ANPP）如何响应降水变化，对于评估气候变化对陆地生态系统的影响至关重要。雨水利用效率（RUE）是获得这一认识的重要指标。然而，对于世界上最大的连续天然草原区欧亚草原，RUE的响应模式知之甚少。基于内蒙古草原地区21个自然干旱区和半干旱区生态系统样点的长期数据，研究了ANPP和RUE的时空格局及其关键驱动因子。结果表明，随着年平均降水量（MAP）的增加，(1)ANPP增加，而ANPP的年际变率下降；(2)植物物种丰富度增加，关键功能群的相对丰度发生可预测的变化；(3)同一生态系统内，不同生态系统间的RUE空间增加，但随着年平均降水量的增加而减少。这些结果清楚地表明，ANPP和RUE的模式都是尺度依赖的，而RUE在空间和时间上看似冲突的模式表明了不同的潜在机制，涉及降水、土壤氮和生物因子之间的相互作用。此外，虽然我们的结果支持存在一个共同的最大RUE，但它们也表明，通过改变资源可用性，例如添加氮，它的值可以大大增加。研究结果对于理解和预测全球气候变化对生态系统的影响，以及内蒙古草原地区干旱和半干旱生态系统的管理实践具有重要意义。
Understanding how the aboveground net primary production (ANPP) of arid and semiarid ecosystems of the world responds to variations in precipitation is crucial for assessing the impacts of climate change on terrestrial ecosystems. Rain-use efficiency (RUE) is an important measure for acquiring this understanding. However, little is known about the response pattern of RUE for the largest contiguous natural grassland region of the world, the Eurasian Steppe. Here we investigated the spatial and temporal patterns of ANPP and RUE and their key driving factors based on a long-term data set from 21 natural arid and semiarid ecosystem sites across the Inner Mongolia steppe region in northern China. Our results showed that, with increasing mean annual precipitation (MAP), (1) ANPP increased while the interannual variability of ANPP declined, (2) plant species richness increased and the relative abundance of key functional groups shifted predictably, and (3) RUE increased in space across different ecosystems but decreased with increasing annual precipitation within a given ecosystem. These results clearly indicate that the patterns of both ANPP and RUE are scale dependent, and the seemingly conflicting patterns of RUE in space vs. time suggest distinctive underlying mechanisms, involving interactions among precipitation, soil N, and biotic factors. Also, while our results supported the existence of a common maximum RUE, they also indicated that its value could be substantially increased by altering resource availability, such as adding nitrogen. Our findings have important implications for understanding and predicting ecological impacts of global climate change and for management practices in arid and semiarid ecosystems in the Inner Mongolia steppe region and beyond.