Key Laboratory of Adaptation and Evolution of Plateau Biota, Northwest Plateau Institute of Biology, Chinese Academy of Sciences, Xinning Road 31, Xining 810008, China.
University of Chinese Academy of Sciences, Beijing 100049, China.
Sci Rep. 2017 Jan 9;7:40307. doi: 10.1038/srep40307.
Artificial grasslands play a role in carbon storage on the Qinghai-Tibetan Plateau. The artificial grasslands exhibit decreased proportions of graminate and increased species richness with age. However, the effect of the graminate proportions and species richness on ecosystem C stocks in artificial grasslands have not been elucidated. We conducted an in situC pulse-labeling experiment in August 2012 using artificial grasslands that had been established for two years (2Y), five years (5Y), and twelve years (12Y). Each region was plowed fallow from severely degraded alpine meadow in the Qinghai-Tibetan Plateau. The 12Y grassland had moderate proportions of graminate and the highest species richness. This region showed more recovered C in soil and a longer mean residence time, which suggests species richness controls the ecosystem C stock. The loss rate of leaf-assimilated C of the graminate-dominant plant species Elymus nutans in artificial grasslands of different ages was lowest in the 12Y grassland, which also had the highest species richness. Thus the lower loss rate of leaf-assimilated C can be partially responsible for the larger ecosystem carbon stocks in the 12Y grassland. This finding is a novel mechanism for the effects of species richness on the increase in ecosystem functioning.
人工草地在青藏高原的碳存储中发挥作用。人工草地的禾本科植物比例随年龄的增加而减少，而物种丰富度则增加。然而，禾本科植物比例和物种丰富度对人工草地生态系统碳储量的影响尚未阐明。我们于 2012 年 8 月在青藏高原严重退化高寒草甸开垦的两年（2Y）、五年（5Y）和十二年（12Y）的人工草地中进行了原位 C 脉冲标记实验。12Y 草地的禾本科植物比例适中，物种丰富度最高。该地区土壤中 C 恢复量更多，平均停留时间更长，这表明物种丰富度控制着生态系统的碳储量。不同年龄人工草地中禾本科优势植物垂穗披碱草叶片同化 C 的损失率在 12Y 草地中最低，该地区的物种丰富度也最高。因此，叶片同化 C 的较低损失率可能部分解释了 12Y 草地具有更大的生态系统碳储量的原因。这一发现为物种丰富度对生态系统功能增强的影响提供了一个新的机制。
