Relationship of plant diversity with litter and soil available nitrogen in an alpine meadow under a 9-year grazing exclusion

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• 作者：Jingru Zou ; Caiyun Luo ; Xingliang Xu ; Na Zhao ; Liang Zhao…
• 关键词：Fence ; Functional groups ; Grassland ; Light limitation ; Vegetation
• 刊名：Ecological Research
• 出版年：2016
• 出版时间：November 2016
• 年：2016
• 卷：31
• 期：6
• 页码：841-851
• 全文大小：895 KB
• 刊物主题：Ecology; Plant Sciences; Zoology; Evolutionary Biology; Behavioural Sciences; Forestry;
• 出版者：Springer Japan
• ISSN：1440-1703
• 卷排序：31

文摘

Grazing exclusion is widely used globally to restore degraded grasslands. Plant diversity has important impacts on grassland ecosystem functions, including grassland productivity and carbon storage. In this study, we selected a Kobresia meadow on the Qinghai–Tibetan Plateau to investigate how grazing exclusion affects plant diversity. Inorganic nitrogen (NH₄+ and NO₃−) was also measured because its availability impacts plant growth. We found that plant diversity in the meadow was significantly lower under grazing exclusion (fenced meadow) for 9 years compared with moderate grazing. Accumulated litter was significantly higher under grazing exclusion (386.41 g m−2) compared with grazing (58.77 g m−2). Soil inorganic nitrogen at 0–5 cm depth was significantly higher under grazing exclusion (13.60 × 10−2 g kg−1) than under grazing (9.40 × 10−2 g kg−1). The composition of the four functional groups (grasses, sedges, legumes, and forbs) might alter in response to significant changes in the amount of litter and soil available nitrogen content under grazing exclusion compared with grazing. However, the enhanced soil available nitrogen content showed weak feedbacks on plant diversity. In conclusion, light limitation induced by increased amounts of litter may be the main factor causing decreased plant diversity in grazing-excluded meadows compared with moderately grazed meadows.