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| 施肥和放牧对青藏高原高寒草甸物种丰富度的影响 | |
| 引用本文： | 杨中领,苏芳龙,苗原,钟明星,肖蕊. 施肥和放牧对青藏高原高寒草甸物种丰富度的影响[J]. 植物生态学报, 2014, 38(10): 1074-1081. DOI: 10.3724/SP.J.1258.2014.00101 |
| 作者姓名： | 杨中领 苏芳龙 苗原 钟明星 肖蕊 |
| 作者单位： | 河南大学生命科学学院, 河南开封 475000 南京农业大学资源与环境科学学院, 南京 210000 |
| 基金项目： | 种子限制和幼苗定居限制在物种循环过程中的作用;种子在中国北方温带草原群落构建过程中的作用 |
| 摘 要： | 在草地生态系统中, 施肥通常会导致生物多样性下降, 但是关于引起生物多样性下降的机制还存在着很大的争议。该研究基于一个4年的施肥实验, 试图通过个体大小的不整齐性和单位植物氮含量, 定性地揭示青藏高原东部高寒草甸施肥后多样性下降的原因。研究显示: 在封育地, 施肥致使个体大小不整齐性增加了15%, 并不同程度地增加了物种的高度。同时, 施肥使物种间单位植物氮含量存在显著差异的数目降低了65%。施肥后光竞争加剧, 导致大个体植物排斥小个体植物, 进而引起了物种丰富度下降29.6%。与封育地不同, 放牧地施肥并没有改变个体大小不整齐性和物种的高度, 而是使物种间单位植物氮含量存在显著差异的数目增加了11.4%。施肥并没有改变放牧地的光竞争强度, 而是增加了物种间对土壤营养元素氮的竞争强度, 进而引起了物种丰富度下降17.3%。该研究还发现, 放牧施肥地的物种丰富度下降速度和等级显著低于封育施肥地的物种丰富度下降速度和等级, 这表明放牧减缓了施肥对物种丰富度的影响力。 |
| 关 键 词： | 高寒草甸 地下竞争 群落生态学 光竞争 大小不整齐性 物种丰富度 |
| 收稿时间： | 2014-01-28 |
| 修稿时间： | 2014-09-24 |
Effects of fertilization and grazing on species richness in an alpine meadow of Qinghai-Xizang Plateau |
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| YANG Zhong-Ling,SU Fang-Long,MIAO Yuan,ZHONG Ming-Xing,XIAO Rui. Effects of fertilization and grazing on species richness in an alpine meadow of Qinghai-Xizang Plateau[J]. Acta Phytoecologica Sinica, 2014, 38(10): 1074-1081. DOI: 10.3724/SP.J.1258.2014.00101 | |
| Authors: | YANG Zhong-Ling SU Fang-Long MIAO Yuan ZHONG Ming-Xing XIAO Rui |
| Affiliation: | School of Life Science, Henan University, Kaifeng, Henan 475000, China College of Resources and Environmental Science, Nanjing Agricultural University, Nanjing 210000, China |
| Abstract: | Aims Plant species diversity often declines when nutrients are added in grassland. However, the mechanisms for explaining biodiversity loss due to nutrient enrichment have remained controversial. Our objective was to explore the potential mechanisms of diversity decline. Methods In this paper, based on a four-year experiment of nutrient addition and grazing in an alpine plant community, we investigate the potential mechanisms of diversity loss by comparing the above- and below-ground competitions using coefficient of variation and nitrogen use efficiency under fertilization scenario both in grazed and non-grazed plots. Important findings Fertilization increased the size inequality of individuals by 15%, increased species height by different degrees, and reduced the number of species pairs that differed significantly in nitrogen content by 65% in the non-grazed plots. The results indicate that the large-sized individuals out-competed the small-sized individuals due to competition for light, which led to a decline in species richness by 29.6% in the non-grazed plots following fertilization. In contrast, fertilization did not change the size inequality of individuals and species height in the grazed plots, and increased the number of species pairs that differed significantly in nitrogen content by 11.4%, implying that an increased competition for soil nitrogen among species reduced the species richness by 17.3%. Our study also suggests that grazing delayed the effect of fertilization on species richness as inferred by the lower rate of species loss in the grazed plots. |
| Keywords: | alpine meadow belowground competition community ecology light competition size inequality species richness |
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