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Plant traits and soil properties in pasture mini-patches in an alpine meadow
- SHI Ming-Ming, ZHANG Yong-Chao, ZHANG Dian-Ye, REN Yun-Tao, ZONG Wen-Jie, FU Hua, NIU De-Cao
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2015, 24(9):
197-205.
DOI: 10.11686/cyxb2015083
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The patchiness and persistence of plant communities represent grassland responses to outside disturbance, and are the basis of sustainable development of plant communities and biodiversity. The aim of this study was to understand the factors contributing to the maintenance and development of plant communities and the effects of patchiness on soil properties after a disturbance. The changes in the types, number, and areas of mini-patches in meadows were evaluated in meadows with a light, moderate, and heavy density of plateau pika (Ochotona curzoniae) burrows. The plant community structure and soil properties were evaluated for five types of patches in meadows with a moderate number of burrows. Some mini-patches were characterized by a high abundance of a single species, with mini-patch areas ranging from 0.5 m2 to 100 m2 in an alpine meadow (not including background patches). These types of patches were named according to the main plant species. We chose three approximately 1-hectare sample sites with different burrow densities; light, moderate, and heavy. Three quadrats (20 m×20 m) were placed randomly to determine the types, number, and area of patches within each site. We chose five types of patches from the three sample sites, and selected three typical patches for each type to determine the plant community structure and soil properties. Quadrat sampling (1 m×1 m) was used to determine basic plant traits (composition, height, cover degree, above-ground biomass of vegetation) and soil properties (organic carbon, pH, total nitrogen, available nitrogen, total phosphorus, available phosphorus) in the patches. The meadows with moderate burrow density had the most types of patches and the greatest abundance of patches. The total area of patches tended to increase with greater deterioration caused by plateau pika. The number and areas of Potentilla anserine, Ligularia virgaurea, and Anemone rivularis patches tended to increase, and their areas increased dramatically from the moderate to heavy burrow density. The number and areas of Anaphalis lacteal and Leontopodium japonicum patches tended to decrease, and these patches tend to disappear from as the burrow density increased from moderate to heavy. There were few main types of pasture mini-patches, and the pattern of patches was relatively simple under heavy burrow density. An abnormal increase in the biomass of a single species was the main characteristic of the patches. The expanding propagation of single species affected the structures of plant functional groups and species abundance, and thus, cushioned the effects of other types of disturbance. The results of the principal component analysis showed that the amounts of total nitrogen, available nitrogen, and available phosphorus in soil were lower in four types of patches than in A. lacteal patches and background patches. The coefficients of variation were higher for soil total nitrogen, available nitrogen, and available phosphorus than for other soil properties in patches in the meadows with moderate burrow density. The contents and spatial heterogeneity of soil total nitrogen, available nitrogen, and available phosphorus were more sensitive than the responses of vegetation succession to plateau pika activity. Therefore, it is very important that the supply of total nitrogen and available nutrients are maintained to retain the stability of the alpine meadow ecosystem.