Abstract: 【Objective】 To study changes of plant community in mountain meadow grassland under different grazing intensities in the hope of providing scientific basis for rational utilization of this kind of grassland.【Method】 From 2016 to 2018, for three consecutive years, field sampling and indoor analysis were used to analyze the quantitative characteristics, diversity index and the relationship between diversity index and aboveground biomass of mountainous meadow grassland in the middle part of the northern slope of Tianshan Mountain. The quantitative characteristics, diversity index and the relationship between the diversity index and the above-ground biomass were analyzed by light grazing (LG), heavy grazing (HG) and non-grazing control (CK). 【Result】 (1) Under different grazing intensities, perennial herbs were dominant in mountain meadow, and the dominant species were Carex stenocarpa, Koeleria cristata, Stipa capillata and Achnatherum inebrians. Under the condition of heavy grazing (HG), livestock firstly adopted plants with good palatability, and the number of plants with good palatability in the community decreased, and the dominant position of the community was gradually replaced by poisonous plants such as A. inebrians. (2) Under CK and light grazing (LG) and heavy grazing (HG) conditions, with the increase of grazing intensity, above-ground biomass, height and coverage of plant communities showed a decreasing trend from 2016 to 2018 (P<0.05). The community density showed a decreasing trend from 2016 to 2017 (P<0.05). (3) With the increase of grazing intensity, the Shannon-Wiener diversity index, Simpson index and Pielou evenness index of plant community species all declined, showing CK > LG > HG. There was no significant difference between CK, LG and HG from 2016 to 2017 (P> 0.05), while there was significant difference between CK, LG and HG in 2018 (P< 0.05). (4) There was a positive linear correlation between Pielou index, Shannon-Wiener index, ,Margalef index, aboveground biomass under LG, HG and CK conditions (P<0.05).【Conclusion 】 Under different grazing intensities, the Simpson index, Pielouindex and Shannon-Wiener index of plant communities in mountain meadow decreased with increase of grazing intensities. There was a significant positive linear correlation between aboveground biomass and Pielou evenness index, Shannon-Wiener diversity index and Margalef index (P<0.05).

Key words: mountain meadow grassland; grazing intensity; plant diversity; above-ground biomass; correlation

摘要： 【目的】 研究不同放牧强度下,山地草甸草地植物群落变化,为合理利用该类草地提供科学依据。【方法】 2016~2018年连续3年采用野外取样和室内分析相结合的方法,以天山北坡中段山地草甸草地为研究对象,设置轻度放牧(LG)、重度放牧(HG)和无放牧对照(CK),分析山地草甸草地植物群落数量特征、多样性指数,以及多样性指数与地上生物量间的关系。【结果】 (1)不同放牧强度下山地草甸草地以多年生草本植物为绝对优势,主要优势种有细果苔草(Carex stenocarpa)、溚草(Koeleria cristata)、针茅(Stipa capillata)、醉马草(Achnatherum inebrians);在重度放牧(HG)条件下,家畜首先采食适口性较好的植物,群落中适口性好的植物数量减少,群落优势地位逐步被有毒植物醉马草所替代。(2)CK与LG、HG条件下,随着放牧强度的增加,2016~2018年间植物群落地上生物量、群落高度和盖度呈下降趋势(P<0.05);群落密度在2016~2017年间呈下降趋势(P<0.05)。(3)随着放牧强度的增加,植物群落物种Shannon-Wiener多样性指数、Simpson优势度指数和Pielou均匀度指数均下降趋势,表现为CK＞LG＞HG;2016~2017年CK、LG、HG之间差异不显著(P＞0.05),2018年CK与LG、HG之间差异显著(P＜0.05)。(4)植物群落Pielou均匀度指数、Shannon-Wiener多样性指数和Margalef丰富度指数与地上生物量在LG、HG和CK条件下,均呈现正线性相关关系(P＜0.05)。【结论】 不同放牧强度下,山地草甸植物群落Simpson优势度指数、Pielou均匀度指数和Shannon-Wiener多样性指数随放牧强度的增加而降低;群落地上生物量与均匀度指数、多样性指数和丰富度指数均有显著的正线性相关关系(P<0.05)。

关键词: 山地草甸草地, 放牧强度, 植物多样性, 地上生物量, 相关性