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Acta Prataculturae Sinica ›› 2019, Vol. 28 ›› Issue (5): 15-25.DOI: 10.11686/cyxb2018302

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Plant community structure and species diversity differences in alpine grassland in the Qilian Mountains with different levels of degradation

ZHANG Jian-gui1, WANG Li-de2, YAO Tuo1,*, LI Hai-yun1, GAO Ya-min1, YANG Xiao-mei1, LI Chang-ning1, LI Qi1, FENG Ying1, HU Yan-ting3   

  1. 1.College of Grassland Science, Gansu Agricultural University, Ministry of Education Key Laboratory of Grassland Ecosystem, Lanzhou 730070, China;
    2.Gansu Desert Control Research Institute, Lanzhou 730070, China;
    3.College of Forestry, Gansu Agricultural University, Lanzhou 730070, China
  • Received:2018-05-09 Revised:2018-07-20 Online:2019-05-20 Published:2019-05-20
  • Contact: E-mail: yaotuo@gsau.edu.cn

Abstract: This research aimed to provide a theoretical basis for effective management, productivity improvement, biodiversity protection, and sustainable resource use in the restoration of Kangle grassland in the Qilian Mountains. The plant community structure and soil characteristics at selected sites with different levels of degradation were sampled and analyzed. Five diversity indexes (the Margalef index, Dominance index, Simpson index, Evenness index and Shannon index) were used to explore changes in species diversity. The results showed that: 1) As expected, aboveground biomass, vegetation height and ground cover, plant density, and plant frequency showed a decreasing trend (P<0.05), from lightly degraded grassland (LDG) to moderately degraded grassland (MDG) and from MDG to severely degraded grassland (SDG). 2) There were 39 species, 35 genera and 15 families in the study area. The plant community had strong ecological adaptability, which was mainly represented by the Fabaceae, Rosaceae, Poaceae, Asteraceae and Cyperaceae families. The dominant species of different degradation degrees were: LDG, Poa pratensis and Polygonum viviparum; MDG, Leymus secalinus and Kobresia humilis; SDG, K. humilis and L. secalinus. Poaceae had a key role in the stability of the community. 3) In defining functional groups in alpine grassland, it was found that forb plants were of primary importance, followed by graminoid plants, with harmful grass plants the least important. The importance values of forb plants at differing grassland degradation levels were 75.14% (SDG)>48.67% (LDG)>30.05% (MDG). The importance values of harmful grass plants at differing grassland degradation levels were 20.81% (LDG)>18.01% (SDG)>17.11% (MDG). 4) The highest species Dominance index within the SDG community was 0.23; the highest Margalef richness index of the LDG was 2.64 and the Shannon comprehensive index of the LDG community was 2.09. 5) With increased degree of degradation, the soil total phosphorus, total nitrogen, organic matter and water contents showed downward trends, while pH increased. In summary, with increasing degree of degradation, the change in grassland community structure exhibited a continuous single trend Kangle, while the major environmentally limiting factors changed.

Key words: west Qilian Mountains, alpine grassland, degraded level, community structure, species diversity