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Acta Prataculturae Sinica ›› 2024, Vol. 33 ›› Issue (4): 1-11.DOI: 10.11686/cyxb2023198

   

Effects of grazing exclusion and fertilization on alpine meadow community characteristics and vegetation carbon and nitrogen pools

Rui-min QIN1,2(), Si-jia CHENG1,3, Li MA1, Zhong-hua ZHANG1, Jing-jing WEI1,4, Hong-ye SU1,2, Zheng-chen SHI1,2, Tao CHANG1,2, Xue HU1,2, De-ha-ze A1,2, Fang YUAN1, Shan LI1, Hua-kun ZHOU1()   

  1. 1.Qinghai Provincial Key Laboratory of Cold Regions Restoration Ecology,Northwest Institute of Plateau Biology,Chinese Academy of Sciences,Xining 810008,China
    2.University of Chinese Academy of Sciences,Beijing 100049,China
    3.College of Eco-Environmental Engineering,Qinghai University,Xining 810016,China
    4.College of Geography Science,Qinghai Normal University,Xining 810008,China
  • Received:2023-06-04 Revised:2023-07-24 Online:2024-04-20 Published:2024-01-15
  • Contact: Hua-kun ZHOU

Abstract:

The objective of this study was to determine how two different restoration measures, i.e., grazing exclusion and fertilization, affect degraded alpine meadows. A field study was conducted to compare the effects of grazing exclusion for various periods (0, 4, 13 yrs) and long-term fertilization (with nitrogen, N, and phosphorus, P) on community characteristics and vegetation carbon (C) and N pools. The results showed that: 1) The species richness index and Shannon-Wiener index decreased significantly with increasing years of grazing exclusion, while Simpson’s index and the Pielou index increased and then decreased. The addition of N and P fertilizers significantly decreased the species richness index and Shannon-Wiener index. 2) Aboveground biomass and root biomass were significantly increased after both 4 and 13 years of grazing exclusion, reaching the maximum at 4 years, whereas litter biomass increased gradually with increasing years of grazing exclusion. The effect of long-term fertilization on biomass was not significant. 3) After grazing exclusion, vegetation C and N stocks increased significantly, with aboveground biomass and root C and N pools being highest at 4 years of grazing exclusion, and litter C and N pools being highest at 13 years of grazing exclusion. Long-term fertilization had no significant effect on vegetation C stocks, and only long-term N addition significantly increased the aboveground biomass N pools. 4) Partial least squares path modeling showed that grazing exclusion and fertilization led to changes in environmental factors that restrained community diversity and promoted the accumulation of plant biomass and vegetation C pools, while fertilization affected vegetation N pools. In summary, grazing exclusion generally restrained species diversity, but promoted community productivity and increased vegetation C and N pools, while long-term N addition had no significant positive effect on species diversity and vegetation C pools, but increased vegetation N pools.

Key words: grazing exclusion, long-term fertilization, community characteristics, vegetation carbon and nitrogen pools, alpine meadow