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Acta Prataculturae Sinica ›› 2023, Vol. 32 ›› Issue (1): 154-164.DOI: 10.11686/cyxb2022165

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Response of soil nematode community structure and diversity to increased nitrogen in alpine meadows of northern Tibet

Yu-bao SHA1,2(), Ganjurjav HASBAGAN1,2(), Guo-zheng HU1,2, Xue-xia WANG3, Jun YAN4, Shi-cheng HE4, Qing-zhu GAO1,2   

  1. 1.Institute of Environment and Sustainable Development in Agriculture,Chinese Academy of Agricultural Sciences,Beijing 100081,China
    2.Nagqu National Experimental Station for Agri-environmental Observation,Nagqu 852000,China
    3.Institute of Plant Nutrition and Resources,Beijing Agricultural Forestry Academy,Beijing 100097,China
    4.Nagqu Grassland Station,Nagqu 852000,China
  • Received:2022-04-12 Revised:2022-05-30 Online:2023-01-20 Published:2022-11-07
  • Contact: Ganjurjav HASBAGAN

Abstract:

Soil nematodes play an important role in material cycling and energy transfer processes in alpine meadow ecosystems. Alpine meadow plants are extremely sensitive to nitrogen deposition, but the effect of increased nitrogen on the structure and diversity of the soil nematode community remains unclear. In this study, we conducted a simulated nitrogen deposition experiment in alpine meadows in Nagqu, Tibet, with four levels of nitrogen enrichment: 0 (CK), 7, 20, and 40 kg N·ha-1·yr-1. Then, we investigated the effects of nitrogen enrichment on the structure and diversity of the soil nematode community. The results showed that: 1) Increased nitrogen significantly changed the soil nematode community composition in alpine meadows and reduced nematode diversity and evenness; 2) the N20 and N40 treatments significantly increased the relative abundance of bacterivore (Ba) taxa by 30.4% and 31.7%, respectively, compared with the control group; 3) The treatments could be ranked, from highest nematode diversity index and evenness index to lowest, as follows: Nck>N40>N20>N7. There were no significant differences in the plant parasite index, maturity index, and Wasilewska index (WI) among the treatments. The nematode channel ratio was greater than 0.5 and the WI was greater than 1 under different nitrogen enrichment conditions, indicating that the soil nematode taxa in the study area were mainly bacterivore nematodes, and that the main players in the mineralization pathway were bacterivore and fungivore nematodes; 4) The ammonia nitrogen content in soil was significantly and positively correlated with the total numbers of nematodes and bacterivores. This study clarified that the increase in the total number of soil nematodes in the alpine meadows of northern Tibet under nitrogen deposition is because of increased numbers of bacterivore nematodes. These results provide a reference for exploring how alpine meadow ecosystems in northern Tibet will respond to nitrogen deposition.

Key words: nitrogen deposition, ecological index, nematode channel ratio, soil fauna, plant productivity