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Chinese Journal of Applied Ecology ›› 2023, Vol. 34 ›› Issue (3): 614-622.doi: 10.13287/j.1001-9332.202303.002

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Variation characteristics of microorganisms at different soil depths of typical forests in southwest China.

DING Shuang1, WEI Shengzhao1, CHEN Zhenliang2, SHAO Jing3, DUAN Fengrui4, YAN Yu5, DUAN Xingwu1*   

  1. 1Institute of International River and Eco-security, Yunnan University, Kunming 650500, China;
    2School of Life Sciences, Yunnan University, Kunming 650500, China;
    3School of Earth Sciences, Yunnan University, Kunming 650500, China;
    4School of Chemical Science and Technology, Yunnan University, Kunming 650500, China;
    5School of Information Science and Engineering, Yunnan University, Kunming 650500, China
  • Received:2022-08-10 Accepted:2022-10-21 Published:2023-09-15

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Abstract: Microbial biomass and community structure play a significant role in soil carbon cycling. There is a large amount of organic carbon in the subsoil, but most studies on soil microbial community have focused on the surface soil. The changes and influencing mechanisms of microbial community in subsoil are unclear. We analyzed soil microbial biomass and community structure at different soil depths (0-20, 20-40, 40-60, 60-80, and 80-100 cm) in three typical forests in southwest China, Xishuangbanna tropical rain forest, Ailao Mountain subtropical broad-leaved forest, and Lijiang temperate coniferous forest, by using phospholipid fatty acid technology, to explore their variation characteristics and influencing factors in different forests and soil depths. The results showed that contents of soil organic carbon and total nitrogen decreased gradually, microbial biomass declined significantly. The ratio of Gram-positive bacteria to Gram-negative bacteria (G+:G-) reduced gradually, while the ratio of fungi to bacteria (F:B) increased with the increasing soil depth. Microbial community turned from G--dominated which adapted to eutrophic environment into G+-dominated which adapted to oligotrophic environment. The three forest types differed little in soil microbial biomass, but different significantly in microbial community structure. Ailao Mountain subtropical broad-leaved forest and Lijiang temperate coniferous forest had much higher F:B at 0-20 cm than Xishuangbanna tropical rain forest, while significantly higher G+:G- at 0-100 cm in Xishuangbanna tropical rain forest was observed. Results of the redundancy analysis showed that the contents of soil organic carbon and total nitrogen were the main factors determining microbial biomass, with combined explanation of 78.3%. Results of the stepwise regression analysis showed that C:N was the most important driving factor on F:B and G+:G-. The change in microbial community structure and the decrease in biomass along soil profile might strongly affect the dynamics of soil organic carbon in southwest China forests.

Key words: vertical distribution, soil profile, soil layer, phospholipid fatty acid (PLFA), microbial community structure