Chin J Plant Ecol ›› 2021, Vol. 45 ›› Issue (1): 74-84.DOI: 10.17521/cjpe.2020.0316

• Research Articles • Previous Articles     Next Articles

Effects of long-term human disturbances on soil microbial diversity and community structure in a karst grassland ecosystem of northwestern Guangxi, China

PEI Guang-Ting1,2, SUN Jian-Fei1,2, HE Tong-Xin1,2,*(), HU Bao-Qing1,2   

  1. 1Key Laboratory of Environment Change and Resources Use in Beibu Gulf, Ministry of Education, Nanning Normal University, Nanning 530001, China
    2Guangxi Key Laboratory of Earth Surface Processes and Intelligent Simulation, Nanning Normal University, Nanning 530001, China
  • Received:2020-09-21 Accepted:2020-11-24 Online:2021-01-20 Published:2021-01-07
  • Contact: HE Tong-Xin
  • Supported by:
    National Natural Science Foundation of China(41807523);National Natural Science Foundation of China(41701605);Natural Science Foundation of Guangxi(2017GXNSFBA198034);Natural Science Foundation of Guangxi(2017GXNSFBA198169);Natural Science Foundation of Guangxi(AD19110142)

Abstract:

Aims Human disturbance is one of the main obstacles to the forward succession of karst grassland, exploring the response of grassland to disturbance in terms of soil microorganism can provide the basis for the restoration and rational utilization of karst land. Our objective was to study the effects of different human disturbances on soil microorganisms and the underlying mechanisms in a karst grassland ecosystem of northwestern Guangxi, China.
Methods Three patterns of disturbances (burning, mowing, and mowing plus root removal) and one control treatment (enclosure) were conducted at the long-term monitoring plots in the Huanjiang Observation and Research Station for Karst Ecosystems, Chinese Academy of Sciences. We analyzed the changes of soil microbial diversity and community structure by high-throughput sequencing, and determined their relationships with environmental factors (slope position, soil physicochemical properties).
Important findings 1) For α diversity, at both middle and lower slope positions, the burning treatment significantly reduced the fungal Chao1 index, while the mowing treatment significantly reduced the bacterial Shannon index and Pedigree diversity index. However, the mowing plus root removal treatment significantly reduced the fungal Chao1 index and the bacterial Shannon index, respectively, at middle and lower slope positions. 2) For microbial community structure, burning, mowing and mowing plus root removal treatments significantly reduced the relative abundance of Acidobacteria at both middle and lower slope positions, while the fire treatment significantly reduced the relative abundance of Ascomycota from 74.49% to 34.72% at the lower slope position. 3) Redundancy analysis showed that soil microbial biomass carbon explained 29.8% and 26.8% of the changes of bacterial and fungal α diversity, respectively, and 31.7% of the changes of bacterial community structure. Root biomass explained 13.9% and 10.3% of the changes of bacterial α diversity and fungal community structure, respectively. In conclusion, the three studied human disturbances have significantly negative influence on soil microbial α diversity as well as having a significant change in and changed community structure, and the degree of influence varied among the pattern of disturbances and the type of microorganisms. Moreover, the effects were also regulated by slope position. Long-term human disturbances mainly affected the diversity and structure of soil microbial communities by changing soil microbial biomass carbon and root biomass. The decreases of α diversity and Ascomycota will not be conducive to the maintenance of soil ecosystem stability, and the decrease of Acidobacteria will not facilitate to soil organic matter degradation and iron cycling. Therefore, the long-term human disturbances such as burning and mowing will induce the functional degradation of grassland ecosystem.

Key words: karst, burning, mowing, root removal, microbial diversity, microbial community structure, high-throughput sequencing