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Acta Prataculturae Sinica ›› 2023, Vol. 32 ›› Issue (6): 30-44.DOI: 10.11686/cyxb2022298

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Carbon source utilization by soil bacteria at different lengths of time after introducing shrubs to the desert steppe

Yan-shuo CHEN(), Yan-ping MA, Hong-mei WANG(), Ya-nan ZHAO, Zhi-li LI, Zhen-jie ZHANG   

  1. School of Agriculture,Ningxia University,Ningxia Grassland and Animal Husbandry Engineering Technology Research Center,Key Cultivation Laboratory of Ecosystem Restoration and Reconstruction,Ministry of Education,Yinchuan 750021,China
  • Received:2022-07-25 Revised:2022-09-07 Online:2023-06-20 Published:2023-04-21
  • Contact: Hong-mei WANG

Abstract:

The aim of this study was to explore the impact of the introduction of shrubs over recent decades on the functional diversity of soil bacterial communities in the desert steppe. Therefore, the carbon utilization characteristics of soil bacteria in the 0-20 cm soil horizon were investigated and analyzed. Soil samples were collected from fenced grassland (17 yr), and grassland at 6, 15 years, and 25 years after the introduction of shrubs. The soil samples were analyzed using the Biolog-ECO method. It was found that the soil total carbon content was up to 43.5% (P<0.05) higher in shrubland than in fenced desert grassland, but did not differ significantly among the three shrublands. The amounts of bacteria and microbial biomass carbon were highest in the 25-year shrubland. Sucrase activity in soil increased significantly with increasing number of years after shrub introduction. Compared with the soil bacterial community in enclosed desert grassland, those in the shrublands showed increased utilization of soil carbon sources (by 92.75%-181.73%). The utilization capacity of six types of carbon sources by soil bacteria was significantly higher in the shrublands than in the enclosed grassland. Sugar, amino acids, and carboxylic acids were the three types of carbon sources preferentially utilized by soil bacteria. The introduction of shrubs into the desert steppe significantly increased the functional diversity of soil bacterial communities, especially in terms of the Shannon-Wiener richness index, Shannon’s evenness index, and Simpson’s dominance index, and the values of these indexes increased with increasing number of years after shrub introduction. The soil total carbon and nitrogen contents were significantly and positively correlated with the functional diversity of soil bacteria (P<0.05) after the introduction of shrubs. To summarize, nearly 30 years after shrub introduction, the bacterial utilization of carbon sources had significantly improved, accompanied by a shift of the main types utilized from amino acids and polymers in grassland to sugars and amino acids in shrubland.

Key words: desert steppe, shrub, years of introduction, functional diversity of soil bacteria