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Acta Prataculturae Sinica ›› 2023, Vol. 32 ›› Issue (11): 93-105.DOI: 10.11686/cyxb2023020

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Changes in soil bacterial carbon source utilization and soil extracellular enzyme activity after artificial planting of Caragana korshinskii at different densities on the desert steppe

Rong-xia SU(), Yan-ping MA, Hong-mei WANG(), Ya-nan ZHAO, Zhi-li LI   

  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:2023-01-06 Revised:2023-03-06 Online:2023-11-20 Published:2023-09-27
  • Contact: Hong-mei WANG

Abstract:

The aim of this study was to explore the effects of shrub introduction on the functional diversity of soil bacterial communities and soil extracellular enzyme activity on the desert steppe. Field studies were conducted in areas where Caragana korshinskii has been introduced with different planting intervals into grassland on the desert steppe of eastern Ningxia. We investigated the characteristics of soil bacterial carbon utilization in fenced grassland and shrublands planted with C. korshinskii at a range of intervals (40, 6 and 2 m) using the Biolog-ECO method. We found that the soil organic carbon and microbial biomass carbon contents were not significantly higher in shrublands than in enclosed desert grassland, while soil total carbon content was significantly higher (by 26.65%-43.47%) in shrublands than in enclosed grassland. The activities of all measured soil extracellular enzymes, except β-1,4-N-acetylamino glucosidase, were lower in shrublands than in enclosed grassland, but there was no significant difference in their activities among the different planting intervals. Further analyses including a principal component analysis revealed significant differences in the metabolic functions of soil bacterial communities among sites. The relative utilization of carbon sources decreased by 49.2% with the increase of shrub introduction intervals in the last 30 years. The utilization of carbon sources by soil bacteria and the functional diversity of soil bacterial communities were significantly higher in shrublands than in enclosed grassland. The Shannon-Wiener richness index, Shannon’s evenness index, and Simpson’s dominance index of soil bacterial communities increased with increasing planting intervals of C. korshinskii. Soil bacteria in grassland mainly utilized amino acids, polymers, and other types of compounds as carbon sources, but those in shrublands stably utilized polymers and amino acids as carbon sources.

Key words: desert grassland, shrub introduction, different densities, soil bacteria, carbon source utilization