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Acta Prataculturae Sinica ›› 2021, Vol. 30 ›› Issue (8): 1-11.DOI: 10.11686/cyxb2021027

   

Effects of different stocking rates on interspecific relationships among dominant species and their spatial distribution characteristics in the Stipa breviflora desert steppe

Feng ZHANG1,2(), Jia-wei SUN1,2, Yu SUN1,2, Jia-hua ZHENG1,2, Ji-rong QIAO1,2, Meng-li ZHAO1,2()   

  1. 1.College of Grassland,Resource and Environment,Inner Mongolia Agricultural University,Hohhot 010019,China
    2.Key Laboratory of Grassland Resources,Ministry of Education of China,Inner Mongolia Agricultural University,Hohhot 010019,China
  • Received:2021-01-20 Revised:2021-03-08 Online:2021-07-09 Published:2021-07-09
  • Contact: Meng-li ZHAO

Abstract:

The aim of this study was to explore the effects of different stocking rates on the relationships among dominant plant species and their spatial distribution in the Stipa breviflora desert steppe. A field study was conducted from July to September 2020 in the Siziwang Banner, Inner Mongolia. The constructive species S. breviflora and the dominant species Cleistogenes songorica and Artemisia frigida were selected as the research objects. Different stocking rates corresponding to the control, light grazing, moderate grazing, and heavy grazing (0, 4, 8, and 12 sheep grazing, respectively) were established. We analyzed the frequency, abundance, strength of interspecific relationships, and spatial distribution characteristics of the constructive and dominant species combining conventional methods and geostatistical methods. The results show that: 1) The frequency of A. frigida was significantly decreased (by 50.55%) in the light grazing treatment as compared with the control (P<0.05) in July, while moderate and severe grazing significantly reduced its frequency from July to September (P<0.05). The average decreases in the frequency of A. frigida from July to September were 77.76% (moderate grazing) and 97.53% (heavy grazing). The frequency of S. breviflora and C. songorica did not differ significantly among different stocking rates and among different months (P>0.05). 2) Compared with the control, the light, moderate, and heavy grazing treatments resulted in increased abundance of S. breviflora (by 37.34%, 75.72%, and 99.32%, respectively), and decreased abundance of A. frigida (by 61.26%, 66.32%, and 99.31%, respectively) from July to September (P<0.05). The species abundance of C. songorica increased significantly from July to September in all treatments, except for the light grazing treatment in September (P<0.05). 3) S. breviflora and C. songorica mainly showed an affinity relationship, but showed a competitive relationship in the heavy grazing treatment in September. S. breviflora and A. frigida mainly showed a competitive relationship, and grazing did not change this interspecific relationship. 4) S. breviflora and C. songorica had stronger effects on A. frigida, while A. frigida had weaker effects on S. breviflora and C. songorica. 5) Finally, a simulation of the spatial distribution among dominant species in September revealed that the abundance of S. breviflora increased with increasing abundance of C. songorica in the control, and decreased with increasing abundance of A. frigida. In the heavy grazing treatment, the abundance of A. frigida was not affected by the abundance of S. breviflora and C. songorica. As the abundance of C. songorica increased, the abundance of S. breviflora tended to decrease, indicating that the relationship between S. breviflora and C. songorica changed from an affinity relationship in the control to a competitive relationship under heavy grazing. In summary, these results show that grazing can change intra-specific abundance and inter-specific relationships among dominant plant species.

Key words: desert steppe, interspecific relationship, spatial distribution