Effects of Different Grazing Intensities on Vegetation Community Characteristics and Soil Aggregates in Xilamuren Grassland

Abstract

[Objective] In order to explore the changes of vegetation communities under different grazing intensities in grassland, the effects of community characteristics on soil aggregates were analyzed. [Methods] Taking the controlled grazing experimental area of Xilamuren desert steppe as the research object, the characteristics of vegetation community and soil aggregates under light grazing (LG), moderate grazing (MG), heavy grazing (HG), and no grazing (CK) and their relationship were analyzed by field investigation and indoor analysis, and the effects of plant community changes on soil aggregates were revealed. [Results] (1) The Shannon-Wiener diversity index (H′) and Simpson dominance index (D) of LG were significantly lower than those of other grazing intensities (p<0.05). The aboveground biomass decreased with the increase of grazing intensity, and the aboveground biomass of HG was significantly lower than that of other grazing intensities (p<0.05). The underground biomass under different grazing intensities was significantly different, and the underground biomass of different soil layers was the highest in LG. (2) The change trend of mean weight diameter (MWD) and geometric mean diameter (GMD) was consistent with the content of macroaggregates. In 0—5 cm and 5—10 cm soil layers, it increased first, then decreased and then increased with the increase of grazing intensity (LG was the highest and MG was the lowest). (3) Shannon-Wiener diversity index (H′), Pielous evenness index (J′), aboveground biomass, and bulk density were significant factors affecting macroaggregate content, MWD, and GMD (p<0.05). [Conclusion] Grazing intensity had a negative feedback regulation effect on soil aggregate stability, which mainly caused the change of soil aggregate stability by affecting the changes of vegetation community diversity index (H′ and J′), aboveground biomass, and soil bulk density. The results provide theoretical support and a scientific basis for the selection of grazing intensity and ecological restoration in Xilamuren grassland.

Keywords

• desert steppe
• grazing intensity
• vegetation communities
• diversity index
• soil aggregates