Effects of spring rest grazing on dominant populations and species diversity

The aims of this study were to explore changes in the importance values of dominant populations and species diversity of grassland plant communities under different grazing utilization modes, clarify the relationship between the importance values of dominant population and species diversity, and provide theoretical and data support for the sustainable management of desert steppe ecosystem. The research was conducted in the Stipa breviflora desert steppe after spring rest grazing. The study used a randomized block design with three treatments: control (CK), spring rest grazing + summer heavy grazing + autumn suitable grazing (SA₁), and spring rest grazing + summer suitable grazing + autumn heavy grazing (SA₂). Comparative and advantage analyses were conducted to explore changes in the importance values of dominant populations and species diversity. In the order of CK, SA1, and SA2, the mean importance value of S. breviflora showed an upward trend, the mean value of important value of C. songorica was lower under SA1 treatment, the mean importance value and richness index of A. polyrhizum showed a downward trend, the dominance and diversity indices were higher under SA1, and the evenness index was lower under SA1. The association between the importance value of S. breviflora and species diversity only changed under SA2 treatment. Grazing was found to change the importance value of dominant populations and dominance order of species diversity. According to the dominance analysis of the absolute correlation matrix, the dominance order of species diversity under different treatments from highest to lowest was as follows: richness index, diversity index, dominance index, and evenness index. According to advantage analysis of the comprehensive correlation matrix, S. breviflora occupies a dominant position in the dominant population under the CK treatment, C. songorica occupies a dominant position in the dominant population under the SA1 treatment, and A. polyrhizum occupies a dominant position in the dominant population under the SA2 treatment.