Adaptability of ecological niches and interspecific relationships of grasshoppers in the desert steppe under different grazing intensities

Abstract

Orthopteran insects, which serve a wide range of biogeographic and ecological functions, play multiple roles in maintaining the health and stability of grassland ecosystems. Consequently, they are considered important indicators of ecological changes in grasslands. To assess and maintain ecosystem functionality, it is essential to understand the ecological niches of Orthopteran insects. This includes analyzing niche breadth, interspecific relationships, biological requirements, tolerances, and niche overlap among sympatric species. However, how these ecological dynamics respond to grazing in desert steppe ecosystems remains largely unexplored. Through a grazing experiment initiated in 2004 on desert steppes, with sampling conducted in 2021 and 2022, this study analyzed the response of grasshopper niche width, niche overlap, and interspecific connectivity under different grazing intensities, providing insights into the effects of long-term grazing on the dominant insect group. Results showed that the increase in grazing intensity significantly expanded the niche widths of Myrmeleotettix palpalis and Oedaleus decorus asiaticus, while significantly reducing the niche width of Calliptamus abbreviates. The overlap of grasshopper niches significantly decreased with increasing grazing intensities, suggesting a strategy to mitigate competition amidst reduced plant resources. Concurrently, interspecific associations shifted from non-significant to significantly positive, indicating a potential for ecological facilitation and increased species interdependence under higher grazing pressures. Increases in grazing intensities resulted in grasshoppers adapting their strategies for plant resource utilization in response to environmental changes, which helped to mitigate direct interspecific competition and may have contributed to the development of a more stable ecosystem state.