Changes in the Composition and Diversity of Pasture Grass Due to the Influence of Grazing in the Steppe Zone of Northern Kazakhstan

Abstract

Overgrazing poses a serious threat to the sustainability of steppe pasturelands in Northern Kazakhstan, where intensifying livestock pressure drives significant changes in vegetation composition, species diversity, and soil fertility. This study investigated the effects of grazing intensity on pasture vegetation and chestnut soil properties in the Zhaksyn district of the Akmola region. Field surveys were conducted in July-August 2024 using 75 m transects with 1 m² quadrats across three treatment plots: intensively grazed, moderately grazed, and ungrazed control. Vegetation parameters assessed included species composition, cover, height, yield, and nutritional and energetic quality across spring and summer seasons. Statistical analyses revealed that intensive early-season grazing significantly reduced species richness and plant biodiversity compared to late grazing and control plots. Intensive grazing also increased vegetation heterogeneity through the destruction of dominant species and contributed to a reduction in plant cover. Soil analysis indicated a slight decline in humus content and significant loss of organic matter under intensive grazing due to trampling and reduced vegetation cover, alongside elevated soil salinity associated with increased exchangeable sodium. Moderate grazing, by contrast, showed less severe impacts across all measured parameters. Overall, unmanaged intensive grazing exerts compounding negative effects on both plant community structure and soil health, with implications for long-term pastureland sustainability. These findings highlight the need for regulated grazing management strategies to preserve steppe biodiversity and maintain ecosystem function in Northern Kazakhstan.