Abstract: Aims
Spatial heterogeneity of key soil resources is fundamental to grassland ecosystem stability and strongly shaped by livestock grazing. Existing research has largely prioritized single livestock species, leaving our understanding of how different species and assemblages regulate soil resources and their spatial patterns relatively limited. This study aims to evaluates the effects of diverse livestock assemblages on key soil resources in alpine grasslands.
Methods
We conducted an eight-year controlled grazing experiment in the alpine grasslands of the Qinghai-Tibet Plateau to evaluate the impacts of yak alone, Tibetan sheep alone, and mixed grazing (ratios of 1:2, 1:4, and 1:6) on key soil properties and their spatial heterogeneity.
Important Findings
Our results indicated that soil available nitrogen, water content, and bulk density were the key physicochemical properties driving changes in plant and microbial communities under grazing. Grazing by Tibetan sheep alone induced the greatest increase in the spatial heterogeneity of soil available nitrogen and compaction (59.41% and 34.76%), whereas grazing by yaks alone caused the most significant rise in the spatial heterogeneity of soil water content (67.24%). Trampling and excretion by livestock accounted for 56.65% to 76.16% of the variation in soil heterogeneity, exerting a stronger influence than the spatial heterogeneity of vegetation communities. These findings highlight the pivotal role of different livestock assemblages in regulating the spatial heterogeneity of key soil resources in alpine grasslands and suggest that future adaptive management must fully consider the specific impacts of different livestock assemblages on soil resources and ecosystem dynamics.

Key words: soil resources, spatial heterogeneity, livestock assemblage, alpine grasslands, Qinghai–Tibetan Plateau