Response of plant functional groups to different grazing management systems in summer grasslands on the northern slope of Tianshan Mountains

The response process of grassland ecosystems, in terms of productivity and functional diversity, to grazing management systems is highly complex. This poses a major challenge in studying the response of plant communities to environmental changes. An effective approach to reducing the complexity of ecological community research is categorizing species with similar characteristics into plant functional groups. In this paper, the plant communities in the study area were divided into four functional groups (sedges, grasses, leguminous grasses, and weeds) to study the response of the community to a grazing management system that adjusted the entry time of livestock into the grasslands, without reducing grazing intensity and grazing duration. Compared with the traditional grazing for 60 days in May, delaying livestock grazing to June and July increased the dominant position of fine herbage and reduced the position of forbs in the community’s functional groups. Partial Least Square (PLS) analysis indicated that grazing management, soil variables, and climate variables had weak direct effects on functional groups. In addition, variance decomposition analysis (VPA) showed that the independent explanation rate of climate variables on the variables related to each functional group was 0, and that the combined explanation rate of grazing management variables and soil variables was 78.6%. The synergy between the two is the main driving force for changes in the productivity and diversity characteristics of each functional group. The flexible grazing management system is superior to the traditional grazing management system. It not only maintains the long-term sustainability and profitability of livestock production, but also maintains and develops a high biodiversity and the multifunctionality of grasslands, which is worthy of further research.