Assessment of grazing-induced degradation of arid and semiarid rangelands with stochastic rainfall regimes is challenging. To assess grazing impacts on vegetation under highly variable environments, we focused on resource variations in relation to the scale of local rangeland use. Specifically, we tested the hypothesis that grazing impacts on resources were greater in areas heavily used during drought (i.e. key resource areas) than elsewhere. Near Mandalgobi, Mongolia, we established study sites in four typical vegetation communities (Caragana, Allium, Achnatherum and Reaumuria) according to landscape type. First, we interviewed key informants about the four community types to examine how local pastoralists used these communities during normal and drought summers. Second, we compared dung pellets numbers among communities to quantify the different grazing impacts on each community. Finally, to determine grazing impacts on vegetation in each community, we performed vegetation surveys in grazing and non-grazing plots at each site. According to respondents, during normal summers all types of community were used, but during drought, the main community used was Achnatherum community. The number of dung pellets was highest in the Achnatherum community. Species composition was significantly more affected by grazing in the Achnatherum and Reaumuria community than in the other communities. These results suggested that the Achnathrum community would have a role of key resource in study sites and grazing impacts affected key resource areas. If rangeland management is focused only on maintaining resource accessibility, then grazing-induced degradation of key resource areas could occur even on highly variable rangelands.
ASJC Scopus subject areas
- Ecology, Evolution, Behavior and Systematics
- Agronomy and Crop Science
- Plant Science