Agricultural and Biological Research

Impact of settlement-type grazing on rangeland vegetation in the Inner Mongolia autonomous region: A field verification of case study through a grazing experiment

Tian Ying, Hai Rihan, Yong Hai, Myagmartseren Purevtseren and Buho Hoshino*

Understanding the ingestive behavior and daily voluntary intake of grazing livestock is important for sustainable land use and management of pasturelands. Since the 1990s, Inner Mongolia has completely converted from old nomadic grazing to settled grazing, and many small fences have been built around settled areas, where livestock are placed inside the fences and grazed. Currently, desertification of grasslands is progressing in a mosaic pattern around the fence. There have been few quantitative studies of individual sheep foraging behavior in confined spaces and changes in plant community composition associated with foraging. The study was conducted in Abag Banner (an administrative unit of China equivalent to a county), located in the northern part of the Xilingol Autonomous Region of Inner Mongolia, which borders Mongolia. This study aimed to quantitatively evaluate the impact of livestock ingestive behavior on pasture vegetation in the sedentary grazing area of Inner Mongolia and to provide basic data for the sustainable use of pastureland. Three sites were established in a sedentary grazing area, where tethering grazing experiments (hemp rope length of 6 m) were conducted. Quadrats of 1 × 1 m were established inside (four quadrats) and outside (five quadrats) each site for the vegetation survey, and plant species identification, plant height, vegetation cover, and soil hardness were evaluated. Livestock (sheep) instinctively selected and fed on high-palatability plants instantaneously after the start of the tethering grazing experiment. The increased grazing intensity over 5 days and the grazing of high-palatability plants decreased plant height and aboveground biomass; however, the botanical composition remained unchanged. The Shannon diversity index value decreased from 1.97 to 1.60 on day 4, and the vegetation cover decreased from approximately 80% to <10%. For aboveground biomass, only 15%-54% remained. Salsola collina Pall. and Caragana microphylla Pall. shrubs, which had low aboveground biomass from the start, were barely grazed, whereas Agropyron cristatum L., with high palatability, was left with only 15% biomass. The soil hardness increased by 1.25 and 0.25 mm at sites A and B, respectively, and decreased by 0.63 mm at site C. This indicated that the soil was locally bare, and the topsoil was destroyed.