Grazing season regulates plant community structure and production by altering plant litter mass in a typical steppe

Abstract

AbstractAimsGrazing different grasslands with seasonal changes is the tradition in pastoral systems in natural grassland regions worldwide. The effects and mechanisms of different grazing seasons on semi‐arid steppe vegetation are less explored on the Mongolian Plateau. Therefore, we assessed the impact and underlying mechanisms of grazing seasons on grassland community structure and production.LocationXilingol, Inner Mongolia, China.MethodsWe conducted a three‐year experiment to investigate the effects of grazing in four different seasons under the same grazing intensities on plant community structure and production in a typical steppe rangeland. The experiment was a random‐block design, with 20 grassland paddocks of 50 m × 50 m, representing five treatments (i.e., early spring, summer, autumn, mid‐winter, and no grazing), replicated by four blocks. We monitored the changes in soil properties, plant litter mass (i.e., standing dead biomass and dead plant material on the soil surface) and plant species composition and production across grazing treatments.ResultsPlant community height and above‐ground biomass were higher under early spring and winter grazing than autumn and summer grazing and no grazing. This divergence in plant community structure was mainly mediated by the seasonal patterns of plant litter mass across the grazing regimes. A high plant litter mass enhanced soil moisture by accumulating snow in winter and reducing soil evaporation during the growing season, which benefit plant growth. The removal of plant litter before the growing season increased the reception of solar radiation, thus improving soil temperature and plant production. The changes in community microenvironment and selective grazing led to the changes in plant species composition especially under summer and autumn grazing.ConclusionsOur results imply that grazing in winter or in early spring before plants start to turn green is more efficient than the complete animal exclusion for the natural recovery of degraded grassland in Inner Mongolia. It is suitable to incorporate cold‐season grazing in the development of sustainable grassland management systems.