Differential impacts of grazing on grassland plant diversity, biomass, soil C and N across an elevation gradient

Understanding how vegetation traits and soil characteristics respond to grazing in grasslands is fundamental to their restoration and management. Here, we investigated changes in species diversity, plant productivity, soil total nitrogen (STN) and soil organic carbon (SOC) storage following grazer exclusion at three grassland sites along an elevation gradient in the Kashmir Himalaya. Plant cover, above- and below-ground biomass (AGB and BGB, respectively), SOC and STN increased following six years of grazing exclusion, though species diversity indices declined over this period. Grazer exclusion increased the biomass of all functional groups (sedges, grasses, legumes, and forbs), with sedges, particularly Carex muricata, showing the highest increase. Grazer effects on above- and below-ground biomass, SOC and STN varied with elevation, with the most pronounced effect of grazing detected at the highest elevation site. Grazer effect on the vertical distribution of root biomass, SOC and STN were restricted to topsoil (10 cm) at low-elevation sites, but extended to deeper layers of soil at high-elevation sites.