Effects of grazing intensity on plant richness and diversity: a meta-analysis

Most of our knowledge of the effect of grazing on grassland structure is based on grazed-ungrazed contrasts. The effects of grazing in the most common scenario, where grazing intensity varies from low to high grazing intensity, are less known. The objectives of this paper were to (1) quantify the effect of stocking rates on species richness and diversity of grasslands world-wide, and (2) evaluate the response under different environmental and experimental conditions. We conducted a meta-analysis of experiments with at least two levels of controlled stocking rates and evaluated their effect on species richness and diversity. The results showed that the response of richness and diversity to either reducing or increasing stocking rate from a moderate level mostly fell within the range ± 25% or ± 5 species. Mean response of species richness and diversity to increasing stocking rate from moderate to high levels was negative. Mean response to lowering stocking rate from moderate levels was no...