Palatability of herbage, and woody plant encroachment in relation to grazing intensity in semi-arid rangeland in western Iran

Overgrazing is the main factor causing rangeland degradation in Iran. The main objectives of this study were to investigate the influence of grazing intensity on the palatability of the herbage and how bush encroachment is related to long-term grazing pressure. Herbage palatability was assessed as the weighted palatability composition of the vegetation considering palatability classes and the abundance of herbaceous and woody plant species. Grazing intensity as a management factor was estimated based on the livestock number of different grazing areas. To this end, 43 main plots were sampled in the rangeland areas of two catchments in the south-east of Kermanshah. High grazing intensity was negatively associated with biomass, species richness, herbaceous cover and palatability. Furthermore, the results indicated that encroachment of the rangeland by shrubs and invader species probably resulted from overgrazing. The results hint at overgrazing as a main factor for decreased palatability of the herbage in rangelands in Kermanshah.