THE IMPACT OF HEAVY GRAZING ON SOIL QUALITY AND PASTURE PRODUCTION IN RANGELANDS OF SW SPAIN

摘要

Soil degradation phenomena, including water erosion and physical and biological processes, have already been reported in rangelands of southwestern Spain. The increasing numbers of livestock since 1986 have been highlighted as one of the key causes. The main goal of this work is to analyse the effects of the excessive number of animals on soil quality and pasture production on privately owned farms dedicated to extensive ranching. Soil properties and surface cover, pasture production, rainfall and land management variables such as livestock density were analysed during a period of 3years (2008-2011). The study was carried out in 22 livestock enclosures selected from ten farms distributed throughout the Spanish region of Extremadura. The occurrence of bare soil patches and water erosion processes, as well as an increase of mean bulk density in the soil layer from 5 to 10 cm in depth, was observed in the enclosures with animal stocking rates exceeding 1AUha(-1). Indications that confirm the negative effects of increased bulk density on pasture production and quality were also found. Copyright (c) 2016 John Wiley & Sons, Ltd.