LIVESTOCK AND NATURAL RESOURCES IN A NATURE RESERVE IN SOUTH SONORA, MEXICO

Cattle ranching is the main activity and the principal user of natural resources in Alamos, Mexico, extending in 93% of this municipality. The objective of this study was to assess the impact of livestock production on natural resources, in the municipio of Alamos, Sonora and in the “Sierra de Ãlamos-Río Cuchujaqui†nature reserve, which was established in 1996. Overgrazing, deforestation, botanical composition of the rangeland, soil cover and soil erosion risk were the main indicators evaluated. From 1995 to 2005 livestock herd size increased by 13%. By the year 2005, overgrazing was over 200% in all the sites evaluated, (reaching values as high as 550%), taking as a reference COTECOCA (the Mexican agency for the determination of rangeland grazing load) recommendations for animal rangeland load. Deforested area within the nature reserve remained relatively unchanged in 5,150 ha between 1996 and 2006. In the 155 sites sampled for vegetation and soil cover, on the other hand, we found a low percentage of cattle-preferred species, whereas species with low nutritional quality and less preferred by the cattle, represented 65 to 90% of the identified plants