JULIAN CHARÁ, L. GIRALDO, D.J. CARRILLO, JUAN CARLOS CAMARGO, GLORIA XIMENA PEDRAZA ORDÓÑEZ
Centre for Research on Sustainable Agricultural Production Systems (CIPAV), Colombia
Cattle ranching is a key economic sector of the Colombian economy, contributing 27 percent of agricultural and livestock GDP and 28 percent of rural employment. This activity occupies about 38 percent of Colombia's total land surface, an area that has expanded from 14.6 to 38 million hectares during the last fifty years, mainly at the expense of tropical forest. Through its impact on Andean and Amazon Basin forests, ranching-induced deforestation has historically been one of the main causes contributing to the loss of unique plant and animal species in Colombia. A great proportion of the deforested area is nowadays covered by degraded pastures. This has affected not only biodiversity but also soils since 66 percent of the land used as permanent pasture is degraded and otherwise unsuitable for grazing. The destruction of forests and the degradation of soils, among other factors have resulted in a degradation of water resources which has affected not only water quality but also aquatic habitats from springs and small streams to rivers, wetlands and estuaries.
Although studies of the impact of cattle ranching on water environments are scarce, several investigations have demonstrated that the activity negatively affects water environments in the Andean and Amazons regions, mainly by reducing the quality of the physical habitat in streams and by increasing organic matter and reducing oxygen concentration in the water. However, there are alternatives for reducing damage by cattle which include the protection of springs and water courses, reduction of the effect of diffuse pollution and the transformation of homogeneous pastures into silvopastoral systems. With these practices, cattle grazing can contribute to improve water quality and regulate the hydrological cycle at micro-watershed level with benefits for the environment and local population.
This work briefly describes the history of cattle occupation in Colombia, explains the environmental impacts of this activity with particular reference to aquatic environments and presents the effect of riparian corridors and other measures based on silvopastoral systems on the reduction of soil degradation, and improvement of water quality, habitat properties and aquatic biodiversity in the Andes of Colombia.
Keywords: Cattle, environmental impact, pastures, tropical streams, watersheds