Highland grassland vegetation in the northwestern Andes of Argentina: Vegetation structure and species composition in relation to grazing

In the Andean Cordillera, natural grasslands above 2500 m are used for livestock grazing. Few studies on the effects of foraging natural vegetation have been conducted in the northern Argentinean Andes, although this activity is frequently considered to be involved in the dragging of large amounts of sediment and in soil erosion after summer rainfall. The present study aims to identify and describe floristic composition in main vegetation units, and the potential and susceptibility of these units to foraging within a small catchment in the Andes of northwestern Argentina. Vegetation was sampled for total cover, cover per species, altitude, exposure, slope, and foraging pressure. Data are classified and ordered through multivariate analysis. Species are also classified according to life form (shrubby, gramineous/graminoids, and herbaceous) and palatability. Variance Analysis was applied to detect significant differences among vegetation units. In the study area, differences in the floristic composition of vegetation units are associated with grazing, altitude and slope. Our results allow us to propose different uses of vegetation: sectors fit for foraging, sites severely degraded and in need of strict protection, and sites fit solely for moderate firewood extraction are identified.