Productivity of natural grasslands in different geomorphological units of the Sierras Pampeanas of Argentina

Abstract

In the semi-arid areas of Argentina there is a variation of the natural grasslands associated with different landscape units. Digital terrain models are tools that have allowed the study of the physical variables of the environment and the dynamics and patterns of semi-arid ecosystems. For this reason, the objective of our work was to determine if there are differences in the productivity and botanical composition of the natural grassland in the different geomorphological units identified. The quantification of the amount of biomass was carried out by the method of double sampling and botanical composition by the method of assigning ranges. To determine the geomorphological properties, a digital model of the terrain was used, where the following were considered: slope, slope orientation, altitude, terrain roughness index and topographic humidity index. Differences were found in terms of the productivity and botanical composition of the natural grassland, influenced directly and indirectly by geomorphological characteristics such as height, slope and roughness. The decades-long history of overgrazing in the foothills of the study area has contributed to grassland degradation through the loss of palatable perennials and the installation of low-quality and annual species. It is necessary to add sampling stations with broader time scales taking into account grazing pressure.