The real western boundary of Pampa grasslands

Abstract

The current mapping on land-cover distribution restricts the Argentinean Pampa grasslands to the Buenos Aires, Córdoba, Santa Fe, Entre Ríos, La Pampa and San Luis provinces. In this study, we reviewed the western distribution of these grasslands by using remote sensing analyses and “in situ” evaluations. We used a 10-years series of MODIS/Terra satellite images as a basis to locate and map the area of study. We also employed a non-supervised classification (ISODATA), complemented with a visual interpretation on Landsat 8 satellite images, to classify pixels into two categories: grassland and shrubland. The accuracy of this classification was 89.1%, verified through an error matrix by using high resolution images from Google Earth. We identified a new area of 3050 km² of Pampa grasslands that was not considered in previous land-cover vegetation maps. This area, previously categorized as shrublands, is located west of the Salado river, at the south-east of Mendoza and north-center of La Pampa provinces, between 35.362° and 36.257° S, and 66.613° and 67.264° W. Vegetation surveys in specific sites showed that they are typical semiarid Pampa grasslands, dominated by C4 perennial tussocks of Elionurus muticus (28% of area cover). Other important species, with area covers between 1 and 5%, were Hyalis argentea, Sporobolus cryptandrus, Aristida mendocina, Bothriochloa springfieldii and Eragrostis lugens. The inherent low replacement rate that occurs in this semiarid region of Argentina enhances the importance of these grasslands as reservoirs of this fragile ecosystem.