The grasslands of Campos de Cima da Serra region, located in NE Rio Grande do Sul, were originally occupied by extensive cattle ranching. However, in the 1950s, a transition took place in land use from native vegetation to modern cash crop agriculture, which comprised mainly annual grain crops and apple orchards. This study applied remote sensing techniques for spatial and temporal detection of human-induced land use changes in this 50-years period to a pilot area, including part of the urban area of Vacaria and agricultural land to the north of this city. The earliest available aerial photos, from 1964, allowed assessment of initial shifts in land use. Subsequent temporal analyses relied on Landsat imagery from the 70s, 80s and 90s, and a 2005 EROS-A high resolution image. These analyses produced land use maps, which were overlayed, resulting in a land use evolution map from the beginning of agriculture up to the present day. Approximately 40% of the original grasslands were converted to annual grain crops. Conversion rates of grasslands into other uses were about 1.4 km² year-1 in the 1960-1995 period, and 0.7 km² year-1 from 1996 to 2005. On the other hand, areas of forests and riparian forests have not changed significantly throughout the study period.
geoprocessing; remote sensing; land use change; Campos de Cima da Serra
