Dinâmica de habitats na região subtropical da América do Sul: Determinantes socioeconômicos e padrões de paisagem em um ecótono floresta-campo

Abstract

We investigated landscape structure and spatialpatterns of natural grasslands and Atlantic Forests in southern Brazil in 1984, 1994, and 2005. The studied region is a highland grassland disjunct region (campos de cima da serra) surrounded by forests. We asked: (a) was there an intensification of habitat loss, fragmentation, and isolation of the Atlantic forest or grassland, within the highland ecotonalzone? (b) What was the degree ofconnectivity/isolation of the patches? (c) Was there any pattern of grassland loss related to moisture/microtopography? (d) Did agroeconomic activities influence landscape patterns and land use change? We analyzed Landsat remotely sensed information to characterize the land use and land cover, also considering subdivision into eight agroeconomicregions. Results showed that the area occupied by agriculture suffered a strong expansion along with exotic tree plantations, at the expense of grasslands, which suffered marked loss and fragmentation. Grassland destruction was biased towards humid areas in valleys between relief undulations. Forests expanded as a network of small patches in close contact with other land uses. Land cover differed significantly among agroeconomic regions, suggesting that conservation measures need to contemplate both forest and grassland ecosystems and socioeconomic distinctions as well.