Ocupação humana e reflexos sobre a cobertura florestal em um assentamento rural na Amazônia central

Abstract

Rural settlements created to accommodate part of the migrants attracted to the Amazon over the last four decades were included by the Brazilian Environmental Ministry (MMA) among the main responsible for the deforestation in the region in 2008. The impacts of human establishment on the environment are even more dramatic if we consider the degradation process associated to the forest fragmentation and the exploitation of natural resources in the settlements. This work investigated aspects related to the interaction between man and environment in the Uatumã rural settlement project (Projeto de Assentamento Uatumã). The settlement was created in 1987 in Presidente Figueiredo municipality, Amazonas state, Brazil (59o 50’ 14” W and 02o 02’ 24” S). Forests in that region are subjected to logging for about 30 years. We tried to identify aspects concerning the history of its occupation analyzing the relationship between the arrival and establishment of the families at the area and the reflexes on deforestation and forest degradation in its limits. Data about deforestation were obtained from a temporal series of 14 images of the Landsat satellite covering 30 years. This information was related to the data collected through interviews with the settlement dwellers and government agents working at the area, as well as to historic aspects of the development of the region. Data reported in studies of adjacent undisturbed primary forests were utilized for comparison between these variables in order to evaluate forest degradation in the settlement. Being established in a frontier opened by the construction of roadways and the Balbina hydroelectric plant, problems related to soil infertility, economic instability, poor infrastructure and debility of institutional assistance prevented the permanence of many families at their lots. The lumber exploitation that already was established in the region became the main option to those that remained in the area, preventing the total felling of the forest in the settlement. Although there is a great difference between the lots due to the proximity with the roadway that cuts the settlement, the mean forest cover is 80%. The deforestation rates during this period varied in function of local forces favoring the forest conversion and also because of underlying causes occurring in regional, national or global contexts. The exploitation of the forest resources at the settlement reduced the density (476.7 individuals ha -1 , p < 0.001), basal area (23.3 m 2 ha -1 , p < 0.001) and aboveground dry biomass (295.7 Mg ha -1 , p = 0.008) at the study area. A reduction of 12% of aboveground dry biomass was calculated comparing the study area with undisturbed primary forests of the region. Badly planned and managed human settlements within the dense forest of the Amazon open the frontier to dramatic land use changes and exploitation of a vast timber stock, resulting in deforestation and degradation of these ecosystems. Comprehending the subtleties involved in the relationship between man and environment is essential for the development of more interesting and adequate alternatives for the local reality and elaboration of new occupation and development models for the region.