A tomada de decisões conservacionistas baseadas em informações sobre a biodiversidade em empreendimentos hidrelétricos na Bacia Amazônica

Abstract

Environmental impact studies (EIAs) are used to understand the potential impacts of a construction and to suggest whether the project is viable under the environmental point of view. However, few ecological tools of analysis are currently used for this conclusion. One of them is the legal requirement for the stabilization of the collector curve, which has been strongly accepted by the consultants and employees of Ibama (Brazilian Institute of Environment and Renewable Natural Resources) because it is well known and used by some researchers in the world to analyze EIAs. However, the assumptions of the analysis are rarely found in real decision-making situations about hydroelectric dams. The main factor that prevents its use is the impossibility of performing random sampling in large areas of difficult access. In some spatial scales, the absence of randomization is not relevant, but this is not the case with hydroelectric projects in the Amazon basin. If this assumption can not be met, decision-making based on the collector curve is not informative about the validity of the sampling. The species richness measured by the collector curve has had little applicability by conservation biology. Knowledge of the elements of biodiversity present is considered more relevant today and, therefore, sampling in all area of inference is a more useful recommendation, since knowledge of less rare species can give more support in decision making. Complementarity is the current paradigm of conservation biology that relies on some widely used algorithms and analytical tools in the world. Choosing conservation targets that should be considered relevant is a critical part of this process. Initially, we considered the list of targets presented in the EIAs, those required by the legislation, and also those listed at a workshop of researchers on hydroelectric dams in the Tapajós River basin. The selection of priority targets was made in this study through the spatial overlap of these initial targets with all the dams built and planned in the Amazon basin. The analyzes indicated that only aquatic targets were threatened by dams, and the use of a high number of targets may lead to the erroneous conclusion that there is little impact on the targets analyzed. The Tapajós basin is planned to receive the greatest investment in construction of new dams by the current proposal of the Brazilian Ministry of Mines and Energy. Using only the targets that were selected in Chapter 2, a simulation of dam combinations was made by contrasting the hydroelectric potential and the degradation in biodiversity that each potential combination could cause. By means of the Pareto frontier analysis, some arrangements of dams have resulted in “win-win” situations, showing that energy production can be compatible with environmental preservation, but these best combinations are not the current government's proposal. One of the most efficient points showed that it is possible to produce 78% of the potential electricity with a loss of 21% of biodiversity compared to the current government proposal. All the results were strongly influenced by the choice of the analyzed targets and these should be investigated more thoroughly before hydroelectric decisions are made in the basin.