Seleção e aptidão de espécies arbóreas para a recuperação de áreas degradadas por mineração.

Abstract

Land reclamation can be understood basically by two ways: rehabilitation and restoration. In the first we seek to restore the functions and processes. In restoration, besides the functions and processes we also aim structure and diversity. The restoration of degraded environments by mining has become an indispensable condition to obtain the licensing of mine. This study was developed in the MRN area of bauxite project in the National Forest Saracá Taquera, under the Chico Mendes Institute for Biodiversity, located in the district of Porto Trombetas, Oriximiná municipality, State of Pará. Initially it was analyzed the dynamics of heterogeneous reforestation planted in 1996 at Plateau Saracá, whose monitoring covered a period of 13 years (1996 to 2009). This study aimed to evaluate the planting density, mortality and annual periodic increment (API) growth in diameter and height of 89 species used for restoration after extraction of bauxite. The species were categorized in classes of mortality and increases- of diameter and height. We analyzed the size and ecological fitness, based on mortality and the corresponding increments of diameter and height. The ecological fitness of 69 species during the 13 years of monitoring identified four species classified as unfit, 21 as low fitness, 25 as fair fitness, 16 as good and three as great adaptability. Subsequently, the data was analyzed from a forest inventory and phytosociological aspects of the submontane tropical rain forest considering emerging trees at Plateau Monte Branco, which aimed to adapt, through multivariate analysis, two phytosociological indices involving the same variables of Importance Value Index (IVI ), to compare the results through the ranks of species sampled in three previously established ecological categories: predominantly high, mid and low. The results endorsed the use of factor analysis to extract factors and estimation of factor scores of species. The most appropriate index was the phytosociological horizontal with dummy variable (IFH-VD), obtained by factor analysis, considering the method of principal components, which added a qualitative variable (dummy variable) for each variables involved in the model and selected 81 species key for restoration, while the model without the dummy variable (index phytosociological horizontal - IFH) captured 48. The IVI selected only 10 species in a universe of 745 species. Finally, we analyzed the data from another forest inventory and phytosociological of lowland tropical rain forest with emerging trees at Plateau Almeidas with the goal of building an index also obtained by factor analysis techniques. The model involved six quantitative variables, three inherent of IVI (abundance, frequency and dominance) and three concerning the biomass, commercial value of the timber and the amount of non-timber forest products of the species. For each variable it was assigned a different quantitative qualitative assumed value of 1 for those species having the highest accumulated values amounted to 50% of the total for each of the quantitative variables analyzed. The species were ranked by the proposed index into three categories of priority of phytosociological and socioeconomic (high, medium and low). The results endorsed the use of factor analysis to extract factors and estimation of factor scores. The results were statistically validated for the construction of the index and socioeconomic phytosociological (IFSE) which selected among the 493 species sampled in inventory, 25 key species for restoration. In addition, it was recommended the planting density of these species in the reclamation of mining on National Forest. Conclusively, we analyzed the behavior of 89 species used in reforestation of 1996 properly classified in classes of ecological fitness in relation to the constructed indices (HFI, HFI-VD and IFSE).