Avaliação da regeneração natural de espécies arbóreas em áreas reflorestadas após a lavra de minério na Amazônia

Abstract

In the Saracá-Taqüera/lbama National Forest, in Porto Trombetas, Oriximiná (PA), Mineração Rio do Norte - MRN, has been mining bauxite since the 1970s. According to the annual production target, an area varying from 120-150 ha/year is deforested. After the mining, the process of forest landscape restoration begins, through reforestation with tree species from the Amazon. The Environmental Monitoring Project, initiated in 1996, aims, among other things, to annually monitor the forest plantations. In this work, the floristic composition, phytosociology and structure of the natural regeneration of trees in the forest plantations promoted by MRN, from 1981 to 1987 and 1992 to 1996, is analyzed. Two permanent plots (25xlO m) were planted in the reforestations each year, and the specific study of natural regeneration began in 2001. A total of 1778 individuals were recorded, distributed among 142 species and 34 families. The families with the highest species richness were Mimosaceae (17 species), Annonaceae (13), Fabaceae (11), Caesalpiniaceae (10) and Melastomataceae (9). The highest abundances were observed in Guttiferae (506 individuals), Melastomataceae (308), Flacourtiaceae (190), Mimosaceae (137), Euphorbiaceae (115) and Celastraceae (100). Combretaceae and Sapotaceae showed only one individual, consequently only one species. The species with the highest abundance were Vismia latifolia (323 individuals), Bellucia grossularioides (234), Laetia procera and Vismia cayenensis (175), Miconia gratissima (109) and Goupiaglabra (100); 45 species (or 31.7% of the total) occurred with a single individual. Vismia Iatifolia and Bellucia grossularioides occurred in all reforestations and systematically presented the highest M values, followed by Laetia procera and Vismia cayennensis, which no longer occurred in only two years of planting. Diametric and altimetric distributions were also analyzed.