Tropical Rain Forest regeneration in an area degraded by mining in Mato Grosso State, Brazil

The floristic composition and structure of vegetation in natural regeneration were studied in a degraded area in Matupa County, Mato Grosso State, Brazil, originally occupied by Tropical Rain Forest. Three plots were used in the shape of a 20 m x 160 m transect, divided into 10 m x 20 m sub-plots, placed parallel to a remnant fragment. Transect 1 was 0-20 m from the fragment; Transect 2, 20-40 m, and Transect 3, 40-60 m from the forest fragment. The total height and diameter at soil height of all the shrubs and tree individuals (height greater than or equal to 0.50 m) were measured to the 5, 13 and 18 months after the area had been systematized and abandoned. Floristic and structural alterations occurred in space and time. The number of individuals, species, families and diversity increased during the time interval studied and decreased with distance from the remnant fragment. These floristic and structural alterations in the community as a whole and in the populations of the most important species, Trema micrantha (L.) Blume and Schizolobium amazonicum Huber ex Ducke, showed the tendency of a succession model by facilitation, where these pioneers would be improving the ecological conditions and thus easing the regeneration of late species. The conservation of the forest fragment in the surroundings was essential for the natural regeneration process of the forest in the degraded area. (C) 2003 Elsevier B.V. All rights reserved.