O bosque de mangue do estuário do rio Timbó, estado de Pernambuco, Brasil: características estruturais e vulnerabilidade da área frente às tensões antrópicas

Abstract

The studied area belongs to the basin of river Timbó. It is included in the group of smaller coast line basins of Pernambuco and it is placed between the south latitudes 7º 50’ and 7° 54’ S and the west longitudes 34º 53’, and 34º 55’ in the Metropolitan Region of Great Recife - in the districts of Paulista, Abreu e Lima and Igarassu. The composition and the structural characteristics of the swamp were evaluated in tem sections divided a long the right and the left banks of the river; from the river to the interior of the mangrove, using the parcels method. The antropic impacts on the mangrove were also researched through photons and the application of a advised matrix of environmental impacts (check list).The diversity and the quantity of a solid wastes found in the interior of the swamps were also considered. The research showed that there are 3 typical species of mangrove area. The are found in the sections (Rhizophora mangle, Laguncularia racemosa and Avicennia schaueriana); Rhizophora mangle is the predominant specie, both in terms of frequency and in terms of density. In the sections of the right bank side of the river the values of DAP varied from 7,31 to 16,08 cm, and the average height varied from 2,88 to 9.77 m, the basal area varied from 7,21 to 17,07 m². ha-¹ and the density from 760 to 12.000 ind. ha-¹. In the left bank the DAP varied from 4,9 to 8,51 cm; the average height from 3,69 to 9,91 m, and the basal area from 5,69 to 11,65 m². ha-¹ and the density from 840 to 6.140 ind. ha-¹. These results suggest that the mangrove is structured and shows an exuberant thicket. The totality of catalogued impacts in the area showed however, that the environment is very vulnerable to the antropic factors. It was seen that these tensions are more intense and more varied in the borders of the woods. In the right bank of the mangrove, it is pressured by the urban development; and in the bank side, this tension happens more intensity next to the mouth, mainly due to the leisure and agricultural activities (including the construction of fish farms). The main antropic factors in the area were: landfills, leisure activities, construction of buildings, roads, transmission lines, piers, land movement, river walls, hostels, erosive processes, tourism, fish farms and forest fires. The presence of solid wastes was observed in the interior of the mangrove in all sections studied. The Plastic materials were more obvious both in terms of diversity and weight. The total of garbage that may be found in the interior of the mangrove is about 1.236,90 tons.