Projeto Replanta Guandu: análise dos resultados uma década após o plantio

Abstract

The watershed of the Guandu River is extremely important for supplying water to the ten million inhabitants of the metropolitan region of Rio de Janeiro, in addition to making a considerable contribution to the supply of electricity in the state. The degree of serious and progressive environmental degradation of the surface in the basin impacts the quality of its waters. In 2007, the Guandu Basin Committee implemented the Replanta Guandu Project with the proposal of environmental revitalization for the purpose of water production in an experimental and demonstrative way in five of its fifteen municipalities. In this context, the objective of this study was to evaluate the events proposed by the Replanta Guandu project, focusing on the reforestation subprogram in six areas of the basin, in order to identify guiding indicators for new initiatives to revitalize basins in the design of Green Infrastructure. Forest inventories were carried out in six areas from the subprogram in 2019, in Seropédica (Area 1: DCUM Army; Area 2: Embrapa Agrobiology) and Rio Claro (Area 3: Morro da Usina de Reciclagem; Area 4: São Benedito Farm; Area 5: Morro do Estado; Area 6: Morro do Alambari). Areas 1 (8.7 ha), 2 (8.8 ha), 3 (3.6 ha), 4 (4.6 ha), 5 (2.4 ha) and 6 (6.9 ha) had planting carried out between 2007 and 2008. In field surveys, 7 to 13 sample units (su) were randomly allocated, depending on the size of each area. In each ua, the following variables were obtained: geographic coordinates, number of individuals, grass and canopy cover, average height of individuals, Shannon diversity and Pielou equity. Botanical identification was performed for all measured trees. The assessment of reforestations was based on resolution nº 143/2017 proposed by INEA, based on the Rapid Ecological Diagnosis - DER, in which the following seven parameters were considered: density; percentage of zoochory; canopy cover; equity; wealth; average height and grass infestation. Furthermore, using the inverse interpolator of distance weighted by exponent 2, the seven parameters obtained, the relief, and the normalized difference vegetation index (NDVI) were mapped in all areas. The results show that Areas 2 and 4 meet the final grade of the DER, with grades equal to 8.0 and 8.99, respectively. Areas 1 and 6 presented a concept of 8.07, however, they presented a critical value for Pielou equity and grass infestation, respectively. Area 5 presented the highest threats among the evaluated areas (5.64), related to weed competition, deforestation and occupation. The proportion of zoochoric species was above 50% in all areas, demonstrating the interaction between fauna and flora in reforestation. Diversity, density, and canopy coverage are the most important parameters that enable Green Infrastructure and water production. Despite the intense performance of disturbing factors to the establishment of reforestation both in the lowlands and in the mountains, it showed resilience by surviving twelve years after planting with an average of 7.95 of the six units.