Uso de espécies arbóreas nativas e exóticas para recomposição de reserva legal

Abstract

Tropical forests are home to much of the existing ecosystem wealth in Brazil, however, it is often affected by various negative impacts arising from human activities. Current Brazilian legislation allows the use of species with potential for the production of timber and non-timber forest products in the process of recovering forest ecosystems, including exotic species for some situations, such as in the recomposition of the Legal Reserve. In view of this, with a view to analyzing different models for restoring environments in these circumstances, the objective of this work was to evaluate the planting of native species with eucalyptus, as a forest recomposition technique in Legal Reserve areas. The experiment was set up in a complete randomized block design (DBCC), in a 3 x 22 factorial scheme, with four replications. The first factor corresponded to the proportions of eucalyptus used (M1: 75% native species and 25% eucalyptus; M2: 67% native species and 33% eucalyptus; M3: 50% native species and 50% eucalyptus). The second factor was represented by the 22 species studied, among them the 21 native and one eucalyptus. For comparison purposes, two control treatments were also implemented, the first (T1) with 100% native species, and the second (T2) with 100% eucalyptus. At 18 months of age, height (H), diameter at breast height (DBH), crown area (AC) and percentage of dead plants (M) were measured. Furthermore, from the diameter, the cross-sectional area per plant (AS) was calculated. The data were submitted to analysis of variance (ANOVA), and once a difference was verified, the Dunnet test was performed, at 5% error probability, which was used to compare the different planting models with controls T1 and T2. The Tukey test (5%) was also performed for the planting models studied and the Scott-Knott test (5%) for the species. Finally, each group of species, Eucalyptus and native, was analyzed separately by the Scott-Knott test (5%), using the SISVAR software. The treatment with the best plant development was M2. The introduction of the genus Eucalyptus in the restoration of the area did not only negatively influence the growth of the percentage of mortality and the canopy area up to a proportion of 33%, therefore, it is recommended to use 33% of seedlings to reduce the implantation cost of the Legal Reserves recomposition project for maximizing the gain from the sale of eucalyptus wood.