Avaliação econômica do manejo florestal em floresta de terra firme na Amazônia brasileira com aplicação de silvicultura pós colheita.

Abstract

This study aimed at evaluating the costs of different post-harvesting silvicultural systems applied to a terra firme forest in the Brazilian Amazon. It was carried out in the Rio Capim Forest Management Unit, which belongs to Cikel Brasil Verde Madeiras, located in the Municipality of Paragominas, Pará state. The experiment was established in 2005, one year after Reduced Impact Logging (RIL). Total experimental area is 700 ha where seven treatments were established (100 ha each) with four replications (25 ha each), randomly distributed in the experimental area. The following treatments were applied: T1 - RIL + classical liberation thinning and climber cutting; T2 - RIL + modified liberation thinning and climber cutting; T3 - RIL + climber cutting; T4 - RIL + planting commercial species in gaps, keeping and tending natural regeneration seedlings of commercial species and climber cutting; T5 - (T2 + T4); T6 - RIL; and T7 - unlogged forest (control). Productivity of was recorded during liberation thinning and climber cutting activities (average of 115.7 assisted individuals/day and 9.2 girdled individuals/day). Planting and selection of natural regeneration in gaps seedlings had a productivity of 10 gaps/day. Mean productivity of monitoring girdled individuals was 140.1 individuals/day for all treatments. Productivity of monitoring and cleaning gaps was 15.4 gaps/day. The estimated total cost for 30 years after harvest, for each treatment, was: T1 (R$ 123,28/ha); T2 (R$ 75,34/ha); T3 (R$ 117,54/ha); T4 (R$478,61/ha); T5 (R$ 436,07/ha); T6 (R$ 124,86/ha); and T7 (R$ 202,01/ha). In spite of differences on total costs between treatments, the investment analysis showed that all treatments (T1, T2, T3, T4, T5 and T6) are economically viable at the end of a 30-year cutting cycle with a new harvest, considering a 12% bank rate a year, with NPL > 0 and BCR > 1. The most efficient post-harvesting system, considering only economical aspects, was T2, because it had lower costs and higher NPL and BCR.