Análise da sustentabilidade do manejo florestal com base na avaliação de danos causados por Exploração de Impacto Reduzido (EIR) em floresta de terra firme no município de Paragominas-PA.

Abstract

Damage caused by reduced impact logging has been assessed in 18 plots 1ha each in a terra firme rain forest of the Eastern Amazon (Brazil, Paragominas). Mean logging intensity was 6,3 trees ha-¹ and the resulting commercial volume 21 m³ ha-¹. Logging damage affected 16% of the original stand, 661m² ha-¹ of forest floor and increased by twice the original canopy opening. There was a significant correlation between harvesting intensity and the damage caused to the original stand. This confirms that the benefits of reduced impact logging techniques are maintained only under moderates harvesting intensities. The sustainability of reduced impact logging was evaluated through the calculation of the commercial stand recovery rates in three different scenarios. In the most optimistic scenario, after 30 years, only 50% of the commercial stand would recover provoking a drastic reduction of the harvesting intensity at the second felling cycle. The simulations suggested the stock of commercial trees could be maintained at an technically acceptable level (3-4 trees ha-¹) only within a felling cycle of 40 years and under. the implementation of post-logging silvicultural treatments to stimulate the growth of potential crop trees.