Area disturbed and residual stand damage following logging in a Bolivian tropical forest

Abstract

The area disturbed and damage to the residual stand caused by planned diameter-limit logging was assessed in a tropical humid forest of Bolivia and compared with disturbance and damage reported in other studies in the neotropics with similar harvesting intensities. The forest was logged by a private company under a government concession. The harvest incorporated many reduced impact logging practices including pre-harvest tree inventories, planned placement of roads and skid trails, vine cutting, and directional felling. A total density of 4.35 trees/ha and 12.1 m 3/ha of wood were harvested. It was estimated that logging disturbed 45.8% of the stand including 25% ground area disturbance in the form of skid trails, logging roads, and log landings and an additional 25% in canopy openings due to tree felling. On average, 44 trees were damaged for every tree extracted including 22 trees killed or severely damaged, 6 of them commercial species. The most common types of damage included uprooted stems, stem wounds to the cambial layer, and bark scrapes. Road width was found to be a significant factor determining the number of trees damaged along logging roads but not along skid trails. Damage to trees sustained along skid trails was found to be significantly less than the damage incurred along logging roads. Residual damage in felling gaps was positively related to the diameter-at-breast-height of the harvested trees. Comparisons with other planned operations revealed a higher percent ground area disturbed and a greater felling gap area per tree extracted. Higher ground area disturbance was mostly due to the greater area in skid trails, many of which appeared to be unnecessary. Larger felling gap sizes appeared to be at least partially attributed to the larger size of trees harvested relative to those in other forests. The results of this study suggest that reduced impact logging practices may also need to be accompanied by close supervision of field personnel, monetary incentives and/or disincentives to loggers, and post-logging site inspections to be implemented properly.