THE EFFECTS OF ROAD DESIGN AND HARVEST INTENSITY ON FOREST DAMAGE CAUSED BY SELECTIVE LOGGING - EMPIRICAL RESULTS AND A SIMULATION-MODEL FROM THE BOSQUE CHIMANES, BOLIVIA

Selective harvesting in tropical forests has been shown to cause considerable damage to residual trees in stands that have relatively high densities of commercial trees. To complement existing studies, we measured forest damage caused by the selective harvesting of mahogany (Swietenia macrophylla), a very low density species in the Bosque Chimanes, Bolivia. Secondary damage along main roads and skid trails accounted for most of the damage measured in the study site. Total damage was low (4.39% of the study area), but results from our simulation model suggested that damage could be decreased by up to 25% by requiring main roads and skid trails to be linear. We used our simulation model to investigate the relationship between harvest intensity and forest damage. At low harvest intensities, most forest damage occurs from the construction of main roads. As harvest intensity increases, secondary damage from skid trails and tree felling comes to dominate forest damage. Overall, less damage will result to the forest for a given harvest volume if the harvest area is reduced and harvest intensity increased. Additional benefits to increasing harvest intensity are that re-entry into the logged site can be delayed, allowing the forest more time to recover, and regeneration of light-demanding species such as mahogany can be enhanced. The main impediment to increasing the harvest intensity in selective harvesting operations in Latin America is the lack of international markets for lesser known species, although there is some local and national demand.