Search Results (3)

Research highlights: We used Dijkstra Algorithm (DA) to define optimal allocation of yards in order to minimize total skid-trail’s distance in the Amazon Forest. DA minimized trails’ distances and associated transportation costs, leading to an even smaller value when the current planning was disregarded and suggesting the reduction of deleterious environmental externalities. Background and objectives: We sought to answer if it is possible to optimize distances and intrinsic costs in the management of Amazonian forests using DA. The objective was to minimize skid trails distances by best allocating yards using DA and to compare four scenarios of forest harvest planning in the Brazilian Amazon. Materials and methods: Tree census data from Gênesis-Salém Farm, state of Pará, Brazil, were used. The yards and roads located by Grupo Arboris (scenario 1) were compared to three alternative scenarios in terms of total skid distance, trails and road densities, and skidding costs for three successive harvests, seeking to minimize total skid-trails’ distance. Alternative scenarios were to keep the number of yards within work units (WU) and place them in the edge of existing roads (scenario 2); keep the number of yards within each WU (scenario 3); and place 23 yards, disregarding the current planning (scenario 4). Results: Total skid-trail’s distance, number of trees above optimal extraction distance and densities of skid trails and roads were smaller in scenarios 2, 3, and 4, compared to the current yard allocation (scenario 1). Scenario 4, with fewer restrictions, reduced skid-trails’ distances by 23%. Harvest costs decreased from scenario 1 to 4 in all three harvest cycles. Conclusions: DA allowed optimized distribution of yards and skid trails and generated efficient results for harvest planning. This reinforces the importance of optimized planning, which establishes satisfactory results in the effort to reduce costs and environmental impact keeping high efficiency. Full article

Several studies investigated soil disturbances caused on skid trails by forest logging. However, there is still a lack of knowledge about the severity and the distance of disturbances along both sides from the trails. The aims of this study were: i) to investigate the changes in physical and chemical properties of soil along the sides of skidding trails; ii) to measure the effects of soil compaction on of maple seedlings growth. Two levels of trail gradient (<20% and >20%), four levels of traffic frequency (3, 8, 15, and 30 passes) and four distance buffer strip zones (0.5 m intervals from 0 to 2 m in distance) on both sides of skid trail edges were analyzed. Each treatment included three replicate plots. In order to investigate the effect of compaction on seedlings emergence and growth, maple seeds were sown after logging. The results highlighted significant changes in physical and chemical properties of soil for each traffic frequency in the closest buffer strip (from 0 to 0.5 m from the skid trail edges). The largest changes in soil properties were identified at 0.5 m distance zones for a slope gradient >20% after 3, 8, 15, and 30 skidding cycles. The highest changes were recorded on slope category >20%. The higher the soil compaction the lower the germination rate, root length, and stem height of seedlings. Full article

Partial cutting is thought to be an alternative to achieve sustainable management in boreal forests. However, the effects of intermediate harvest intensity (45%–80%) on growth remain unknown in black spruce (Picea mariana (Mill.) B.S.P.) stands, one of the most widely distributed boreal species with great commercial interest. In this study, we analysed the effect of three experimental shelterwood and one seed-tree treatments on tree radial growth in even-aged black spruce stands, 10 years after intervention. Our results show that radial growth response 8–10 years after cutting was 41% to 62% higher than in untreated plots, with stand structure, treatment, tree position relative to skidding trails, growth before cutting and time having significant interactions. The stand structure conditioned tree growth after cutting, being doubled in younger and denser stands. Tree spatial position had a pronounced effect on radial growth; trees at the edge of the skidding trails showed twice the increase in growth compared to interior trees. Dominant trees before cutting located close to the skidding trails manifested the highest growth response after cutting. This research suggests that the studied treatments are effective to enhance radial wood production of black spruce especially in younger stands, and that the edge effect must be considered in silvicultural management planning. Full article