Locating Log Depots and Forest Roads Using a Weighted-Graph Optimization Algorithm

Sustainable management of commercial forests can be achieved within the limits provided by an optimal, well-designed haul network with low-cost roads and skidding. In this study, a weighted-graph algorithm consisting of nodes (candidate log depots) and links (candidate forest roads) was used to optimize the haul network. The value of each link and node was calculated for thirty six candidate road in harvesting units of an Iranian forestry plan. The analysis of the nodes revealed different skidding costs because of different skidding and winching distances as well as number of logs. Total skidding cost for each node allowed identifying the least-cost depots and designing the links as a support to decisions on road network location. Road cost depends on the length and longitudinal gradient of links, side slope of terrain and unit cost of link construction. In general, the construction cost of each link increased by increasing the link length, side slope gradient and longitudinal gradient. According to our findings, the nodes and links constructed on low slope terrain are the least-costly. The information provided in this paper contributes to the development of knowledge about the usefulness of GIS-based weighted-graph algorithm in determining optimal road network in a forest. Total skidding cost is less for a log depot if there are more marked trees in the related cell. So, if the number of marked trees in the vicinity of the depot is higher and the distance to the depot is lower, the total skidding cost of the depot becomes lower