| In this paper, a dynamic model of timber harvesting operations in and a mathematical transportation planning model for the tropical rain forests of Indonesia (TRFI) were developed. The first model is intended to analyze the long term trend of key variables in the TRFI by using the DYNAMO computer simulation language. The second model is developed so that it can be used for estimating the optimum values of road spacing and lowest standard road length.; Using the above developed models for examining the impact of alternative policies in managing the TRFI gave the results from which the following conclusions can be withdrawn: (1) The computer simulation language DYNAMO is a powerful tool for simulating the dynamics of timber harvesting operations in the TRFI. It is capable of incorporating a large number of variables. Also it has the capability of presenting the simulation results both in the form of tables and plots. (2) It is quite likely that at the present speed of timber harvesting and replanting activities in the tropical rain forest of Kalimantan a significant reduction in the area that can be harvested will occur. If true, this means that the sustained yield principle would not be accomplished. The consequences would be felt by logging companies, workers, wood-based industries, wood consumers, and the total economy of the island. (3) Among the six possible alternative policies, Alternative 2 is the policy most likely to succeed. It means that the present level of minimum tree DBH cut (50 cm) and its harvesting cycle (35 years) could be continued but it has to be accompanied by a large increase in the replanting rate. (4) The optimum road spacing and the lowest standard road length vary from one timbershed to another following the change in one or more factors; timber volume per ha, skidding cost, hauling costs on road classes 2 and 3, construction costs of road classes 2 and 3, and forest depth. Variation in the hauling cost, the construction cost of road class 1, and forest width have no effect on the road spacing or the lowest standard road length. (5) The present road density is close to the optimum value of about 6.0 m/ha. (Abstract shortened with permission of author.)... |
