An Economic Benefits Analysis of Low Thinning and Row Thinning Operations：A Study on Two Thinning Cases under Hualien Forest District Office

In order to consolidate the timber supply for the domestic consumption, and to provide the resource stock of different sizes of woods, the Forestry Bureau of the Council of Agriculture plans to conduct certain level of forest thinning in Timber Management Area of National Forest. If the forest thinning is not conducted, the plantation forest will not be able to generate large-diameter woods, and it will restrict the usefulness of timber. So the Forestry Bureau commands the Forest District Offices to conduct forest thinning in accordance with their forest district management plan. Forest District Offices however would face many challenges if they are going to conduct thinning operations. These challenges include how to conduct thinning, which forest thinning method should be used and to decide the best timing for thinning, etc. In order to make the retained trees after thinning to provide the maximum benefits, it is an important topic to establish a proper procedure and method to evaluate the benefits generated by different thinning methods.ryptomeria (Cryptomeria japonica) plantation at Hualien Forest District Office is more than30 years. The forest stand is dense. Hualien Forest District Office decides to conduct forest thinning to promote the growth of retained trees. In 2008 Hualien Forest District Office conducted forest thinning on both sides of Jeisui logging trail in the 27th Forest Districts of Yuli Business District. For the forest above the logging trail, low thinning method was utilized and the thinning intensity was 28.6％. For the forest under the logging trail, row thinning method was utilized and the thinning intensity was 40％. Based on these two thinning cases, this study analyzes and compares the economic benefits of low thinning and row thinning methods.his study uses the size-class distribution to estimate the state of stand before and after thinning operation. This study then uses the stand growth model developed by the Experimental Forest Bureau of the National Taiwan University, and modifies parameters to fit the stand growth in Plantation Forest of Hualien Forest District Office. And lastly this study uses the estimate of the future growth of the timber volume to estimate the net present value of low thinning and row thinning under a single timber rotation.ased on the estimate of this study, the net present value (NPV) of the net benefits of low thinning is -456,218 NTD dollars, the NPV of the net benefits of row thinning is -1,206,861 NTD dollars. The sale value of thinned timber is below the thinning cost. This study compares the NPVs of four different cases, such as unthinned stand and low thinned stand above logging trail, and unthinned stand and row thinned stand below logging trail, under the assumptions of 87.36％ timber harvest rate, 70% timber utilization rate, 0.7％ real discount rate, 1.08％ inflation rate, and the constant level of the real prices of timber. Based on the estimate of this study, for all four cases the NPVs increase along with the increases of the timber age. And the NPV of unthinned stand is higher than the NPV of the thinned stand. Moreover, the NPV of low thinned stand is higher than the NPV of row thinned stand. Based on a single timber rotation, the NPV per m3 of unthinned stand is higher than the NPV per m3 of thinned stand. And the NPV per m3 of row thinned stand is smaller than the NPV per m3 of low thinned stand.ased on the results of this study, it is therefore concluded that the plantation forest of Hualien Forest District is not appropriate for thinning. Thinning will result in the decrease of the NPV of the forest under one timber rotation, and the decrease of the NPV of row thinning is higher than the decrease of the NPV of low thinning. If Hualien Forest DistricIt decides to conduct forest thinning in the future, it is suggested that it should set up sample plots, to gather stand data before thinning, and to measure he real thinning area. Evaluation without sample plot data and real measure of thinning area will result in evaluation error.