Japanese Journal of Forest Planning

Show abstractHide abstract

In managing forests for production of wooden logs, evaluation of buyers is important to determine forest management strategies. We surveyed the sawmill industry in the Nagano Prefecture with respect to evaluation of log properties. We asked how log properties affect the mill's opinion during log buying and sawing. Evaluation of rots, surface cracks, and ring shake was universal, whereas log color and ring width were not critical for decisions on purchase and selection of product. This pattern was common to almost all species and timbers. We considered these findings in evaluating strategies for forest cultivation and log production. We grouped log properties into the following two types: strongly influencing purchasing and not critical but affecting log value. Sensitivity of log properties by tree species was as follows: Chamaecyparis obtusa was the most sensitive followed by Cryptomeria japonica. Log properties were not a determinant factor for Larix kaempferi and Pinus densiflora. These results are reflected in the proportion of product type and evaluation of log properties of each species so that differences in evaluation between species result in differences in characteristic sawing practices.

View full abstract

Download PDF (1079K)

This study examined three problems of credibility in offset credits issued by forest-based carbon sequestration projects under the Japan Verified Emission Reduction (J-VER) Scheme. (1) Permanence of carbon sequestration is ensured against emissions by both natural disasters and landowner behaviours, although it is ensured for only 10 years after the end of the period for issuance of credits and is shorter compared with other verified emission reductions (VERs). (2) The criteria for the acceptable level of sequestration uncertainty by the projects might become nominal because monitoring areas or stands do not need to coincide with areas where a monitoring plot is set. (3) Two methodologies for increasing CO_2 sequestration by forest management activities are methodologies R001, a thinning promotion project, and R002, a sustainable forest management promotion project. However, methodology R002 does not necessarily promote sustainable forest management.

View full abstract

We theoretically derived the equation expressing the relationship between the relative yield index (R_y) and relative spacing index (S_r), from the several laws used for the stand density control diagram. The parameters used for the derived equation were collected from reports describing equations, which, in turn, expressed laws used for developing stand density control diagrams for several species and regions throughout Japan. Using these parameters, we examined the variation in the R_y-S_r relationships for several species and regions. Additionally, measurement data were served to confirm the validity of the derived equation. These results show that S_r declines with increasing R_y that the R_y-S_r relationship is expressed by nonlinear curves which vary with the stage of stand development, and that the magnitude of the variation depends on species. This variability of the curve with stand development could be closely linked to the interspecies variation in the self-thinning exponent. The derived equation and collected parameters enable foresters and forest researchers to convert the value of R_y into that of S_r, and vice versa, for many species and regions throughout Japan.

View full abstract

Using the k-nearest neighbor technique, this study estimated the stand volume from systematically sampled forest inventory data and Landsat ETM+ data in the Tohoku region. The root mean square error (RMSE) of stand volume estimates was approximately 120m3/ha, which was about 50m3/ha smaller in comparison with a past study in the Kyushu region where more coniferous plantation forests dominate than the Tohoku region. After applying the atmospheric and topographic corrections, the RMSE of estimates decreased slightly (approximately 2-4m3/ha), however this reduction was small since the ETM+ data used in the present study was recorded with a high solar elevation angle.

View full abstract

Register with J-STAGE for free!