林道の配置計画について (III) : 林地到達距離による造林作業道の事例分析

Abstract

造林作業道整備の事例調査を行い, 林地到達距離の分布により施業団地の類型化を行った (図1 , 表2)。必ずしもひとつのかたまりとなっていない施業地に対する整備の指標として式 (5) を定義し, 造林事業費の軽減分で作業道が開設できる団地について検討した。その結果, タイプ8 - 10は軽減分で充分開設でき, タイプ4 - 7では配置の仕方, 開設長の削減, 対象施業面積の増大を計る必要があることが判った。式 (1), (3) が成立する範囲では平均林地到達距離が400m以上で式 (8) を満足する施業面積をもつ団地が作業道整備の目安である。

In this report, we wish to report on investigation on working road in TOYAMA Forestation Bureau. It is purpose of this investigation that we establish a method of forest roads network. We think that the distance between road and working place is very imporotant factor to plan the optimum forest roads network. So, we classified working place according to the distribution of distance, as Fig. 1 and Table 2. And we define Index K by equation (5) to plan an appropriate roads network. Index K mean comparing of road length per working area to decrease of average distance between road and working place. If Index K is less than K0 defined equation (5) that is a ratio of road construction cost per metter to decrease cost of planting, weeding and etc. per 100 metter, we can construct a road by decrease of operation cost, as Type 8-10. In working place belong to Type 4-7, it is difficult to construct a road within decrease cost as Table 5, unless shorten a road length, arrange a roads network satisfactority, or increase a working area. If we determined the relation between decrease distance and average distance before road construction as equation (1), and between road length and area as equation (3) in planning place, a road length per working area can be calculated using the equation (7) and minimum area can be calculated using the equation (8). These value are usefull to plan the roads network.