Abstract
For an improved mechanized methods of logging, one of the most important issues is to consider whether skidding roads are systematically arranged in harmony with terrain features or not for a certain logging area. To realize such purpose, the characteristics of these road nets were analyzed theoretically and quantitatively by using some assumed geometrical models and field data practiced in felling sites. In this paper, we confined the skidding road network with tree structuers which was used in distributed hydrological modelling. Consequently, applications of stochastic branching process theory to skidding road networks were clarified. The distribution of bifurcation in these road nets was expressed by the relationship between the ratio of the numer of paths as segment which links origin to destination (t_j) and the ratio of the cumulative bifurcation points (g(t_j)). Namely, it could be expressed as an exponential equation by the α-th power of t, and where the exponent a is about 0.5-0.6. Also, the index (f-value), which described the arrangement of these road nets for a certain logging area, might be changed by the ratio of the minimum convex covering of the area within elongated skidding road nets per the whole logging area(k). From this concern, theoretical calculations were explained that the f-value was minimized when the ratio k was about 0.7. The minimum of the f-value, which was spontaneous skidding road nets with randomly distributed as tree structure, was about 1.57.
