Abstract
This study focuses on "the distance parameter" that is indispensable component of a spatial interaction model on forest operation activites. Therefore theoretical approaches were discussed for the area distribution of the nearest-access distance from the individual stands within a certain bounded area to the nearest road in a forest road network. In the first, respecting complex boundaries of harvesting units, the probability distribution function of the nearest-access distance was obtained. The parameter z and the coefficient of curvature k derived from this function was shown to be some characterized geographical distance distribution-curves and geographical accessibility points to points. Also, we defined the index F_s to evaluate the distance reflecting the spatial autocorrelation and to take into account both the behavioral and configurational components. The index F_s is given by F_s=(l-p+q)/2, where p is an area ratio of shorter distance than the 1/3 of the maximum of distance and q is an area ratio of longer than the 2/3 of it in the concerned area. By the index F_s, we compared the different types of timber harvesting unit boundaries with forest road nets. Consequently, it could classify the technical difficulties of mechanized harvesting operations for tracts of either regular or irregular shape. In addition, we confirmed that the road net arrangement-index (f-value) being generalized the characteristies of forest roads system was closely concerned with the parameter z or k. That is, f is related to k by the equation f=1+2|k_t|.
