Development of a composite method of evaluating multiple forest functions.

Abstract

We developed a composite method of evaluating multiple forest functions that includes the potential of each function and social requirement. The potential of each function was evaluated by a quantification method using four land description factors. We used the same factors and the same number of categories to evaluate each function and set a weighted value for each factor. Every factor was set in proportion to the range for every function and the weighted sum was equalized for each function. We then attempted to compare the potential of the four functions. A large area including Tokyo and four surrounding prefectures were divided into ten area classes based on the importance of forest functions. Then the importance of each forest function in each class (Degree of Demand) and the importance of each area class in each forest function (Degree of Necessity) was obtained by AHP. The degree of social requirements was obtained by multiplying the Degree of Demand by the Degree of Necessity. From the value for evaluating the potential and social requirements of forest functions, we obtained a new composite value for evaluating the forest functions. Forested areas with high evaluating value are important to planners because of high potential and/or requirements. However, forested areas with low evaluating values are likely to be treated lightly and become neglected. The most important thing for planners, then, is how to manage forested areas with such low evaluating value.