甲府市水源林の形成過程

Abstract

近年，森林の公益的機能に対する一般の関心が高まりつつある。特に森林の水源かん養機能は森林管理とも密接に関係している。筆者は既に東京都水源林及び横浜市道志水源かん養林を対象とした経営計画の変遷，東京都水源林の形成過程を明らかにしてきた。今回は，山梨県甲府市により水道水源かん養のために所有・管理されている甲府市水源林（昭和22（1947）年経営開始）を対象として取り上げた。水源林問題は河川をめぐる上下流の相互関係とも捉えられ，水源林経営問題の解明に当たってはこの上下流の関係成立過程が極めて重要な意味を持つ。そこで本研究では，甲府市水源林の経営前史における上下流の相互関係について明らかにすることを目的とした。分析に当たっては(1)上下流対立の発生と解消過程(2)森林の所有と利用の変遷(3)当時の森林経営計画の3点に着目した。 The Kofu City Forest for Water Supply Conservation has been managed since 1947 in order to conserve water resources. This paper is intended to clarify the process of the formation of Kofu City Forest. Especially, this study pays attention to: 1) conflicts of interest caused by different types of water usage: drinking, irrigation, industry, and so on, 2) changes of land tenure and use of the forest, 3) some forest management plans proposed in the formation process of Kofu City Forest. First, the formation of Kofu City Forest was one of the steps in settling conflicts between Arakawa headwater areas and Kofu City. The forest management for water supply conservation by Kofu City had begun with an action against deforestation in the riverhead of Arakawa river. Since the citizens of Kofu used the river mainly for drinking and industry, they were interested in the safety of the water supply. This interest conflicted with economic activities in the headwater area, such as irrigation, construction of tourist resort, and logging pulp wood. Second, the change of land tenure brought about further conflicts between Arakawa headwater areas and Kofu City. Especially, when the Imperial Forest Agency sold the forest to a shrine and a company, Kofu City protested against the sale. Once the forest belonged to a company, Kofu City felt that the company would readily fell the trees or resell the forest following its own interests. Third, in the formation process of Kofu City Forest, a paper manufacturer who owned the forest made a well-organized forest management plan in 1939. In this plan, the paper manufacturer proposed that a clear cutting system made it possible to harmonize production of wood pulp with water resource conservation. But Kofu City did not accept it and objected to logging.