わが国にかつて広範に存在した入会林野は,主に明治以来の政府の入会林野解体政策によって,その多くが解体していった.しかし現在でも,近代的所有形態をとりつつも,実質的に入会林野としての性格を維持している例がかなり存在している.本稿では,財産区という所有形態で旧入会林野を維持し,観光事業に利用している二つの集落をとりあげ,旧入会林野の有効利用の実態を明らかにするとともに,財産区をめぐる諸問題についても考察した.
その結果, (1) 1960年代からの白樺湖・蓼科高原の著しい観光地化の中で,財産区は土地貸付・直営観光事業によって莫大な収益を得,財産区民の生活水準の向上に利用されていること, (2) 観光地化による財産区の事務量増加の中で,人事面において問題を生じていること, (3) 財産区制度の矛盾により,財産管理面で観光地化による新来住民の存在が問題化していること, (4) 財産区収益の増大により,市当局の行政面での圧力が増す可能性が生じてきたこと,などが明らかとなった.

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A forest fire alters the processes of rock weathering, soil erosion, and mass movement. This review focuses a special attention on the soil erosion processes and the controlling variables such as surface runoff, infiltration capacity, and water repellency formed in soil. The literature referred here is mainly taken from United States of America. The results are summarized as follows.
There are some disagreements, among researchers, about the effects of a forest fire on increase in (1) soil erosion rate, (2) the amount of surface runoff, (3) infiltration capacity, and (4) intensity of water repellency. However, a large-scale and intense fire results in the acceleration of raindrop erosion and surface wash to probably cause severe soil erosion. Accelerated raindrop erosion is induced by the removal of litter and duff layers, and increased surface wash is caused by activated surface runoff (e. g., decrease in infiltrationn capacity) which is, in turn, controlled by clogging of soil pores and occurrence of water repellency. In addition, reduced amount of soil organic matter weakens moisture retention in soil, resulting in increased surface runoff and soil erosion.
After a forest fire, mass movement is usually activated due to decrease in tensile strength caused by the death of plant roots for holding the soil. Detailed field investigations on the effects of root systems on geomorphic processes are extremely limited in number.
Rocks exposed to the heat of fires break down by splitting and spalling during the fire. Large spalls have a thickness of a few centimeters and a diameter of several decimeters in size. The spalling is considered to be one of the effective mechanical weathering processes in areas where fires often burn the exposed rocks.
Sediment yield from the intensively burned area, as a whole, is estimated to increase more than several times as compared with the situation before the fire. Sediment yield is generally rapid immediately after the fire, and followed by an exponential decrease towards the pre-burn state (Fig. 1). The “recovery time” of sediment yield is assumed to be within a few years after the fire.
More accurate and systematic studies should be encouraged in the future to investigate the effects of the fire; in particular, a detailed and quantitative description of the intensity and behavior of fires is necessary for the evaluation of (1) fire impact on land surface and (2) subsequent response of the burned site. Furthermore, the subtle changes as well as spectacular changes must be studied in one area to elucidate the interactions among geomorphic processes in the context of “sediment budget” analysis.

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