丹沢山地長尾根での森林皆伐後のニホンジカとスズタケの変動

抄録

Longterm changes in the population dynamics of sika deer (Cervus nippon) and suzutake (Pseudosasa purpurascens) were surveyed between 1972 and 1980 in the Tanzawa Mountains, central Honshu, Japan. The density of sika deer decreased from 47/km^2 in 1972 to 18/km^2 in 1979, in conjunction with a decrease in the area size of suzutake stands of less than 10 years of age which supply abundant forage for sika deer. The suzutake population, the main diet of sika deer in winter, retreated from the lower area of around 500m in elevation in 1973 to the higher area above 1, 070m in elevation in 1980. In addition, the amount of biomass at the top of the plants became extremely small during this period. Those changes were probably caused by heavy feeding pressure of the high sika deer density that was induced by the increase in area size of clear-cut forests during the period of 1963-1971. From the above, it could be asserted that clear-cut operations should be regulated in size and distribution for the stabilization of sika deer populations at a lower level density.