Abstract
The structure of small rodent communities, in both natural forests and young plantations, in the Asahikawa region of Hokkaido, Japan, in relation to the effects of long-term and large-scaled forestry, was analyzed using census data spanning the 31 years from 1962 to 1992. Rodent communities in both natural forests and plantations consisted largely of four species : Clethrionomys rufocanus, C. rutilus, Apodemus argenteus, and A. speciosus. Clethrionomys rufocanus was found to be dominant in both habitats, however the relative abundance of species differed significantly between habitats. Although the dominancy of C. rufocanus was most obvious in forestry plantations, the proportion it contributed to the community decreased during the 1980s. Conversely, Apodemus species have increased in both habitats over the same period. Rodent species diversity has increased in the last decade. The decline in the proportion of C. rufocanus has occurred in parallel with the decrease in the area of land under forestry plantation, which is the preferred habitat for C. rufocanus. These findings indicate that monocultural habitats, such as forestry plantations, may support super dominant species such as C. rufocanus, which results in an impoverished rodent community, in terms of species diversity.
