Abstract
The present study deals with the ecological distribution of the lumbricid earthworms which were hand sorted from 91 localities in Hokkaido during 1965-1969. The lumbricids were often found together with megascolecids, the other family of megadrilid earthworms in Hokkaido. Though the former were dominant at many of the sampling localities, it was noted that when the land was cultivated and cropped the latter increased in number, even though the land was located at rather high altitudes. From seashore to tops of high mountains, the following species of Lumbricidae ranged: Allolobophora japonica MICHAELSEN (A and B forms), A. caliginosa (SAVIGNY), A. rosea (SAVIGNY), Bimastus tenuis (EISEN), Eisenia foetida (SAVIGNY) and Dendrobaena octaedra (SAVIGNY). Each species had its own peculiar habitat, but a little similarity in habitat (AGRELL INDEX) was observed between A. japonica (A) and D. octaedra. The sampling localities were divided into 13 types in reference to land utilization, and high similarities in the composition of the Lumbricidae (RENKONEN INDEX) were measured at two combinations: broad-leaved forests and secondary vegetations after the destruction of the natural forest; grasslands and pastures. The relationship between species composition and vegetation types or the soil types are also discussed.
