Abstract
The present paper deals with the seasonal variations of the population density and biomass of macro soil animals, which exceed 2mm. in body length excluding mites, springtails and enchytraeides, in forage swards, Sapporo. From May of 1965 to April of 1967, twice a month, six replicated soil samples (25 sq.cm.×30cm. deep) were taken, and numbers of larvae or adults were counted and their wet weight was measured. The population density and biomass showed seasonal variations, namely they were large in autumn (September-October), and small in winter (December-March). The macro soil animals collected were classified into 22 groups, covering three phylla and 13 orders. Among them, the groups with the population density of over 2% of the total individual number were: Oligochaetes (74.0%), Formicidae (7.0%), Scarabaeides (3.4%), Elateridae (2.3%), Aranea (2.5%) and Diplopoda (2.2%). Each of these groups showed more or less the peculiar seasonal variation, but in most case the density was large in autumn and small in winter. During winter, Oligochaetes occupied the majority of total individual number and biomass.
