Relation between Oribatid Fauna and Some Environments of Nopporo National Forest in Hokkaido : Acarina : Cryptostigmata : II. Oribatid Fauna in Soils under Four Different Vegetations

Abstract

For the purpose of investigating the relation between the faunistic composition of oribatid mites and the vegetation of their microhabitats, sampling tests were carried out in Nopporo National Forest near Sapporo during ten meteorologically selected seasons in the year 1967. The samples were taken from the microhabitats on and under four different kinds of vegetation, i.e. natural broad leaf forest land (plot Bf), second-growth coniferous forest land (plot Cf), cut-over area with sasa-bamboo (plot Sb) and grassland (plot Gl). The sampling was made by means of a rectangular metal sampler measuring 5×4×5 cm, or of picking up with small forceps. The samples were spread on the bottom sieve of modified TULLGREN apparatus in order to extract oribatid mites.In total, 299.6 (per 1000 cm3 of bark, and 200 cm2 and 19 cm in depth of organic and mineral soil layers) adult oribatids of 47 species from plot Bf, 236.3 (per 1000 cm3 of bark, and 200 cm2 and 17.5 cm in depth of organic and mineral soil layers) adult oribatids of 35 species from plot Cf, 75.1 (per 200 cm2 and 16 cm in depth) adult oribatids of 26 species from plot Sb, 68 (per 200 cm2 and 15 cm in depth) adult oribatids of 4 species from plot Gl and, in sum total, 679 adult oribatid mites of 53 species were collected. The humus horizon of plot Bf had the largest number of species of oribatid mites among all the strate of the four plots. In the grounds under the fo urkinds of vegetation surveyed, the population density of oribatid mites reached a peak during the period from late autumn (LA) to middle winter (MW).