There are many related studies; however, almost all of them focus on higher taxonomic tendencies, ignoring a difference in the reaction for each species. In this study, we measured relative basal area (RBA) as the index for invasion of broad-leaved trees into eight Larch plantations, and investigated the relationship between RBA and composition and abundance of oribatid mites community. As a result, we found 49 families, 60genus, 89 species, 24,368 adult and larvae and nymphs, 56,364. The degree of invasion of broad-leaved trees did not affect significantly total abundance and number of species for oribatid mites observed. While, those measurements significantly correlated with the total amount of litter, including conifer and broad-leaves. We also found that there are many oribatid mite species showing habitat preference relating to a kind of litter.

• Aino Ota(Yokohama National University)
• Motohiro Hasegawa(Kiso Experiment Station, Forestry and Forest Products Research Institute)
• Masamichi T. Ito(Surugadai University)