Soil Mesofauna from Litter Bag Set in Riparian Areas of Rivers Flowing into Lake Inawashiro

Abstract

 It has been reported that diverse macroinvertebrates play an important role on litter decomposition in the vegetated area of a river. To obtain basic biological information on litter decomposition in the vegetated area of a river flowing into Lake Inawashiro, this study investigated the composition of the soil fauna involved in litter decomposition in neutral and acidic rivers. A survey of the soil mesofauna was conducted using the litter bag method. Litter bags with two mesh sizes （0.2 mm and 2 mm） were placed in riparian areas covered with reeds of two rivers （the neutral Nagase River and the acidic Sukawa River） flowing into Lake Inawashiro. The litter bags were removed after 3–12 months. Litter decomposition was in progress because, consistent with previous reports, the total carbon content and carbon/nitrogen ratio in the litter decreased, and the reed residues in the litter bags were softened and disintegrated into pieces, at 12 months after placement. In the acidic riparian area （Sukawa River）, the number of collected taxonomic groups was higher in the litter bag than in the surrounding soil. In the litter bag and the soil, enchytraeids and oribatids were abundant. The collected enchytraeids were assignable to five genera. To understand the role of the soil fauna in litter decomposition, detailed investigation of the physiochemical properties and more comprehensive sampling are required.