Protura, Pauropoda and Symphyla in Norwegian coniferous forest soils: abundance and vertical distribution

Few studies exist on the quantitative occurrence of Protura, Pauropoda and Symphyla in Scandinavia. Soil samples were taken in spring and autumn in two coniferous forest sites near Oslo: one below and one above the marine limit. At each site, 7 different vegetation types were sampled, from poor pine forest to rich spruce forest. Protura occurred in all vegetation types, with maximum abundance in a Vaccinium pine forest (55 400 m super(-2), corresponding to 63% of the Collembola density). Pauropoda and Symphyla were found only in the site below the marine limit. Maximum abundance of Pauropoda (4 100 m super(-2)) was found in the richest soil, while Symphyla were most abundant (2 700 m super(-2)) in a Vaccinium pine forest. Pauropoda and Symphyla were absent in the two poorest pine forest soils. Protura were most abundant in the 0-3 cm layer in raw humus soils, but had a deeper maximum (most often 3-6 cm) in richer mull humus soils. Pauropoda and Symphyla occurred predominantly below 3 cm depth. All groups occurred down to 12 cm depth, but they can obviously go deeper. There were often considerable differences between spring and autumn densities of all three groups. It seems that the abundance of these groups may have a local character. Vegetation and soil types can only explain part of the variation in their abundance.