Abundance patterns of soil micro-arthropods at a Pinus pumila scrub in an alpine range of central Japan

Abstract

Seasonal changes in abundances of major soil micro-arthropods were assessed at a Pinus pumila scrub in an alpine range of central Japan during a period with no snow coverage. The total abundance showed a peak in late August, reaching no less than 140 000 m−2, which was comparable to that in an evergreen coniferous plantation in the cool-temperate zone. Collembola was the most dominant group of soil micro-arthropods, comprising about 50% of the total, followed by oribatid mites (Acari [O]) occupying 20%. Annual mean air temperature was no more than 2.1 °C and the daily fluctuation in temperature was less in soil layers. The thickness of the A0 layer reached 9–10 cm and soil organic matter accumulation was estimated to be 45–58 ton dry weight ha−1. The large amount of litterfall and organic matter accumulation in the soil, comparable to those of sub-alpine evergreen coniferous forests, and a lower decomposition rate due to severe environmental conditions, suggest the relative importance of litter processing by soil micro-arthropods such as Collembola and Acari, especially in alpine regions.