The composition and abundance of microarthropod communities on arboreal litter in the canopy of Cryptomeria japonica trees

In a Cryptomeria japonica plantation, we examined the composition and seasonal abundance of micro-arthropods in communities associated with habitat substrates in the canopy (defined as dead leaves, dead branches, and living leaves) and compared them with those in soil communities. Habitat substrates and microarthropods were periodically collected by the branch-clipping and washing method from the canopy and by the Tullgren method from the soil. Oribatida, Collembola, and larvae of the Chironomidae, most of which are detritivorous or fungivorous, were dominant in the canopy. The dominant oribatid and collembolan families differed markedly between the canopy and the soil. Numbers of all microarthropods per unit dry weight of leaf or per unit area of branch ranged from 4.2 to 11.7g(-1) dry wt on dead leaves, 0.13-0.48 cm(-2) on dead branches, and 1.3-6.4g(-1) dry wt on living leaves. In the soil, the number of individuals per unit ground area ranged from 24000 to 220000m(-2). The total abundances of microarthropods on dead leaves and dead branches were almost constant throughout the year. These results suggest that the arboreal litter characteristic of C japonica canopies is utilized consistently by large numbers of detritivorous and fungivorous microarthropods, and that the decomposition of dead foliage and branches is initiated in the canopy.