Migration of Collembola in a patchy environment.

摘要

The output of migrant species and the numbers migrating different distances from a habitat patch was investigated by pitfall trapping Collembola in tussocks of Carex ursinae at a site in Spitsbergen, Norway. The tussocks were embedded in bare soil with a cover of cyanobacteria, and distributed with varying distances between them. In two series of experiments, the migration of Collembola were analysed in relation to species, population size in experimental tussock and distance from tussock. Only Hypogastrura viatica showed a consistent positive relationship between population density and output of migrants. Hypogastrura viatica and H. longispina also had the highest overall output of migrants, and their high mobility can thus counteract the effectsof patch isolation. Migration ability only seems to limit the distribution of Onychiurus groenlandicus. Only a few individuals of O. groenlandicus were captured outside populated tussocks, and the species is generally not present in the most isolated tussocks. Folsomia sexoculata and F. quadrioculata had similar migration abilities, although they have completely different distribution patterns with respect to habitat patchiness. Trials on passive transport were done by net trapping on surface water from snowmelt. This appeared to be a mode of dispersal which primarily affects surface-living species, but did not carry large numbers of migrants and is probably not of great importance.