Patterns of abundance and demography: Collembola in a habitat patch gradient

• Published in: Ecography (Copenhagen) 1994-12, Vol.17 (4), p.349-359
• Main Authors: Hertzberg, Karine, Leinaas, Hans Petter, Ims, Rolf Anker
• Format: Article
• Language: English
• Subjects: Animal and plant ecology; Animal, plant and microbial ecology; Animals; Biological and medical sciences; Collembola; Colonization; Cyanobacteria; Demecology; Demography; Fundamental and applied biological sciences. Psychology; Habitat preferences; Habitat selection; Habitats; Metapopulation ecology; Population dynamics; Protozoa. Invertebrata; Size distribution; Species extinction
• ISSN: 0906-7590; 1600-0587
• DOI: 10.1111/j.1600-0587.1994.tb00112.x

The demography and abundance of Collembola in relation to a gradient of increasingly isolated tussocks of Carex ursina were investigated near Ny-Ålesund, Svalbard. The study area was divided into three zones according to tussock density. Ten tussocks were sampled in each zone. In addition, samples were taken between tussocks, which consisted of ground covered with a layer of cyanobacteria. A total of ten Collembola species were found, five of which were chosen for further studies. The Carex tussocks were the preferred habitat for the majority of these species. Only one species, Hypogastrura viatica, was found regularly between tussocks, although at low density. The gradient in tussock distribution was probably an important factor in determining the distribution, abundance and the underlying demographic processes of most species. This was indicated by an increase in demographic heterogeneity with patch isolation. The different species were affected differently, however. Whereas one species appeared to be unaffected by the gradient (H. viatica), two species (H. longispina) and (Folsomia sexoculata) were somewhat surprisingly found to have their highest density where tussocks were furthest apart. Factors other than the spatial configuration of the habitat are probably important in determining the distribution of these two species, indicated by a positive correlation at tussock level between them. In accordance with general hypotheses on the effect of patchiness on population dynamics the remaining two species, F. quadrioculata and Onychiurus groenlandicus, occurred in very low numbers or not at all, respectively, in the zone where tussocks were furthest apart. Their response is probably dependent on their ability to successfully colonise isolated tussocks. We predict that different species specific demographic strategies, and in particular dispersal rates, may account for the observed patterns.