THE WOG-WOG HABITAT FRAGMENTATION EXPERIMENT

An experiment to study the effects of habitat fragmentation on biological diversity was commenced in an Eucalyptus forest, in February 1985, at Wog Wog in southeastern New South Wales, Australia. The two hypotheses which are being tested are (1) that habitat fragmentation reduces biological diversity, and (2) that the reduction in diversity is fragment-size dependent. The experimental design consists of three fragment-sizes replicated six times. The sizes are 0.25 ha, 0.875 ha, and 3.062 ha, the two larger ones being progressively c. 3.5 times the size of the smaller ones. Four replicates (12 fragments) were retained as Eucalyptus forest when the surrounding land was cleared for a softwood (Pinus radiata) plantation. Two replicates (six fragments) are controls in an adjacent State Forest. The sampling is stratified into slopes, drainage lines, and inner and outer zones, with samples replicated twice in each stratum. Thus, there are two outer slope and two outer drainage-line sample sites, and two inner slope and two inner drainage-line sample sites. This gives 144 permanent sample sites within the Eucalyptus forest. Following the experimental treatment, a further 44 permanent sample sites were established between the fragments. Aranae, Phalangida, Formicidae, Scorpionidae, Diplopoda, Coleoptera, and vascular plants, are the main groups of organisms involved in the experiment. Mosses and liverworts, breeding birds, small ground-mammals, skinks, and bats, are also being monitored. Monitoring commenced in February 1985. The experimental treatment, i.e. forest fragmentation, took place during 1987. Two years after the treatment there were still no experimental results, because of the inherent delays in sorting and identifying the arthropods, and in establishing and managing the very large database involved. However, the analysis of some pre-treatment data is used to assess the experimental design. This analysis demonstrates the importance of adequate replication in ecological field experiments.