DEFINING SOIL MACROFAUNA COMPOSITION AND ACTIVITY FOR BIOPEDOLOGICAL STUDIES - A CASE-STUDY ON 2 SOILS IN THE WESTERN AUSTRALIAN WHEAT-BELT

In Durokoppin reserve and surrounding farmland, part of the central wheatbelt region, pitfall trapping and mapping of soil macrofauna activity were used to define the extent of soil macrofauna activity in these two environments. This type of study is a necessary precursor to determining the significance of certain invertebrate activity in soil modification in these habitats. The relative merits of the two techniques in determining the extent of soil macrofauna activity is assessed. The soil macrofauna groups identified by mapping and pitfall trapping as making a substantial contribution (in terms of relative abundance and activity) in all habitats were, in descending order, ants, spiders and scorpions (wandoo woodland only). In general there was good agreement between the two techniques in identifying the major species and trends in species composition between habitats, but mapping failed to identify the rare or cryptic species. Mapping more accurately identified the resident species in each habitat compared with pitfall trapping. Pitfall trapping data indicated that foraging activity of most soil macrofauna was depressed over winter, except for beetles, and was higher in the spring and summer sampling periods. However, mapping revealed a more constant level of soil macrofauna activity, especially for ant nests. It is argued that the two approaches complement one another and that each has value in interpreting the effects of soil macrofauna activity on soil properties in further studies. The discussion is based on the results of a study carried out in the Kellerberrin area of Western Australia.