Seasonal invertebrate communities in multiple use jarrah forests. Implications for conservation and management
K. H. Strehlow, J.S. Bradley, J. A. Davis, G.R. Friend, 2004. "Seasonal invertebrate communities in multiple use jarrah forests. Implications for conservation and management", Conservation of Australia's Forest Fauna, Daniel Lunney
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The response of ground-dwelling jarrah forest invertebrates to logging (but not a post-harvest burning) was examined in the Kingston, Warrup and Winnejup forest blocks, approximately 25 km north-east of Manjimup in the south-west of Western Australia. Twenty sites, comprising eight Internal Controls, four External Controls and eight Impact sites, were sampled simultaneously before and after logging. These sites were sampled 18 times (8 pre- and 10 post-logging) over a period of 22 months (May 1994-March 1996). Logging occurred between March and April 1995.
Approximately 500 000 invertebrates were collected from 35 Classes, sub Classes or Orders. The most dominant taxa were Collembola and Formicidae which accounted for 77.6% of the total abundance. Marked seasonal trends were present, with overall invertebrate activity (excluding Collembola) being highest during spring and lowest during winter. The main factors correlated with invertebrate activity were temperature and rainfall. Numerical dominance of taxa changed between seasons and between years. Significant spatial variability was also evident and appeared to be associated with changes in microclimatic conditions and small scale spatial variations in habitat.
Timber harvesting had no significant impacts on total invertebrate abundance and richness. Only 5 of the 35 taxa studied, Blattodea, Coleoptera, Diptera, Hemiptera and Orthoptera, were significantly affected, with Blattodea being the most severely affected. At the level of order, the impacts were only of short duration, with post logging communities resembling those of undisturbed sites after 10 months. Similarly, the impacts of logging on Araneae, Blattodea and Orthoptera assemblages were also only of a short duration. Logged sites followed the same seasonal patterns as control sites in the ordination plots, indicating that seasonal and inter-annual climatic changes appear to be more important determinants of community structure and function of the ground-dwelling invertebrate fauna than a logging event.