| Summary: | The global extinction rate is currently accelerating at an alarming pace. Habitat loss
through the processes of resource extraction, such as forestry are being blamed for much
of the loss of biodiversity. In Canada timber extraction is extremely important
economically, but modern silvicultural practices are impinging upon constituant and
structural features of forest ecosystems, in particular, arthropods. It is important to
characterize both the constituant arthropod species of our forests, and their response to
forest practices in British Columbia.
In this study the effects of clear and partial cutting and shrub removal, and the role of
coarse woody debris were tested in Engelmann Spruce Subalpine Fir (ESSF) and Interior
Cedar Hemlock (ICH) forests. Ground beetles (Coleoptera: Carabidae) were collected by
pitfall traps, and the diversity of assemblages, and the abundance of individual species
were described. Richness was calculated by rarefaction; rank abundance (Whittaker) plots
and the log series alpha were calculated to characterize dominance structure; and the
Shannon-Weiner and Simpson heterogeneity statistics were calculated. Intraspecific
treatment effects were tested with the Kruskal-Wallis single-factor analysis of variance by
rank and non-parametric multiple comparison tests. A dendrogram was generated to
assess forest type and treatment differences.
More than 36,000 carabid beetles consisting of 37 species were collected. A new species,
now called Bembidion jocylyn Kavanaugh and Erwin, was collected. ESSF sites had more
individuals, but fewer species than ICH sites. Logging had a positive effect on diversity
but a negative impact on the total number of individuals. The impact of clear cutting in the
ESSF endured longer than that in the ICH. Partial cutting reduced the abundance of
individuals, but had little effect on overall diversity. Forest species decreased, but did not
disappear in clear cuts; species typical of open habitats increased in clear cuts; habitat
generalists were common in most sites. Most carabid species were either unaffected or
responded favorably to the removal of shrubs: there was an increase in abundance in the
ESSF, and in richness in the ICH. Carabid beetles appeared not to have a relationship to
coarse woody debris, but there were problems with this third study.
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