Epsilon Archive for Student Projects

Abstract

Carabid beetles are one of the most diverse types of insects and reside in most terrestrial habitats on earth. However, the forests they live in have been heavily altered, with different forest management types emerging in an attempt to extract biomass from the forest but still maintain biodiversity.
I analyzed a data set of carabids caught in pitfall traps from three different forest management types. These were forests managed by clearcutting, retention forestry and those set aside for biodiversity. The data set used was from 240 forest plots split equally between the three forest management types and between the two countries surveyed, Finland and Sweden.
The objective of the report was to analyze if richness, abundance and community composition differed among three forest management types (old clearcuts. retention patches in old clearcuts and set-asides), and if the differences found were uniform between the two countries. The report also compared to what extent species were unique and to what degree there was overlap between the forest management types and countries. With the most common species identified for each of the forest management types and countries. The study also had as an objective to describe the extent to which beetle community composition in retention patches were influenced by trap location and therefore edge effects, these being traps placed either in the middle or at the edge of the retention patches. The collected data was then analyzed and visualized by using box plots, ANOVAs with Tukey’s tests, t-tests and Venn diagrams. I showed that there were significant differences between the forest management types, with retention plots in Finland having the highest carabid beetle richness but the lowest abundance. In the set-asides in Finland, species richness was the lowest. Abundance was highest in Swedish set-asides than in any of the other forest management types. Trap location in retention patches was shown to be insignificant. The community composition of beetles overlapped among the forest management types, 41% of all species were found in all forest management types for both countries and 50% of all species were found in both countries. Only 1% of species were found in both set-asides and old clearcuts, while 10% of species were found in both old clearcuts and retention patches. These overlaps conclude that the different forest management types influence beetle communities in terms of richness and abundance and that the forest management types can be seen as a form of degradation gradient where habitats more similar share a higher percentage of species.