Anthropogenic disturbances such as harvesting are dominant features of present-day forest ecosystems. Understanding the relative impact of harvesting on native biodiversity is essential for sustainable management of forests. At the EMEND experiment site in Western Alberta, we have experimentally manipulated the amount of standing trees in four boreal forest stand-types to emulate differing intensities of forest harvesting and determine thresholds of habitat availability required by native arthropods. One-hundred forest compartments (approximately 10 ha or greater) were harvested in 1998 and 1999, leaving 100%, 75%, 50%, 20%, 10% and 2% (standard clearcut) standing residual in the stand. Carabid beetles were sampled pre-treatment in 1998, one-year post harvest in 1999 and again in 2000 following any pre-treatment recruitment effects. Overall 45,000 from 31 species were collected. Significant changes in carabid composition were apparent between all four cover classes in each year. Once spatial effects were removed, harvesting by cover interactions were apparent in 1999. These interactions became more pronounced in 2000 after any potential pre-treatment recruitment. Likewise, change in community composition (measured as delta Euclidean distance) between 1999 and 2000 was greater for higher intensities of forest harvest. Harvesting effects were greatest for habitat specialists such as Platynus decentis and Calathus advena.
Species 1: Coleoptera Carabidae Platynus decentis
Species 2: Coleoptera Carabidae Calathus advena
Species 3: Coleoptera Carabidae Pterostichus adstrictus
Keywords: forest harvest, habitat thresholds
The ESA 2001 Annual Meeting - 2001: An Entomological Odyssey of ESA