Monday, August 6, 2007

PS 6-70: Resilience of a terrestrial arthropod community to a catastrophic event

R. Andrew Rodstrom and John J Brown. Washington State University

Epigeal arthropod communities are an integral part of a well functioning ecosystem. This community can often be an indicator of the overall health of an area. When hybrid poplar plantations are harvested, this acts as a catastrophic event within this ecosystem. This project investigated the epigeal arthropod community two years before and two years after the harvest of hybrid poplars in an attempt to document the change in community composition on either side of this planned catastrophe.  Arthropod communities were surveyed primarily using pitfall traps, with some supplemental surveying conducted with light traps to provide a broader image of the overall insect community of this system.  Temperature data was also recorded both above and below ground in pre- and post-harvest communities to try and quantify potential abiotic differences between the communities.  We hypothesized that epigeal arthropod community composition, based on the Shannon-Weiner diversity index, of the post-harvest community would not resemble that of the pre-harvest community.  Our results indicate that there is a strong response to both season and harvest within these communities.  In addition, we show that the post-harvest community quickly recovers to resemble that of the pre-harvest community.  Overall the most common species present in both communities was Calathus ruficolis (Coleoptera:  Carabidae).  This monospecific dominance is most prevalent in the fall, with spring and summer showing greater evenness.  We also show that temperatures mirror the community's quick return to pre-harvest species diversity levels.