Session Information
| Session | Poster Session | | Date | Monday (2008-04-07) | | Time | 5:00 PM - 7:00 PM | | Room | Grand Terrace |
Presentation Information
| Presenter | Jodi Forrester | | Title | Influence of forest management on spatial patterns of exotic earthworm abundance in a second-growth northern hardwood forest | | Affiliation | University of Wisconsin - Madison | | Authors | Jodi Forrester, Erika Latty, David Mladenoff | | Keywords | Earthworms, Exotic species, Forest management, Northern hardwoods | | Presentation Type | Poster | Abstract:
We have initiated a replicated, long-term, large-scale field experiment designed to test the effects of old-growth structural features on the biodiversity, productivity and nutrient cycling in a second-growth northern hardwood forest in northern Wisconsin. Based on recent studies from other north temperate forests, we recognize that the presence of exotic earthworms may also significantly influence ecosystem structure and function. The aim of this study is to spatially assess the degree of invasion of non-native earthworms within our long-term study site and to measure the response of earthworm abundance to experimental forest management including the creation of canopy openings and addition of coarse woody debris. We surveyed earthworm populations using the liquid extraction technique in spring 2006, 2007 and fall 2007, on 3-6 quadrats per 30 plots. Pretreatment surveys indicated that epi-endogeic, endogeic, and anecic ecological groups occur within the site. The biomass and density of red-bodied (primarily Lumbricus spp.) earthworms are significantly greater than grey-bodied (primarily Aporroctodea spp.) throughout the site (both p<0.001). The eastern half of the 280 ha site has a significantly higher earthworm density (211 vs. 109 earthworms/m2, p=0.0001) and biomass (5.1 vs. 2.4 g/m2, p=0.001) than the western plots. Earthworm abundance was found to be positively related to soil organic matter and clay content, and the C:N ratio of the forest floor; but negatively related to litter depth, and forest floor nutrient content (N, P, Ca). Immediately following the creation of canopy openings and addition of coarse woody debris in January 2007, earthworm abundance increased significantly within canopy openings (p=0.03). As this is an ongoing experiment, we expect the fall 07 and spring 08 sampling to document further increases. Other analyses are investigating patterns between earthworm composition, overstory vegetation and microclimatic variables associated with the spatial location within the canopy opening. Accounting for this additional source of spatial heterogeneity within the research site is important to the interpretation of the results of our experimental treatments. |
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