The Flambeau River State Forest is a northern temperate forest that was relatively recently glaciated. Because of this glaciation, and the slow natural movement of earthworms, this forest developed with no native earthworms, resulting in an exclusively microbial decomposer community. The addition of earthworms disturbs this existing community, alters the soil structure, and in turn reduces both the native understory and nutrient availability. The Flambeau River State Forest is the site of an existing research project comparing different elements of forest structure in secondary forests, including the creation of large canopy gaps, the addition of coarse woody debris, and the combination of the two. We sampled earthworm density and biomass within the Flambeau site by saturating the ground with mustard, capturing the earthworms as they emerged, and recording their color, length, and species. This sampling was initially done in 2009, and repeated again in 2017. We hope to better understand both how management decisions affect earthworm populations over time, and the effect of earthworms on soil gas exchange.
Results/Conclusions:
Throughout the entire site, we found that epigeic (surface dwellers) composed 45% of the individuals, but only 20% of the biomass. Anecic (deep burrowing) worms composed only 27% of the individuals, but 55% of the biomass. Endogeic (shallow burrowing) worms composed 27% of individuals and similarly 25% of biomass. We found that the overall abundance of earthworms has increased by 44%, ranging from a minimal decrease in density in the gap creation treatment (-2%) to an increase of 98% in the Gap creation and woody debris addition treatment. We found that geographic location strongly affected the abundance of earthworms, as biomass decreased with distance from the river (R2=.55). Greatest proportion of worms across all ecologic groups and treatments was found in the first 5 minutes of the sampling process, suggesting the worms live predominantly close to the surface. Further analysis will model the relationship of biomass with the interactions between distance from the treatment center, woody debris volume (naturally occurring and/or artificially added), soil CO2 flux, distance from the river, and the treatment.