Earthworms, Salamanders, Forest, Slope, Distribution, Abundance
Brunges, Hunter J. and Dunn, James, "The Effects of Invasive Earthworm Species on Salamanders in the Grand Valley State University Ravine Ecosystem" (2015). Student Summer Scholars Manuscripts. 145.
Earthworms are an invasive species that are causing ecological damage to northern forest ecosystems. The disruption to soil nutrient cycling and litter decomposition can negatively impact organisms that live within the leaf litter, such as salamanders. To test this hypothesis, we sampled earthworms within three ravines at thirty-six sites using the mustard extraction method. We surveyed salamander populations on two dates in 2015 at each site using cover boards. We also collected data on slope aspect, altitude, soil moisture, leaf litter coverage, canopy cover, and coarse woody debris at each site to determine their effects on earthworm and salamander populations. Unexpectedly, our results show that total earthworm populations did not decrease salamander abundance. However, epigeic earthworms in north facing, low elevation sites did have a negative effect on salamanders. We also found that anecic earthworm species had a negative impact on leaf litter in south facing, low elevation sites. Using a GLIMMIX model, we found that epigeic earthworms had a negative effect on salamander populations, while anecic earthworms had a positive effect on salamander populations.