Kevin Allison
Salamander Population Study at Griffy Woods Preserve
BSES Senior Research 2004

Salamanders are recognized as good environmental indicators giving insight into the healthiness of a forest. Amphibians have permeable skin that is susceptible to air-borne toxins, and polluted water affects the soft, gelatinous eggs and the aquatic tadpoles. This population study was conducted on a ridge largely within the Indiana University Teaching and Research Preserve’s Griffy Woods property. Portions of the study area are on lands managed by Bloomington’s Park and Recreation Department. The deciduous hardwood forest in this area is undergoing secondary succession in response to clearing for agriculture during the late 19th and early 20th centuries.

Woodland salamander species have different habitat requirements that may be met in different parts of the study area. In particular, soil moisture generally is lower on south-facing than on north-facing slopes. The study area is an east-west ridge with north- and south-facing slopes. Five 200-meter transects composed of 40 cover objects each were laid out parallel to the ridge along the top of the ridge, the middles of the sides, and along the bottom of the north-facing slope. Because the south-facing slope of the main study ridge was too steep for safe work, the south-facing slope of the parallel ridge to the north was used to sample that habitat. Each fourth cover object was sampled every 7-10 d during September 2 to November 25, 2003. I measured total length of salamanders found under cover objects and then released the salamanders.

I found a total of 109 salamanders during 14 site visits. Five salamander species were encountered: Desmognathus fuscus, Eurycea bislineata, Plethodon cinereus, Plethodon d. dorsalis, and Plethodon glutinosus. There were significantly fewer (p < 0.05) individuals found on middle of the south-facing slope than on the north-facing middle and bottom transects; no other two-way comparisons were significantly different. Plethodon glutinosus was only found on north-facing transects; Desmognathus fuscus was found on north-facing transects and on the bottom transect of the south-facing slope. The remaining 3 species were found on all 5 transects.

In future analyses, I will examine distribution of these species among the transects for signs of habitat preference. I will also analyze salamander counts in relation to rainfall during the study. However, due to the need to moisten cover objects later in the study, and to a change in practice (later in the study, we flipped cover objects before rainstorms to remoisten them), this analysis will be difficult. The data I collected and analyzed in this study will serve as baseline data for salamander populations on forested ridges at the Griffy Woods property. As the forest matures, later surveys may reveal changes in the salamander community.