Salamander abundances in varying northern Michigan habitats.

Abstract

Using a descriptive and comparative approach, we tested the prediction that P. cinereus abundance and condition are explained by factors of soil conditions, ground cover, and number of functional groups in five northern Michigan sites: the Moraine, the Outwash Plain, the Gorge, Pine Point Trail, and Colonial Point old growth forest. We surveyed salamander abundances along four 50-meter transects in each site, examining a total of 176 cover objects. We recorded degree of log decomposition, salamander snout-to-vent length, mass, and the number of functional groups present. We took soil samples, and measurements of soil temperature and leaf litter depth. Statistical analysis showed significant correlation between mean salamander abundance and: soil pH (p=0.000, r2=0.09) leaf litter depth (p=0.001, r2=0.05), log decomposition (p=0.004), and number of functional groups (p=0.04). Due to low r2-values we conducted a multiple regression analysis to check the correlation of salamander abundance with pH, leaf litter depth, and log decomposition and found that together they explain 16% of the variation in P. cinereus abundance (p=0.000). Soil analysis showed that sand was not significant in predicting salamander abundance whereas silt and clay proportions explained 7% of the variation in salamander abundance (p=0.01). There was no statistically significant relationship between the environmental factors examined and salamander condition (g/cm).