Environmental factors influencing local distribution and activity of the salamander, Plethodon cinereus

TitleEnvironmental factors influencing local distribution and activity of the salamander, Plethodon cinereus
Publication TypeJournal Article
Year of Publication1962
AuthorsHeatwole HFranklin

1. P. cinereus showed seasonal migration both vertically and horizontally in a beech-maple forest floor. When the forest floor was wet, salamanders were in the L layer but as drying occurred they moved into the deeper layers, finally disappearing below the surface of the mineral soil. 2. Microtopography affected the local distribution of P. cinereus. Depressions did not dry out as rapidly as level sites and thus served as refugia during drought. The interior and underside of logs served a similar function. When such places were wetter than the forest floor salamanders moved into them; when the reverse conditions prevailed movement was in the opposite direction. 3. Salamanders did not occupy sites where the moisture content of the substrate was below the absorption threshold for the species, and unless their movement is prevented they are probably never subjected to interstitial relative humidity below 85% (critical level of soil moisture). 4. In the oak-pine-aspen forest temperatures beneath conifer litter and lichens exceeded the probably upper tolerance limit of P. cinereus and excluded salamanders from these substrates. 5. Physical structure of its surroundings influenced habitat selection of P. cinereus. Chunky logs were used to a much greater extent than either fibrous ones or those with a crumbly texture. Also, when moisture conditions were equally favorable throughout the entire forest floor, the L layer was inhabited rather than more compact ones. 6. Plant cover indirectly influenced local distribution of salamanders through its effect on the temperature and moisture content of the substrate. 7. P. cinereus is nocturnal and one of the factors influencing its activity cycle is relative humidity. Salamanders in a gradient moved to the higher humidities, the response becoming more pronounced after desiccation. When body water was low the eccritic level of humidity was greater than 95% whereas it was clearly defined for fully hydrated individuals.