Resource partitioning among six species of the salamander family plethodontidae

Resource partitioning is a means by which similar species divide community resources. This may occur in terms of spatial, temporal, or trophic partitioning. Six species of salamanders (Desmognathus aeneus, Q. ochrophaeus, Q. fuscus, Q. monticola, Q. guadramaculatus, and Plethodon glutinosus) occur sympatrically in Cherokee National Forest of southeastern Tennessee in sufficient abundance for quantitative studies. This study was designed to investigate temporal and spatial partitioning among these six species. Thirteen microhabitat and five activity variables were measured in the field. In addition, salamanders found during the microhabitat sampling were collected, aged, and measured. Due to problems with correlations and distributions, the microhabitat data set was reduced to eight variables; the activity set to three. These data sets were analyzed using a stepwise multiple discriminant analysis. Differences in size are often cited as facilitating food partitioning. For this reason, a size variable, snout-vent length, was added to the microhabitat data set to determine its effects in species separation when considered with the microhabitat variables. The multiple discriminant analysis indicated that in both adults and juvenile salamanders, separation of microhabitats was primarily a function of the mean distance of each species from water. However, the microhabitat variables were only able to place approximately 50% of all individuals into the correct species. With the addition of a size variable to the microhabitat variables, approximately 80% were correctly predicted. Temporal partitioning apparently did not occur, as only about 40% of all observations were correctly predicted. This study indicates that if food size is related to body size, then resource partitioning among the six species of salamanders apparently has both a trophic and a spatial aspect. This follows from the fact that the microhabitat and size variables taken together provide the best method of separating species. This is thought to be a result of physiological constraints related to water loss limiting the extent to which habitat partitioning can occur. Other factors that may have important effects on the local distribution of salamanders are age-class competition and predation.