Epigaea repens in Indiana : habitat associations and the effects of controlled burning

Abstract

As Epigaea repens L. (trailing arbutus) is a rare plant in Indiana, I studied four sites in south-central Indiana to identify habitat requirements and to locate additional sites. Habitat factors studied included soil type, companion vegetation, litter exposure, slope, 0 horizon depth, aspect, canopy cover, and pH. Epigaea repens is mostly found with litter exposure between 30-60%, slopes of 20-30°, O horizon 1.5-2.0 cm deep, an aspect between 180 " (south) and 330" (northwest), canopy cover > 70 %, low sapling density (0 to 0.12 saplings/rd), and a mean soil pH of 3.5. A controlled burn of 15 test plots was done to determine response to fire and litter removal. Flowering 13.5 months after the burn indicated that the burn had a significant negative effect. Seventeen and 1/2 months after the burn, a census of leaves, buds and stems indicated that the burn portions of the plots fared worse than the buffer or control portions. Twenty-five and 1/2 months after the burn the mean number of blossoms was still lower on the burn portions but it was not statistically significant. Sex ratios from three populations were measured for an indication of colony isolation and environmental conditions. All of the populations were slightly female biased. Competition with Vaccinium pallidum, a common companion species, may help restrict E. repens. Sites without E. repens but where the pH is suitable and where Vaccinium pallidum occurs were examined to help determine whether the distribution of E. repens is caused by historic accident or local habitat factors. The future outlook for the persistence of E. repens is positive. Suggestions for a management plan are (1) to locate additional sites, (2) to avoid timber harvesting near present sites in Morgan-Monroe State Forest and (3) to avoid burning as a management tool.