Effects of gap-based silviculture on thermal biology of a terrestrial reptile

Abstract

Context Terrestrial reptiles require varied thermal environments to promote optimal physiological performance, growth, reproduction, and survival. Aims Our study was designed to determine whether gap-based silvicultural practices offer suitable thermal environments for eastern box turtles (Terrapene carolina) by examining environmental temperature variation and body temperature of eastern box turtles in, and adjacent to, canopy gaps. Methods We recorded box turtle body temperature from 20 radio-tracked turtles and environmental temperatures (canopy gaps and undisturbed habitat) using temperature loggers from June to September 2014 in a managed forest after canopy gaps (0.28–1.13 ha gap–1) were created via gap-based silviculture. Key results Over the four-month study period, gap temperatures were generally higher than adjacent undisturbed microhabitats. Box turtle body temperatures were closely correlated with environmental temperatures in undisturbed habitat in June and July. Turtle body temperatures were, however, closely correlated with environmental temperatures in canopy gaps in August and September. In addition, box turtles in our study had activity areas that overlapped canopy gaps from 0 to 65%, depending on the individual. As percentage overlap of canopy gaps increased, turtle body temperatures were increasingly correlated with canopy gap temperatures. Furthermore, as percentage overlap of canopy gaps increased, daily mean body temperature records consistently stayed within the preferred box turtle body temperature range (20.2–26.2°C). Conclusions Our study suggests that gap-based silviculture can create thermally compatible environments for box turtles depending on the time of day and year, and that box turtles use these microhabitats to thermoregulate. Implications The application of relatively small-scale silvicultural practices (≤1 ha gap–1) that provide heterogeneity in forest structure, composition, and function may be a useful alternative to clearcutting and other intensive harvesting methods that are associated with declines in terrestrial reptile populations.