Jeffrey W. Stringer

Multi-camera surveillance systems for time and motion studies of timber harvesting equipment

A multi-camera security system was tested to conduct a time and motion study.The system was installed on a John Deere 540G cable skidder.Time stamped video footage was inspected to obtain time consumption of work tasks.Accurate calculation of total cycle times and delays as well as productivity metrics.The system can be adopted as a reliable approach to conduct time and motion studies. We evaluated the feasibility of using a multi-camera security system to conduct time and motion studies. It was installed on a John Deere 540G cable skidder and connected to the skidders battery for continuous recording with minimal effort and intervention. After recording the skidders work for eleven experimental skidding cycles, time stamped video footage was visually inspected to obtain time consumption of work tasks, which provided for accurate calculation of total cycle times and delays. Several advantages of the security camera system including quick and non-invasive installation, large memory storage, transferability, resistance to weather elements, and the capacity to capture different views, offer a great potential for this method to be adopted as a reliable approach to accurately conduct time and motion studies. Along with distance and gradient information for skid-trail segments, we also explored the influence of gradient on travel time for loaded and unloaded skidding. There is a need for future studies to formally explore this relationship and develop more detailed cycle time equations that explicitly take into account skid-trail gradient for individual segments.

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.