Geofences are virtual boundaries based on geographic coordinates. When combined with global position system (GPS), or more generally global navigation satellite system (GNSS) transmitters, geofences provide a powerful tool for monitoring the location and movements of objects of interest through proximity alarms. However, the accuracy of geofence alarms in GNSS-radio frequency (GNSS-RF) transmitter receiver systems has not been tested. To achieve these goals, a cart with a GNSS-RF locator was run on a straight path in a balanced factorial experiment with three levels of cart speed, three angles of geofence intersection, three receiver distances from the track, and three replicates. Locator speed, receiver distance and geofence intersection angle all affected geofence alarm accuracy in an analysis of variance (p = 0.013, p = 2.58 × 10−8, and p = 0.0006, respectively), as did all treatment interactions (p < 0.0001). Slower locator speed, acute geofence intersection angle, and closest receiver distance were associated with reduced accuracy of geofence alerts.

Abstract:Restoration of pine forests has become a priority for managers who are beginning to embrace ideas of highly heterogeneous forest structures that potentially encourages high levels of regeneration. This study utilizes stem-mapped stands to assess how simulated regeneration timing and magnitude influence longevity of reduced fire behavior by linking growth and yield model outputs to a crown fire prediction model. Treatment longevity was assessed as return time to within 10% of pre-treatment predicted wind speeds for the onset of passive (Torching) and active (Crowning) crown fire behavior. Treatment longevity in terms of Torching and Crowning was reduced 5 years for every 550 and 150 seedlings ha´1, respectively. Introducing regeneration as a single pulse further reduced Torching treatment longevity 10 years compared to other regeneration distributions. Crowning treatment longevity increased at higher site indices, where a 6 m increase in site index increased longevity 4.5 year. This result was contrary to expectations that canopy openings after treatments would close faster on higher productivity sites. Additionally, Torching longevity was influenced by the rate of crown recession, were reducing the recession rate decreased longevity in areas with higher site indices. These dependencies highlight a need for research exploring stand development in heterogeneous sites.

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Characterizing the moisture loss from felled trees is essential for determining weight-to-volume (W-V) relationships in softwood sawlogs. Several factors affect moisture loss, but research to quantify the effects of bole size and harvest method is limited. This study was designed to test whether bole size, harvest method, environmental factors, and the associated changes in stem moisture content of felled Douglas-fir (Pseudotsuga menziesii var. glauca Franco) affected the weight-to-volume relationship of sawlogs. Thirty trees in three size classes (12.7-25.4 cm, 25.5-38.1 cm, 38.2-50.8 cm) were felled and treated with one of two harvesting processing methods. Moisture content was sampled every two days for four weeks. Results showed 6% greater moisture loss in the crowns of stems that retained limbs after felling compared to stems with limbs removed after harvesting. Additionally, moisture loss rate increased as stem size decreased. The smallest size class lost 58% moisture content compared to 34% in the largest size class throughout the study duration. These stem moisture content changes showed a 17% reduction in average sawlog weight within the largest size class, shifting current W-V relationships from 2.33 tons m −3 to 1.94 tons m −3 during the third seasonal quarter for northern Idaho Douglas-fir and potentially altering relationships year-round. OPEN ACCESSForests 2014, 5 2290

As weight-based timber sales become more common in the Intermountain West, characterizing the factors affecting weight-to-volume relationships for softwood sawlogs has become more important. Several factors are thought to affect sawlog weight and volume (W:V) relationships, but the relative importance of weather, topography, species, and region in the western United States has not been quantified. Analysis was conducted to determine the factors affecting W:V relationships across the state of Idaho for commercial softwood sawlogs. Using 7,929 sorted and scaled sawlog loads sampled throughout Idaho from 2011 to 2013, we studied the relationships between log small-end diameter (SED), region, atmospheric temperature, precipitation, and elevation, to assess changes in W:V. Relationships of W:V using mixed-effects models were strong (R2 of 0.74 to 0.90, P < 0.05) when fitted individually by species, with volume modeled as a function of weight, SED, truckload piece count, percent defect, and seasonal quarter: Y (board foot volume) = β0 + β1 (Tons) + β2 (SED) + β3 (Piece Count) + β4 (Length) + β5 (Defect) + β6 (Seasonal Quarter) + β7 (1|Sale Number/Ticket) + u (Error).