Bladed skid trails are a common operational feature of timber harvesting in mountainous Appalachian terrain that can persist for decades, but their impact on long-term site productivity is not fully understood. The region's steep slopes and karst geology present challenging recovery conditions that make it particularly susceptible to lasting soil disturbance which may affect forest regeneration and timber yield. This study quantifies the long-term effects of bladed skid trails on forest productivity by comparing tree volume growth across four distinct site condition treatments: undisturbed areas, margins above and below bladed skid trails, and on the bladed skid trails themselves. Each treatment is represented by a subplot, with the four subplots together comprising one plot. This information is then coupled with an estimate of the percentage of area bladed skid trails occupy to determine site-wide productivity differences. The study examines 75 plots across 17 distinct sites harvested on average 78 years ago near Greenbrier and Nicholas counties, West Virginia. Sites had an average slope of 37%, elevation of 3,114 feet above sea level, and were composed of mixed hardwoods with common species sugar maple, northern red oak, and black cherry. All sites were clearcut with ground-based mechanized systems utilizing bladed skid trails for felled tree extraction. Mean volume per acre showed major differences on bladed skid trails (219 ft3/acre) compared to the undisturbed control area (4247 ft3/acre). Margin treatments showed substantial increases in volume per acre compared to the control with averages of 6376 ft3/acre for margins below and 5685 ft3/acre for margins above. Comparing site productivity effects, accounting for marginal area gains, and on trail losses led to an overall site decrease of 1.1% volume per acre (95% CI: -6.3% to +4.1%). Estimated value at the site level showed an overall increase of 3.5% (95% CI: -3.8% to +10.8%) that was driven by increased sawtimber. This study provides evidence that the margins beside a bladed skid trail may partially or fully compensate for the losses within the bladed skid trail, indicating their presence may not be detrimental to overall growth and value recovery.

Logging on steep mountain terrain in Appalachia often requires cutting flat paths, called bladed skid trails, into hillsides so that heavy machinery can drag (skid) harvested trees to a central loading area (landing). Construction of these trails bulldozes away the topsoil and reshapes the ground, and the damage can last for decades. While previous research has shown that trees struggle to grow directly in the paths of bladed skid trails, there is a lack of research on what happens to the forest immediately beside them. This study measured tree growth and estimated timber value at 17 sites that were all previously clearcut (entirely cut down) between 65 and 97 years ago, which is old enough to be harvested again. Sites were located near Greenbrier and Nicholas counties, WV, and had steep slopes averaging 37%, mixed hardwood species, and an average elevation of 3114 feet. At each site four zones were compared, on the path of the bladed skid trail, directly below it, directly above it, and an unaffected baseline zone (control) even further above. Trees growing on the old, bladed skid trail produced almost no usable wood, 95% less volume per acre than the undisturbed control. However, the trees in the zones directly adjacent to the bladed skid trail showed the opposite effect. The zone directly below the bladed skid trail produced 47% more volume, and the zone directly above produced 33% more volume. These increases likely resulted from reduced competition for sunlight, water, and growing space. The next objective of this study is whether these marginal gains adjacent to the bladed skid trail are enough to offset the losses within them. With each of the different zones at the proportion of the total harvest site that they occupy, there was an overall site effect of -1.1% volume per acre versus a hypothetical calculation of the site where there are not any bladed skid trails. For value, there was a 3.5% increase overall. These findings suggest that bladed skid trails may not incur productivity losses like previously assumed, when incorporating the growth increases to areas beside bladed skid trails.

Master of Science