Effectiveness and implementation costs of overland skid trail closure techniques in the Virginia Piedmont

Abstract

Soil erosion is influenced by factors such as soil properties, slope, ground cover, climatic conditions, and forest management activities, including skid trails. Skid trails typically represent 2% to 10% of a timber harvest's area; therefore, the potential to negatively affect site productivity and water quality as a result of harvesting is of concern. Soil erosion can reduce site nutrient reserves and increase sedimentation of nearby streams. Forestry best management practices (BMPs) are designed to provide effective techniques for maintaining environmental stability. Although BMPs are widely implemented, few data exist regarding the efficacy and costs of different BMP options for skid trail closure. The study objectives were to evaluate erosion control effectiveness and implementation costs of five overland skid trail closure techniques. The closure techniques were (1) waterbar only (Control), (2) waterbar plus seed (Seed), (3) waterbar plus seed and mulch (Mulch), (4) waterbar plus hardwood slash (Hardwood), and (5) waterbar plus pine slash (Pine). Each treatment was installed following harvesting and replicated on four trails to provide twenty experimental erosion plots. Geotextile sediment traps (Dirtbags) were used to filter skid trail sediment. Accumulated sediments were weighed monthly for one year, and erosion rates were determined for each treatment. Two commonly used erosion models, Universal Soil Loss Equation as modified for forests (USLE-Forest) and Water Erosion Prediction Project for Forest Roads (WEPPRoads), were also applied to each treatment. Sediment collected from traps indicated that the Mulch treatment was the most effective for reducing erosion (3.29 Mg ha -1 y -1 [1.47 tn ac -1 yr -1 ]), followed by Hardwood (5.08 Mg ha -1 y -1 [2.27 tn ac -1 yr -1 ]), Pine (5.40 Mg ha -1 y -1 [2.41 tn ac -1 yr -1 ]), Seed (13.57 Mg ha -1 y -1 [6.06 tn ac -1 yr -1 ]), and Control (24.24 Mg ha -1 y -1 [10.82 tn ac -1 yr -1 ]). Overall, WEPP-Roads estimates were more similar to measured erosion than USLE-Forest estimates, but both models generally agreed with actual erosion trends. The Seed treatment was the least expensive beyond waterbars alone, but it was only moderately effective at limiting erosion. Incorporating slash dispersal and compaction onto overland skid trails during harvesting activities may be the best option for reducing BMP costs and long term soil stability on disturbed soils associated with log skidding.

Differing Levels of Forestry Best Management Practices at Stream Crossing Structures Affect Sediment Delivery and Installation Costs

“…Reduction of in-stream sediment with increased BMPs is similar to findings of other studies for skid trail erosion [24,31] and haul road stream crossing approaches [33,34]. The BMP+ treatment in this study was designed to minimize bare soil and to armor as much disturbed soil as practically possible.…”

“…Such erosion control BMPs are epitomized by the retention of soil litter layers, re-establishment of vegetation, and application of soil cover such as mulch or slash [28]. Erosion control measures, including straw mulch, slash [24,[29][30][31], and gravel [3,[32][33][34] have been found to reduce erosion potential. Edwards and Williard [35] evaluated three studies of BMP efficiency for sediment reduction and found that the efficiency of BMPs as well as total sediment loads decreased as time after harvest increased.…”

Estimating Costs and Effectiveness of Upgrades in Forestry Best Management Practices for Stream Crossings

“…Wade et al [57] and Sawyers et al [58] conducted companion studies that evaluated BMPs for closing bladed and overland skid trails in the Piedmont region. Both studies found that slash and mulch with seed were highly effective treatments for skid trail closure and erosion control.…”

“…Christopher and Visser [73] advocated use of the USLE-Forest methodology for evaluating the adequacy of forestry BMPs, and several researchers have found that the model compares favorably with direct measures of soil erosion for both roads [16,74] and skid trails [58,75] in the Piedmont region. Egan [76] emphasized that the USLE-Forest is particularly useful for evaluating road and stream crossing BMPs because data collection for model parameterization focuses the reviewer on site attributes that are often addressed by forestry BMPs.…”

Estimating Soil Displacement from Timber Extraction Trails in Steep Terrain: Application of an Unmanned Aircraft for 3D Modelling

“…In steeper terrain a bulldozer or skidder with dozer blade is used in providing temporary access to machines, resulting in more drastic changes to the terrain. This practice and its associated problems, has been documented in western [1] and eastern USA [2][3][4][5], in Japan [6], Malaysia [7,8] and Australia [9][10][11].…”