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 (WEPP-Roads), 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.

Sediment is the leading nonpoint source pollutant from forest operations in the United States. Sediment in forested watersheds is produced primarily from highly disturbed areas, such as skid trails. Forestry best management practices (BMPs) have been developed to minimize erosion and water quality problems, but the efficacies of various BMP options are not well documented. This study evaluated five bladed skid trail closure BMPs for erosion control in the Piedmont of Virginia. The BMP closures evaluated were (1) water bar only; (2) water bar and grass seed (grass); (3) water bar, grass seed, and straw mulch (mulch); (4) water bar and piled hardwood slash (H-slash); and (5) water bar and piled pine slash (P-slash). The study was arranged as a randomized complete block design where six newly constructed trails provided six blocks. Five treatments were applied to five segments within each block. Erosion from the 30 treatment plots (experimental units) was captured in sediment traps and weighed monthly for 13 months, providing 78 erosion weights per treatment. Results indicate that water bar was the most erosive closure method (137.7 t [metric tons] ha⁻¹ year⁻¹), followed by grass (31.5 t ha⁻¹ year⁻¹), H-slash (8.9 t ha⁻¹ year⁻¹), P-slash (5.9 t ha⁻¹ year⁻¹), and mulch (3.0 t ha⁻¹ year⁻¹). Overall, BMPs that provide soil coverage levels similar to either slash or mulch closure should provide good erosion control, and final selection should be based on costs, availability of material, or landowner objectives.

Forestry best management practices (BMPs) were developed to minimize water pollution from forestry operations by primarily addressing sediment and sediment transport, which is the leading source of pollution from silviculture. Implementation of water quality BMPs may also benefit riparian and aquatic wildlife, although wildlife benefits were not driving forces for BMP development. Therefore, we reviewed literature regarding potential contributions of sediment-reducing BMPs to conservation of riparian and aquatic wildlife, while realizing that BMPs also minimize thermal, nutrient, and chemical pollution. We reached five important conclusions: (1) a significant body of research confirms that forestry BMPs contribute to the protection of water quality and riparian forest structure; (2) data-specific relationships between forestry BMPs and reviewed species are limited; (3) forestry BMPs for forest road construction and maintenance, skid trails, stream crossings, and streamside management zones (SMZs) are important particularly for protection of water quality and aquatic species; (4) stream crossings should be carefully selected and installed to minimize sediment inputs and stream channel alterations; and (5) SMZs promote retention of older-age riparian habitat with benefits extending from water bodies to surrounding uplands. Overall, BMPs developed for protection of water quality should benefit a variety of riparian and aquatic species that are sensitive to changes in water quality or forest structure.

Water quality indices were examined for paired upstream and downstream samples for 23 operational stream crossings and approaches during four periods. Stream crossings were (1) portable bridges (BRIDGE), (2) culverts backfilled with poles (POLE), (3) culverts with earth backfill (CULVERT), and (4) reinforced fords (FORD). The four operational periods were (1) prior to crossing installation (INITIAL), (2) after installation (INSTALL), (3) during harvest (HARVEST), and (4) after road closure (CLOSURE). Differences (Δ) in water samples collected above and below stream crossings were analyzed for Δtotal dissolved solids (ΔTDS), ΔpH, Δconductivity, Δtemperature, and Δsediment concentration. Data were analyzed as a completely randomized design with unequal replication (four to seven replications). Significant differences were observed (α < 0.10) among crossing types for Δtemperature, ΔTDS, ΔpH, and Δconductivity. Overall, the least disruptive crossing type for water quality was BRIDGE, but road standards and approach characteristics were also important. Modeled estimates of erosion demonstrated that CULVERT approaches had higher potential erosion than other crossings. Water quality parameters were most negatively affected during INSTALL and HARVEST and were apparently improving during CLOSURE. Permanent crossings were associated with significantly greater temperatures than temporary crossings, likely because of increased width of streamside management zone removal. Water quality effects could be minimized by installing appropriate best management practices during all harvest periods rather than waiting until CLOSURE. Findings should be used cautiously because individual site factors such as climate, site, soil, and operational variability will alter effects.