W.M. Aust

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

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 harvests 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.

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

Forestry Best Management Practices (BMPs) are used for protection of water quality at forest stream crossings, yet effects and costs for gradients of BMPs are not well documented. We evaluated forty-two truck road and skid trail stream crossings using three surrogates of BMP adequacy: (1) potential erosion rates for stream crossing approaches; (2) adequacy of stream crossing BMPs; and (3) overall BMP rating (BMP−, BMP-standard, and BMP+). Subsequently, BMP upgrades were recommended for enhancing BMP− or BMP-standard stream crossings. Costs for BMP upgrades were estimated using an existing road and skid trail cost method. The majority of truck road stream crossings were culverts, while skid trail stream crossings were primarily portable bridges. Potential erosion estimates, BMP audit scores, and BMP ratings all indicated that skid crossings have lower BMP implementation than truck road crossings. BMP improvements commonly identified for skid trail and truck crossings included addition of cover and water control structures. Improved BMPs at skid trail crossings were less expensive than those at truck road crossings. Current BMP guidelines provide economical and effective techniques for reducing erosion, and BMP upgrades have the potential to reduce erosion rates to similar levels found in undisturbed forests.

Soil Physical Property Changes After Skidder Traffic With Varying Tire Widths

Eight combinations of skidder tires, ranging in total width from 0.7 m to 2.2 m, were evaluated for rut formation potential on two soils in south-central Alabama. One was a mixed pine-hardwood bottomland; the other was an upland, predominantly pine stand. Each soil/tire combination was replicated twice. Changes in soil profile after one, three, seven, and nine loaded passes were used as indices of soil disturbance. The number of skidder passes was the most significant factor influencing rut formation. The effect was linear up to nine passes on both test sites. The first pass on the upland site accounted for half the average rut depth and area. The magnitude of the displacement after one pass was related to tire width. Each subsequent pass caused a uniform smaller increment in depth and area. The magnitude of the increase was independent of tire width. On the bottomland site, however, each pass resulted in an increment in both depth and area the magnitude of which was a function of tire width. Average rut cross-sectional area on the bottomland site ranged from 0.13 m2 to 0.75 m2 for nine passes. Depth of ruts ranged from 1.7 cm to 3.6 cm for nine passes on the upland soil, and from 1.4 cm to 21.2 cm for nine passes on the bottomland soils. Soil physical properties were not affected by skidder traffic regardless of tire width.

The influence of elevated carbon dioxide and water availability on herbaceous weed development and growth of transplanted loblolly pine (Pinus taeda)

Loblolly pine (Pinus taeda L.) seedlings were grown in competition with native weeds using soil and seed bank collected from recently chopped and burned areas near Appomattox, Virginia. One-year-old seedlings were planted and weeds allowed to germinate from the native seed bank while being exposed to CO(2) (ambient and elevated - approximately 700 ppm) and water (water stressed and well watered) treatments for approximately one growing season in a greenhouse. Elevated CO(2) did not influence total weed biomass; however, C(3) weed community development was favored over C(4) weed community development in elevated CO(2) regardless of water availability. This suggests that weed community composition may shift toward C(3) plants in a future elevated CO(2) atmosphere. Pine growth was significantly greater in the well watered and elevated CO(2) treatments compared to the water stressed and ambient treatments, respectively, even though they were competing with native herbaceous weeds for resources. There was a significant water and CO(2) interaction for pine root:shoot ratio. Under elevated CO(2), root:shoot ratio was significantly greater in the water stressed treatment than the well watered treatment. In contrast, there was no significant difference in the root:shoot ratio under the ambient CO(2) treatment for either water treatment. These results suggest that loblolly pine seedlings will respond favorably in an elevated CO(2) atmosphere, even under dry conditions and competing with herbaceous weeds.

Drainage effects on plant diversity and productivity in loblolly pine (Pinus taeda L.) plantations on wet flats

Abstract Silvicultural practices are under increased scrutiny with respect to environmental impacts and intensive forestry is often cited as a contributing factor in the decline of biodiversity. However, there are few studies which evaluate the long-term impact of forest operations on plant diversity and production. The objective of this project was to determine the rotation age effects of three site preparation methods on plant diversity and productivity in wet pine flat plantations. The study are consisted of three wetland sites in the coastal plain of Virginia. Treatments were originally established in 1969 to study the effects of site preparation on loblolly pine ( Pinus taeda ) growth. The three site preparation treatments applied were: chop and burn, bedding between windrows (windrow-bedding), and secondary ditching. This study was conducted in 1991 when stands were near rotation age (22 years). Plant diversity was lowest and total biomass highest on the windrow-bedding treatment. Windrow-bedding appeared to increase pine growth by providing seedlings with more available soil volume and by reducing the vegetative regeneration of hardwoods and shrubs, thereby decreasing diversity. Secondary ditching increased pine growth by lowering water table levels, but had little effect on plant diversity.

Potential adoption of agroforestry riparian buffers based on landowner and streamside characteristics

Riparian forest buffers provide numerous environmental benefits, yet obstacles to landowner adoption are many. One barrier is the perception that riparian forest buffers are used for conservation at the expense of production. We present a study that focused on why landowners are more or less inclined to adopt native fruit and nut tree agroforestry riparian buffers that achieve both. We surveyed owners of nonforested streamsides in three Virginia watersheds and grouped survey respondents into three segments: (1) stream-source livestock producers, (2) alternative-source livestock producers, and (3) nonproducers. We also measured the importance owners place on management outcomes, their beliefs about riparian forest buffer effectiveness, and their reaction to potential benefits associated with using native fruit and nut tree agroforestry systems. We then tested whether these variables differ among streamside owner segments. Differences were observed in importance of land use outcomes, riparian buffer beliefs, and responses to potential benefits of native fruit and nut tree systems. A geographic information system was used to study streamside characteristics, which varied across owner segments in total potential planting space but differed more so in the total amount of erodible soil that could be conserved through the use of native fruit and nut tree buffers. Results suggest that conservation programs focused on native agroforestry systems would benefit by prioritizing and tailoring initiatives according to social and biophysical variables.

Forestry best management practices and modeled erosion on planned and logger-selected bladed skid trails in the Ridge and Valley region, Virginia, USA

ABSTRACT Forestry Best Management Practices (BMPs) are techniques and approaches recommended by state forestry agencies to protect water quality from forestry operations. Poorly designed roads and skid trails with inadequate BMPs can potentially generate disproportionately large quantities of sediment, which is the primary pollutant from forest operations. Bladed skid trails, which are constructed on steep terrain to allow skidder access, have greater potential to produce sediment than overland skid trails. BMP recommendations advise pre-harvest planning and layout of bladed skid trails in order to minimize erosion, yet equipment operators commonly construct bladed skid trails with minimal planning. We examined pre-harvest planned and logger-selected skid trails to characterize differences in BMP implementation and potential erosion between the two skid trail layout/construction strategies. A total of 25 and 27 sample locations on logger-selected and pre-harvest planned bladed skid trails were installed on two recent timber harvests on steep terrain in the Ridge and Valley region in Montgomery County, Virginia, USA. Both planned and logger-selected trails were on similar terrain and were constructed by the same logging crew. Assessments included skid trail slope, soil cover, water control structure implementation and spacing, trail network geometries, and predicted soil erosion. Analyses revealed that slopes, trail areas, and erosion rates were significantly lower on pre-harvest planned bladed skid trails. Overall, bladed skid trails with pre-harvest planning resulted in more effective water control BMPs and reduced potential for soil erosion than logger-selected trails. Results emphasize that pre-harvest planning of bladed skid trails is an appropriate BMP for steep terrain.

Forestry best management practices for erosion control in haul road ditches near stream crossings

Poorly designed and maintained forest road stream crossings can directly link erosion sources to streams. Forestry best management practices (BMPs) provide techniques that are useful for preventing sedimentation associated with ditch erosion. However, few studies have quantified ditch BMP sediment reductions. Thus, our primary objective was to evaluate erosion control effectiveness due to ditch BMPs and secondarily to quantify ditch BMP implementation costs. Sixty ditch segments near stream crossings were reconstructed, and five ditch BMP treatments were applied using a completely randomized design resulting in 11 to 13 replications per treatment. Ditch BMP treatments were (1) bare ditch (Bare), (2) grass seed with lime fertilizer (Seed), (3) grass seed with lime fertilizer and erosion control mat (Mat), (4) rock check dams (Dam), and (5) completely rocked (Rock). Silt fence sediment traps and sediment pins were measured over one year to determine treatment effectiveness. Trapped sediment deposits indicated that median erosion rates were greatest for Dam (6.14 Mg ha−1 y−1 [2.74 tn ac−1 yr−1]), followed by Bare (4.92 Mg ha−1 y−1 [2.19 tn ac−1 yr−1]), Rock (1.73 Mg ha−1 y−1 [0.77 tn ac−1 yr−1]), Seed (1.04 Mg ha−1 y−1 [0.46 tn ac−1 y−1]), and Mat (0.82 Mg ha−1 y−1 [0.37 tn ac−1 yr−1]). Results suggested that Mat treatments had significantly lower erosion rates than Bare and Dam, while Rock and Seed provided intermediate levels. Costs of BMP treatments were least expensive for Seed (US

Forest operations, extreme flooding events, and considerations for hydrologic modeling in the Appalachians—A review

6.10 approach−1), followed by Mat (US

Intensive Utilization of Harvest Residues in Southern Pine Plantations: Quantities Available and Implications for Nutrient Budgets and Sustainable Site Productivity

21.33 approach−1), Dam (US