W. Michael Aust

Soil quality assessment in domesticated forests – a southern pine example

Maintenance and enhancement of soil productivity is central to the long-term success of intensive forest management. A simple technique is required for monitoring the effects of different management practices on soils as an aid in developing codes of practice that foster maintenance and enhancement of soil productivity. The objective of our work was to determine if management impacts on soil productivity could be assessed using the soil-quality concepts developed in agriculture. A soil-quality index (SQI) model, that measures the effects of management practices on five key growth-determining attributes of forest soils, namely (1) promote root growth, (2) store, supply and cycle nutrients, (3) accept, hold, and supply water, (4) promote gas exchange, and (5) promote biological activity, was developed and tested as part of a controlled study in intensively-managed pine plantations on the Lower Coastal Plain of South Carolina. Three 20-ha, 20-year-old loblolly pine plantations were harvested under wet and dry conditions to create a broad gradient in soil disturbance. Within each harvested plantation, a subset of 3-ha plots were site prepared by either bedding or mole-plowing plus bedding, then all sites were established as third-rotation pine plantations. Field data were collected spatially for soil bulk density, net N mineralization, water table depth, soil aeration, and soil moisture. Literature-based sufficiency values were determined for each property and substituted into the SQI model as surrogate indicators for the five key attributes, thus obtaining spatial SQI predictions within each harvesting and site preparation treatment. Our study results demonstrate how SQI monitoring could be used to identify the effects of management practices on soil productivity, which should aid in developing codes of practice as a component of achieving long-term sustainability in domesticated forests.

Spatial and temporal patterns of carbon storage and species richness in three South Carolina coastal plain riparian forests.

Abstract The distribution of organic matter within a floodplain is a controlling factor affecting water quality, habitat, and food webs. Accordingly, development of vegetation in the riparian zone can be expected to influence ecosystem functions, and organic matter storage patterns are believed to be indicators of functional recovery in disturbed riparian zones. Our objective was to compare the distribution and allocation of organic matter among microsites within the floodplain and with temporal changes (successional status) associated with community development. Three third order streams in the upper coastal plain of South Carolina were selected. Measurement transects were established across three floodplains of varying successional status, Meyers branch; a mature riparian hardwood forest; Fourmile branch; a mid-successional riparian forest; and Pen Branch, an early successional riparian forest. Overall, measurements of aboveground biomass, soil carbon, and stand structure indicate that the early and mid successional stands are becoming more similar to the mature stand and that microsite differences within the braided, riparian stream systems are small.

Recovery status of a tupelo-cypress wetland seven years after disturbance: silvicultural implications

Abstract Three disturbance treatments were imposed on a palustrine forested wetland ( Nyssa aquatica-Taxodium distichum ) located in southwestern Alabama in 1986: (i) clearcutting with helicopter log removal (HELI), (ii) HELI followed by rubber-tired skidder traffic simulation (SKID) and (iii) HELI followed by removal of all vegetation during the first two growing seasons via glyphosate herbicide application (GLYPH). After two growing seasons, it was hypothesized that eventual woody plant growth would be best in the HELI-treated areas, because SKID plots had reduced rates of water movement and soil aeration. However, measurements at stand age seven years indicate that SKID actually has greater total above-ground biomass (65979 kg/ha) than HELI (46748 kg/ha) and SKID plots have a higher proportion of the most desirable timber species ( Nyssa aquatica ). GLYPH areas resemble freshwater marshes, although the areas are being invaded by Salix nigra seedlings. All disturbance treatments have significant groundflora components that have increased sediment accumulation 70–175% relative to an undisturbed reference area. By age seven years, regrowth of vegetation has lowered the water table during the growing season but has had little effect on soil redox potential and pH. Our observations suggest that this wetland system is rapidly recovering from logging disturbance seven years ago.

Comparative effects of aerial and ground logging on soil properties in a tupelo-cypress wetland

Abstract A palustrine water tupelo ( Nyssa aquatica L.)-baldcypress ( Taxodium distichum (L.) Rich.) swamp in southwestern Alabama was subjected to three types of disturbances during the fall of 1986. Disturbance treatments were those associated with clearcutting of timber: log removal by helicopter, simulated rubber-tired skidder log transport, and herbicide control of vegetative regrowth. An adjacent undisturbed stand served as a reference. Post-harvest measurements of soil physical and chemical properties were collected in 1987 and 1988. Results indicated that saturated hydraulic conductivity is the dominant influence on soil functions within this ecosystem. Skidder trafficking significantly reduced saturated hydraulic conductivity within 50 cm of the soil surface, thereby decreasing water percolation and drainage on trafficked areas. The reduction of saturated hydraulic conductivity resulted in chemical reduction, decreased oxygen content and increased pH values in the soil of trafficked areas.

Effects of rhizosphere inundation on the growth and physiology of wet and dry-site Acer rubrum (red maple) populations

-Six-wk-old Acer rubrum L. (red maple) seedlings, grown from fruits collected on paired wet and dry sites on the Coastal Plain, Piedmont, and Ridge and Valley physiographic regions of Virginia, were flooded to determine whether there are ecotypic differences in growth and physiology between seedlings from wet and dry sites. Periodic harvests were conducted over 3 mo to measure growth of flooded and unflooded seedlings derived from three trees per site. Shoot water potential and gas exchange were measured for 2 wk to determine if the physiology of seedlings from wet and dry sites were affected differently by flooding. Flooding adversely affected seedling growth and physiology resulting in shorter (18%) and lighter (30% less leaf mass, 14% less stem mass and 68% less root mass) seedlings that had higher water potentials (20%) and reduced photosynthetic rates (50%). Significant differences developed between seedlings from wet and dry sites with the wet site seedlings having lower water potentials and taller, heavier shoots. However, no significant interactions between flooding and maternal hydrologic conditions were found that would indicate genetic differences in flood response between wet and dry site seedlings. This lack of a differential growth or physiological response to waterlogging by the distinct populations strongly suggests that young Acer rubrum seedlings do not exhibit ecotypic differences in flood tolerance.

Best management practices for forested wetlands in the Southern Appalachian Region

Forestry best management practices (BMPs) have been developed for all of the states included in the Southern Appalachian Region (Alabama, Georgia, Kentucky, North Carolina, South Carolina, Tennessee, Virginia, West Virginia). All of the state forestry BMPs were developed to reduce nonpoint source pollution from forestry operations. However, the states have developed BMPs that differ substantially with regard to methodology, particularly for forested wetlands. The state BMP guidelines vary in several major areas, including wetland types, BMP manual detail, streamside management zones, harvesting operations, site preparation operations, regeneration systems, road construction, and timber removal activities. An understanding of the similarities and differences between the state BMP guidelines will allow the forested wetland manager to comply with or improve upon existing forestry BMPs for wetlands.

Recreational Stream Crossing Effects on Sediment Delivery and Macroinvertebrates in Southwestern Virginia, USA

AbstractTrail-based recreation has increased over recent decades, raising the environmental management issue of soil erosion that originates from unsurfaced, recreational trail systems. Trail-based soil erosion that occurs near stream crossings represents a non-point source of pollution to streams. We modeled soil erosion rates along multiple-use (hiking, mountain biking, and horseback riding) recreational trails that approach culvert and ford stream crossings as potential sources of sediment input and evaluated whether recreational stream crossings were impacting water quality based on downstream changes in macroinvertebrate-based indices within the Poverty Creek Trail System of the George Washington and Jefferson National Forest in southwestern Virginia, USA. We found modeled soil erosion rates for non-motorized recreational approaches that were lower than published estimates for an off-road vehicle approach, bare horse trails, and bare forest operational skid trail and road approaches, but were 13 times greater than estimated rates for undisturbed forests and 2.4 times greater than a 2-year old clearcut in this region. Estimated soil erosion rates were similar to rates for skid trails and horse trails where best management practices (BMPs) had been implemented. Downstream changes in macroinvertebrate-based indices indicated water quality was lower downstream from crossings than in upstream reference reaches. Our modeled soil erosion rates illustrate recreational stream crossing approaches have the potential to deliver sediment into adjacent streams, particularly where BMPs are not being implemented or where approaches are not properly managed, and as a result can negatively impact water quality below stream crossings.

Characteristics of Logging Businesses that Harvest Biomass for Energy Production

Abstract Utilization of biomass from logging residues for renewable energy production depends on forest harvesting businesses. As biomass markets emerge, businesses will need to adapt to meet opera...

Best Management Practices for Low-Volume Forest Roads in the Piedmont Region: Summary and Implications of Research

Forest roads provide important access for forest management activities, yet those roads, skid trails, and stream crossings have repeatedly been reported as major sources of sediment. The passage of the Federal Water Pollution Control Act of 1972 focused considerable research on the development of forestry best management practices (BMPs) for reducing sediment input from forest roads. Recent litigation in the U.S. Supreme Court has reemphasized the importance of enhancing BMPs for forest roads. This paper synthesizes and interprets two decades of applied research on BMPs for low-volume forest roads, with emphasis on research conducted on forest operations in the Virginia Piedmont region. BMP interpretations include (a) current BMP status for forest roads, skid trails, and stream crossings; (b) advantages of preharvest planning; (c) forest road design; (d) forest road closure; (e) recommended BMPs for legacy roads; (f) guidelines for minimizing area of forest roads; (g) deck and skid trail rehabilitation; (h) closure of bladed and overland skid trails; (i) alternative harvest systems; (j) permanent and temporary closure of the stream crossing; (k) selection of stream crossing types; and (l) recommendations for streamside management zones. Major conclusions from this synthesis are that forest roads, skid trails, and stream crossings continue to be ranked as problem sources of sediment, but forestry BMPs can be used to reduce sediment inputs from such areas. Problems with road and skid trails can generally be attributed to poor planning and insufficient quantity or quality of BMPs.

Evaluation of Bladed Skid Trail Closure Methods in the Ridge and Valley Region

Forest roads and skid trails with inadequate best management practices (BMPs) often contribute the majority of erosion produced from forest harvesting operations. We evaluated soil erosion rates from bladed skid trails in the mountains of Virginia after a timber harvest. The randomized complete block design included six blocks, each containing four skid trail closure BMP treatments (waterbar only [Control], slash-covered [Slash], seeded [Seed], and seeded with fertilizer and mulch [Mulch]). Control treatments resulted in an average erosion rate of 6.8 tons ac 1 yr 1 (15.1 tonnes ha 1 yr ) following installation. Seed treatments resulted in an average erosion rate of 2.6 tons ac 1 yr 1 (5.9 tonnes ha 1 yr ). Mulch treatments averaged 0.5 ton ac 1 yr 1 (1.1 tonnes ha 1 yr ), and Slash treatments averaged 0.4 ton ac 1 yr 1 (0.8 tonnes ha 1 yr ). Seed, Mulch, and Slash treatments significantly reduced soil erosion rates in comparison to Control treatments (P 0.0315), with Mulch and Slash treatments being most effective (P 0.0001). Results indicate that ground cover treatments are beneficial in addition to waterbars for effective erosion control. A cost analysis indicates that Seed treatments are the most cost-effective (