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This paper summarizes the results of an update to a resource assessment, published in 2005, commonly referred to as the Billion-Ton Study (BTS). The updated results are consistent with the 2005 BTS in terms of overall magnitude. The 2005 BTS projected between 860 and 1240 Tg of biomass available in the 2050 timeframe, while the Billion-Ton Update (BT2), for a price of 66 $ Mg−1, projected between 994 and 1483 Tg in 2030. For the BT2, forest residue biomass potential was determined to be less owing to tighter restrictions on forest residue supply including restrictions due to limited projected increase in traditional harvest for pulpwood and sawlogs. Crop residue potential was also determined to be less because of the consideration of soil carbon and not allowing residue removal from conventionally tilled corn acres. Energy crop potential was estimated to be much greater largely because of land availability and modeling of competition among various competing uses of the land. Generally, the scenario assumptions in the updated assessment are much more plausible to show a “billion-ton” resource, which would be sufficient to displace 30% or more of the country's present petroleum consumption and provide more than enough biomass to meet the 2022 requirements of the Renewable Fuel Standard.

Nationwide, county-level supply curves have been estimated for forest-based biomass to evaluate their potential contributions to producing biofuels. This study builds on the estimates of potential supply in the Billion Ton Supply study prepared by the U.S. Department of Agriculture and the U.S. Department of Energy. Forest biomass sources include logging residue, thinnings, other removals, unused mill residue, urban wood waste, and conventionally sourced wood (pulpwood size material). To make the estimates, we assume that lower cost forest biomass will be supplied from integrated harvesting operations that also remove sawlogs and pulpwood. We also assume that such removals can be estimated at the county level in two ways: first, as a portion of recent estimates of logging residues; and second, by simulated thinning operations that use tops, branches, and small trees for biomass. Supply from thinning dense forest stands is assumed to occur over 30 yr. Harvest and stumpage costs are estimated for each of th...

Soil disturbance patterns and associated changes in soil physical status were measured in a study that evaluated the implementation of three alternative management prescriptions in an upland hardwood stand in northern Alabama, USA. Management prescriptions applied in this study consisted of a clear-cut, strip cut, and deferment cut that were compared to a non-harvested control. Final tabulations of disturbance types indicated disturbance to be similar in clear-cut and deferment cut treatments with less disturbance in strip cut sites. Soil physical response varied by soil property but, in general, as disturbance intensity increased, soil physical properties responded accordingly. Bulk densities were elevated to the highest degree in the clear-cut sites while soil strength as indicated by cone index measurements attained its highest levels in the deferment cut. These differences were thought to be due to differences in trafficking patterns related to the implementation of each management prescription.

The cutslope and fillslope on a newly constructed forest road on the Talladega National Forest near Heflin, Alabama were treated with three erosion control techniques: wood excelsior erosion mat, native grass species, and exotic grass species. Bare soil plots were used as the experimental controls. Total sediment yield was measured during the period 21 September 1995 to 18 March 1996. A randomized complete block design was used to evaluate treatment methods on the basis of sediment yield and runoff volume. No significant difference in sediment yield was found from the fillslope among the treatments. However, on the cutslope significant differences were detected among all treatments. The erosion mat treatment was most effective in mitigating erosion losses with a 98% reduction in cutslope sediment yield and 88% reduction in fillslope sediment yield.

Surface soil properties were compared among disturbance classes associated with a single-tree selection harvest study installed in 1979 in the Brazilian Amazon. Response variables included pH, total N, total organic C, extractable P, exchangeable K, Ca, Mg, and bulk density. In general, concentrations of all elements displayed residual effects 16 years after harvests with N, P, K, and C being inversely related to disturbance intensity while Ca and Mg levels as well as pH were directly related. Elemental contents exhibited fewer residual effects except in the cases of Ca and Mg contents which generally increased with disturbance intensity. Higher intensity disturbance classes were associated with increased bulk density. Soil impacts apparent after 16 years suggest a combination of direct effects of harvests (e.g. as in the case of bulk density) combined with indirect influences of the ecophysiology of the Cecropia sp. which dominate disturbed areas.

Floodplain forests contribute to the maintenance of water quality as a result of various biogeochemical transformations which occur within them. In particular, they can serve as sinks for nutrient run-off from adjacent uplands or as nutrient transformers as water moves downstream. However, little is known about the potential that land management activities may have for alteration of these biogeochemical functions. This paper examines the effects of three harvesting regimes (unharvested control, clearcut, and partial cut) on the physical and chemical parameters within the Flint River floodplain located in southwestern Georgia, USA. Data presented in this paper were collected during the year following initiation of the harvesting treatments which occurred in September of 1993. Sheetflow water chemistry (total suspended solids (TSS), total dissolved solids (TDS), nitrate (NO3−), phosphate (PO43−), sulfate (SO42−), calcium (Ca2+), potassium (K+), magnesium (Mg2+), ammonium (NH4+), total phosphorous (P), total nitrogen (N), total carbon (C), dissolved organic carbon (DOC)), sedimentation rates, depth of soil oxidation after flooding, saturated hydraulic conductivity, and bulk density were measured. During the year immediately after treatment installation, alterations in some of the physical and chemical properties (TDS, NO3−, total P, and K+) of floodwaters crossing harvest plots were detected. Soil oxidation depths, saturated hydraulic conductivity and bulk density also changed with treatment. The meaning of the changes detected is uncertain but they suggest the nature of potential changes in nutrient spiralling and non-point source cumulative effects that may occur within a managed watershed. Second-year data may offer an interesting comparison of sheetflow chemistry and sedimentation changes between vegetated and non-vegetated conditions.

Environmentally acceptable and economical forest operations are needed for sustainable management of forest resources. Improved methods for harvesting and transporting timber are especially needed for wet sites. As the demand for hardwood lumber continues to increase, improved and alternative methods are needed to ensure acceptance of timber harvesting for the wet site conditions that are typical of bottomland hardwoods. Some alternative technological developments include grapple saw feller-bunchers, wide tires, larger forwarders, clambunk skidders, two-stage hauling, mats, cable systems, helicopters and towed vehicles and air-cushioned vehicles. These developments have the potential to improve the performance of the harvesting system and to reduce the negative effects of conventional operations on conventional sites and on difficult sites such as wet areas. Although many of these new alternatives are now operational, others are just concepts or evolving prototypes. More research is still needed to optimize these alternative technologies and to reduce costs associated with their implementation.

Access systems are a necessary element of resource production in bottomland hardwood sites. However, road building may have a detrimental effect on hydrologic function of the site. This report describes initial results of a study designed to examine the effect of different road surfacing treatments on water quality. Four surfacing treatments installed on two test roads included native soil, native soil with vegetative stabilization, 6 cm of gravel, and 15 cm of gravel over geotextile. During the first flooding season periodic sampling measured floodwater suspended sediments and location of erosion and sediment deposition within the road prism. Initial results suggest that sediment movement was confined to the road right-of-way, with no statistically significant sedimentation effects detected beyond the clearing limits of the road. The study is continuing for another field season.

Secondary transportation from the forest to the utilisation facility is the simplest of the handling phases in transferring fuelwood from its point-of-origin to ultimate processing point, both in its objectives and application. In spite of this simplicity secondary transport is typically responsible for between 20 and 40% of the delivered fuel cost. Truck transportation is in an advanced state of development as the technology employed comes from a very large scale industry that dominates the transport of industrial products in most developed countries. To achieve a full payload within maximum allowable load dimension restrictions the material transported must have a minimum bulk density of about 250 to 280 kg/m 3 . While conventional forest products generally exceed this limit, fuelwood in an unprocessed form may have a bulk density of only 120 to 150 kg/m 3 . To offset this problem fuelwood material can be compacted before loading, or compacted in the trailer, but, more frequently, it is comminuted before transport. Processing of fuelwood to a chip allows the use of standard transport systems designed for the transport of wood chips for the pulp sector. Major technological gains to improve the transport efficiencies of fuelwood are unlikely in the immediate future. The most important improvements are likely to come from efforts to improve carrying efficiencies in pulp chip transport because of the much greater volume and value of this material carried annually. Any developments will be rapidly adopted by those engaged in fuelwood chip transport.

This paper is split into two distinct parts since it addresses two very different crops grown in North America and Europe. In North America short rotation forestry is being developed principally to generate a feedstock for the wood pulping industry and is typically single stem hardwood plantations grown for 6–10 years before harvest. In Europe by contrast, coppiced willow plantations are being grown as an energy crop and harvested on a 3–4 year cycle. In North America, the industry is being driven by the large pulp producing companies; plantations are designed to fit the local conditions and specialist mechanisation is generally not being used. Rather, the companies are using standard agricultural or forestry practices for planting and husbandry and using the crews which already exist to harvest the crop. This paper describes the type of plantations which are being used and the mechanisation which is being applied. In Europe, the coppice crops are grown commercially in Sweden and will shortly be planted on a commercial scale in the UK. In Sweden, the resulting wood fuel is fed into the many wood fired district heating plants and combined heat and power plants. In the UK, the majority of new planting will be used to fire power generation plants working on the gasification principle. Three plants have been given contracts to generate electricity under a premium price scheme and this could result in the planting of 8,000 ha of coppice. Sweden has lead the development of mechanisation for the crop and two harvesters are now considered to be commercial; they are based on existing machines for harvesting forage and sugar cane. Planters are also at the commercial stage of development and machines for weed control have been tested. This paper covers the machinery developments and discusses issues relevant to the mechanisation of the crop such as: whether to harvest as chips or as whole shoots (sticks), the impact of soil compaction, weed control and plantation layout.

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 Report, Biomass as Feedstock for a Bioenergy and Bioproducts Industry: The Technical Feasibility of a Billion-Ton Annual Supply (generally referred to as the Billion-Ton Study or 2005 BTS), was an estimate of “potential” biomass within the contiguous United States based on numerous assumptions about current and future inventory and production capacity, availability, and technology. In the 2005 BTS, a strategic analysis was undertaken to determine if U.S. agriculture and forest resources have the capability to potentially produce at least one billion dry tons of biomass annually, in a sustainable manner—enough to displace approximately 30% of the country’s present petroleum consumption. To ensure reasonable confidence in the study results, an effort was made to use relatively conservative assumptions. However, for both agriculture and forestry, the resource potential was not restricted by price. That is, all identified biomass was potentially available, even though some potential feedstock would more than likely be too expensive to actually be economically available. In addition to updating the 2005 study, this report attempts to address a number of its shortcomings

Group selection is a regeneration harvest method that is being promoted by the USDA Forest Service as an alternative to clearcutting. In a group selection cut, "groups" of trees are marked and harvested in small patches dispersed in a mosaic pattern throughout the timber stand. Group selection has the potential to increase harvesting cost as compared to traditional clearcutting. Three logging systems, a skyline yarder system, a feller-buncher/cable skidder system, and a chainsaw felling/cable skidder system were studied while logging group selection timber sales in the Jefferson National Forest in Virginia. Time study data on the felling and skidding functions were recorded, as well as weekly production and cost data for each operation. Historic clearcutting production was obtained from the study loggers' records for comparison purposes. Group selection unit costs were $39.72, $14.13, and $15.33 per ton for the three systems, respectively. The study systems experienced decreases in production ranging front 17% to 52%. Most of the production decrease was due to an excessive amount of unproductive time directly resulting from the impact of the small, dispersed, multiple-harvest areas on the loggers' normal operating procedure and work flow. North. J. Appl. For. 10(4): 170-174.

A wet pine flat in the coastal plain of South Carolina was harvested with a rubber-tired skidder equipped with 68-in.-wide tires. Soil physical properties were measured immediately before and after a salvage harvest to document changes associated with traffic disturbance. Paired t-tests indicate that the wide-tired operation significantly increased soil volumetric water content, bulk density, and soil strength, and decreased saturated hydraulic conductivity, soil porosity, and depth to the water table. Changes were greatest for the more disturbed areas, and rutting that occurred in the skid trails apparently interrupted subsurface drainage. South. J. Appl. For. 17(1):22-25.

Eight countries collaborated and shared technical information on the harvesting of small trees and forest residues in a three year program. Proceedings and reports from workshops and reviews are summarized in a review of activities and harvesting systems of the participating countries. Four databases were developed for harvesting and transportation of these materials.

Past studies have suggested that processing small diameter whole trees, like those found on rights-of-way (ROWs), would help reduce transportation costs and increase energy value by lowering stem moisture content. Small stems were crushed by a roller crusher/splitter test bench machine and allowed to dry under field conditions in Alabama. Tests were conducted in winter and summer using softwoods and hardwoods. Crushing facilitated short term field drying during periods when rain was light or absent. Any benefits of crushing are realized within the first five weeks of drying. Under field conditions, there is no guaranteed benefit associated with crushing trees to increase the rate of moisture loss over long drying periods or in times of heavy rainfall.

The U.S. Department of Energy (DOE) and the U.S. Department of Agriculture (USDA) are both strongly committed to expanding the role of biomass as an energy source. In particular, they support biomass fuels and products as a way to reduce the need for oil and gas imports; to support the growth of agriculture, forestry, and rural economies; and to foster major new domestic industries--biorefineries--making a variety of fuels, chemicals, and other products. As part of this effort, the Biomass R&D Technical Advisory Committee, a panel established by the Congress to guide the future direction of federally funded biomass R&D, envisioned a 30 percent replacement of the current U.S. petroleum consumption with biofuels by 2030. Biomass--all plant and plant-derived materials including animal manure, not just starch, sugar, oil crops already used for food and energy--has great potential to provide renewable energy for America's future. Biomass recently surpassed hydropower as the largest domestic source of renewable energy and currently provides over 3 percent of the total energy consumption in the United States. In addition to the many benefits common to renewable energy, biomass is particularly attractive because it is the only current renewable source of liquid transportation fuel. This, of course, makes it invaluable in reducing oil imports--one of our most pressing energy needs. A key question, however, is how large a role could biomass play in responding to the nation's energy demands. Assuming that economic and financial policies and advances in conversion technologies make biomass fuels and products more economically viable, could the biorefinery industry be large enough to have a significant impact on energy supply and oil imports? Any and all contributions are certainly needed, but would the biomass potential be sufficiently large to justify the necessary capital replacements in the fuels and automobile sectors? The purpose of this report is to determine whether the land resources of the United States are capable of producing a sustainable supply of biomass sufficient to displace 30 percent or more of the country's present petroleum consumption--the goal set by the Advisory Committee in their vision for biomass technologies. Accomplishing this goal would require approximately 1 billion dry tons of biomass feedstock per year.

The Southern U.S. pulpwood harvesting industry experienced substantial changes in productivity and logging costs from 1979 to 1987. This research measures physical and economic changes in southern timber harvesting and the degree of industry shifting between different levels of harvesting mechanization.

Plantation thinning requires machinery capable of operating in confined conditions while causing minimal damage to the residual stand and site. The Franklin 105 feller buncher, equipped with a Tidewater DL-12 accumulating shear, was studied in a fifth-row thinning application to determine variables affecting machine operation and productivity. Machine operation was divided into two elements: (1) move-to-tree and shear tree; and (2) move-to-dump, dump load, and bunch alignment. Move-to-tree and shear times were influenced by the number of residual trees per acre and whether the operator was row/corridor harvesting or selective thinning, while move-to-dump, dump load, and bunch alignment times were influenced by the average diameter and the number of trees in the shear head prior to dumping. Production costs were higher for selective thinning than for row/corridor harvesting.

Aswing feller buncher was field evaluated for thinning loblolly pine on terrain from level to 58% slope. Production estimates were developed for the machine to operate up, down, and across slopes and on level ground. Also, the effect of piling to the front and to the rear was examined in all the models. The time required to fell and bunch a tree proved to be dependent on tree size and stand density. Production was also affected by the direction of travel and placement of the bunches.

Small grapple skidders working on two thinning operations in the Atlantic coastal plain were examined. When gate delimbing was used, production per PMH was reduced from 11.47 cords to 7 85 cords—a reduction of 32%. This reduction in skidder productivity was compensated by a reduction in total production cost per cord because of the high cost of manually delimbing trees. With increases in insurance rates for labor-intensive operations continuing to rise dramatically, gate delimbing systems should continue to be competitive. South., J. Appl. For. 12(4):243-246.

Atwin-cylinder chainsaw was evaluated to determine the vibration levels transmitted to the operator. The saw vibration was compared with two different types of single-cylinder saws in a static bench test and in a dynamic bucking test. The tests showed a significant reduction in vibration at the handles of the twin-cylinder saw model as compared to the single-cylinder saws.

A continuous-speed felling and bunching prototype machine was evaluated in harvesting a three-year-old, short-rotation sycamore plantation. A small tractor, grapple skidder, and large chipper were evaluated along with the prototype machine as complete harvesting systems. Prediction equations, production rates, and costs were developed for each component of the systems. Production of the feller buncher was about 850 stems an hour (17·3 green Mg), and felling cost for the test was $3·29 green Mg−1. Total system cost was about $11·50 green Mg−1. However, cost could be reduced with a smaller chipper. A survey of stump damage showed little damage from the feller buncher when it was operating properly. The tractor caused minimal skidding damage, less than that of the large skidder.

THREE Albright Model 36 felling saws and three dif-ferent rubber-tired carriers were evaluated over a range of stand and terrain conditions in the southeastern United States. The Albright felling saw is a hydraulic-ally-driven saw chain attachment mounted on the front of a carrier for directional felling of saw timber. The ob-jective of the study was to determine the productivity rate of this type of felling saw. Average felling time was 1.124 min per tree. Average element times for a production cy-cle was 0.410 min for movetime between trees and 0.714 min for positioning and sawing a tree. Prediction equa-tions were developed for these elements.

INTRODUCTION The machine was part of a shortwood operation in a dense, 20-year-old pine stand that was being clear cut. The harvesting system was comprised of a Drott 40 feller buncher, a Hydro-Ax 511 feller buncher, the skidder flail, and a Barko Loader with a slasher. The skidder either skidded bunches and flailed at the deck or flailed bunches in the woods and then skidded. Trees delimbed at the deck were placed onto the slasher with the loader and bucked into shortwood. Trees delimbed in the woods were skidded to the deck and processed with the slasher. The shortwood was loaded onto set-out trailers.

The Mor-Bell logger’ is a recently introduced machine with a trianglar (3 wheel) configuration. It has several possible applications in timber harvesting. Although originally designed for loading sugarcane in South Africa, the converted machine can be used in forestry operations to skid, load, unload, prebunch, or feed a chipper. The ,logger is being marketed to interface with existing harvesting equipment such as between a feller buncher and skidder or skidder and processor. Taylor (1978) evaluated the logger as a pulpwood forwarder in coniferous thinning systems in South Africa. He found that overall simplicity, ‘low operating costs, maneuverabil i ty, and high production capacity for its size made it a very useful machine. The objective of this study was to determine the skidding production rates for the Mor-Bell logger during a thinning application. Although the logger is not designed specifically for skidding, it is impor