Search

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...

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.

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.

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.

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.

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.

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.