Eini C. Lowell

Physical and mechanical properties of young-growth Douglas-fir and western hemlock from western Washington.

Diversity in land management objectives has led to changes in the character of raw material available to the forest products industries in the US Pacific Northwest. Increasing numbers of logs from small-diameter trees, both plantation grown and those from suppressed or young stands, now constitute a large proportion of logs coming into the mill yard. Wood coming from plantations or young stands has different properties than wood coming from older, suppressed stands. This research examined wood properties of small-diameter plantation-grown Douglas-fir and western hemlock with the goal of a better understanding of utilization of small-diameter, fast-grown trees for use in manufacturing engineered wood composites. Twelve trees of each species were harvested and three bolts cut from each tree. Each bolt provided samples for X-ray densitometry profiles, compression, and tension parallel to grain and flexure tests. Both species were found to have a very high proportion of juvenile wood. Most wood properties dec...

Hot water extracted wood fiber for production of wood plastic composites (WPCs)

Abstract Undebarked ponderosa pine chips were treated by hot water extraction to modify the chemical composition. In the treated pine (TP), the mass was reduced by approximately 20%, and the extract was composed mainly of degradation products of hemicelluloses. Wood flour produced from TP and unextracted chips (untreated pine, UP) was blended with high-density polyethylene (HDPE) and polypropylene (PP) and was extruded into wood plastic composites (WPCs). Formulations for WPCs consisted of 58% pine, 32% plastic, and 10% other additives. WPC based on HDPE+TP and PP+TP absorbed 46–45% less water than did WPC based on HDPE+UP and PP+UP, respectively. Thickness swelling was reduced by 45–59%, respectively, after 2520 h of immersion. The diffusion constant decreased by approximately 36%. Evaluation of mechanical properties in flexure and tension mode indicated improvements in TP-WPC properties, although the data were not statistically significant in all cases. Results showed that debarking of ponderosa pine is not required for WPC production.

Effect of hot water extracted hardwood and softwood chips on particleboard properties

Abstract The affinity of particleboard (PB) to water is one of the main limitations for using PB in moisture-rich environments. PB dimensional stability and durability can be improved by reducing the available hydroxyl groups in wood through hemicellulose removal, for example, by hot water extraction (HWE), which increases wood resistance to moisture uptake. The resulting liquid fraction from HWE is rich in hemicelluloses and can be used for chemicals and fuels, and the solid fraction is less hydrophilic. The objective of this study was to investigate the effects of HWE of softwood chips (conducted at 160°C and 90 min) and hardwood chips (160°C and 120 min) on the properties of PB panels. HWE increased compressibility and reduced springback by 34% and 44% for pine and maple chips, respectively, which positively impacted the PB properties. Water absorption of pine PB panels was lowered by 35% and that of maple PB panels by 30%, while reduction of thickness swelling was lowered by 39% for pine PB and 56% for maple PB after 24 h of immersion in water. The mechanical properties were not significantly affected.

Managing for wood quality.

During the 20th century, the Pacific Northwest (western Oregon and Washington, coastal British Columbia, and southeastern Alaska) produced some of the highest quality timber in North America. Forests were old and trees were large; wood products from this region were easily distinguished from those made from timber produced in other regions in North America. In some cases, the timber had unique visual characteristics; its slow growth produced clear wood and tight grain patterns and its superior mechanical properties were prized. The sheer size of the trees made it possible to manufacture extremely large pieces. Early in the century, Douglas-fir trees (Pseudotsuga menziesii (Mirb.) Franco) (at the time also known as Oregon pine) that were tall and cylindrical possessed a stiffness that made them valuable as ships’ masts (Allin 1995). Later, these same characteristics made this species important as electric power transmission poles. Long spans, made possible by the high strength and stiffness of Douglas-fir, allowed architects to create distinctive open interior spaces. Several mills specialized in beams up to 185 feet (57 meters (m)) long and several feet deep. The fine grain and infrequent knots in large old trees permitted manufacture of clear, straight-grained moulding and millwork that was valued around the world in door and window manufacturing. The high strength-to-weight ratio of Sitka spruce (Picea sitchensis (Bong.) Carr.) was attractive to early airplane manufacturers and to musical instrument craftsmen who valued the tonal quality derived from its straight, even grain (Burns and Honkala 1990).

Interrelationship between lignin-rich dichloromethane extracts of hot water-treated wood fibers and high-density polyethylene (HDPE) in wood plastic composite (WPC) production

Abstract Hot water extraction (HWE) partially removes hemicelluloses from wood while leaving the majority of the lignin and cellulose; however, the lignin partially migrates to the inner surfaces of the cell wall where it can be deposited as a layer that is sometimes visible as droplets. This lignin-rich material was isolated via Soxhlet extraction with dichloromethane to investigate its rheological behavior in blends with high-density polyethylene (HDPE), a common material in wood plastic composites (WPCs). Pyrolysis gas-chromatography/mass spectrometry (Py-GC/MS) and electrospray ion mass spectrometry (ESI/MS) confirmed that the isolated material is constituted mainly of low-molecular-weight lignin oligomers. The blends of HDPE/isolated lignin, in varying ratios, were tested by means of dynamic rheology. A “shoulder” was found in plots “shear storage moduli (G′) vs. frequency sweep” and a shift of the terminal zone to lower frequencies was observed. Apparently, this shoulder is caused by the elastic contribution of the interfacial tension between the blend components. The rheology of WPCs produced from HWE wood and HDPE shows a similar shoulder in G′ plots, suggesting that the HDPE/lignin blends are in part responsible for the shape of the G′ curves.

User guide for HCR Estimator 2.0: software to calculate cost and revenue thresholds for harvesting small-diameter ponderosa pine.

Becker, Dennis R.; Larson, Debra; Lowell, Eini C.; Rummer, Robert B. 2007. User guide for HCR Estimator 2.0: software to calculate cost and revenue thresholds for harvesting small-diameter ponderosa pine. Gen. Tech. Rep. PNW-GTR-748. Portland, OR: U.S. Department of Agriculture, Forest Service, Pacific Northwest Research Station. 51 p. The HCR (Harvest Cost-Revenue) Estimator is engineering and financial analysis software used to evaluate stand-level financial thresholds for harvesting smalldiameter ponderosa pine (Pinus ponderosa Dougl. ex Laws.) in the Southwest United States. The Windows-based program helps contractors and planners to identify costs associated with tree selection, residual handling, transportation of raw materials, and equipment used. Costs are compared against total financial return for regionally based market opportunities to arrive at potential net profit. Information is used to identify per-acre cost thresholds, for contract appraisal, and for prioritizing project planning for wildfire fuel reduction treatments and forest restoration efforts.

Opportunities and Challenges of Utilizing Small Diameter Timber from Fuel Reduction Thinning Programs

Trees being removed in fuel reduction treatments are often smaller in diameter than those historically removed in a timber harvest. There are many opportunities to use this material but the resource characteristics must match the final product and the manufacturing method at the appropriate scale of the local community. Research has shown this material is suited for a number of products ranging from structural lumber (small diameter trees coming from suppressed stands appear to have properties similar to old growth), to cut-stock (clear cuttings), to roundwood products (posts and poles). Using emerging technology to capture as much value from this resource as possible is key in offsetting treatment costs. Challenges associated with these treatments include peoples’ conflicting expectations for forested landscapes, the economics of harvesting and hauling this material using the existing infrastructure, and the tradeoffs of performing these activities where they are most needed.

Next-Generation Products and Greenhouse Gas Implications

The social and economic benefits of wood harvest from forests depend on the demand for different ecosystem services, including products desired from trees. Although uses of species such as Douglas-fir and western hemlock for finished lumber, plywood, and paper have dominated past demand in moist coniferous forests of the Pacific Northwest, the emergence of new uses and technologies has expanded opportunities for wood utilization. This changes what, when, and how wood is harvested from the forest and how different management activities may intersect with restoration targets and ecosystem services—some of which are only just emerging.

Wood Quality of Old-Growth Koa Logs and Lumber

Abstract Acacia koa trees are ecologically, economically, and culturally significant to the Hawaiian Islands. Koa wood is one of the most valuable species in the world and sale of koa products represents a majority of all the Hawaiian wood products sold by Hawaiian retailers. Today, there is concern in Hawaii among foresters, forest landowners and managers, wood products manufacturers, and the public that the remaining old-growth koa resource has become scarce, is suffering from declining health and diseases, and is characterized by poor growth form. Current practices require harvest of only dead and dying trees and using downed material in wood products manufacturing. We examined lumber volume and value recovery from logs sawn from dead and dying trees and from relic logs (logs that have been on the ground) from four sites on the island of Hawaii. Gross lumber recovery from all study logs was 71 percent. Log size did not significantly influence lumber volume recovery. Forty-five percent of the lumber man...