Treesearch

Antagonistic characteristics of a commercial biofungicide, Trichoderma (Gliocladiurn) virens (GL-21, W. R. Grace and Co., CT), were evaluated against three white-rot fungi, Trametes versicolor, Phlebia brevispora, Irpex lacteus, and three brown-rot fungi, Postia placenta, Neolentinus lepideus, and Gloeophyllum trabeum. In dual cultures of T. virens and wood decay fungi, T, virens rapidly overgrew and killed the decay fungi. Pretreatment of Southern Pine and maple blocks with T. virens prevented weight loss by all decay fungi in the soil-block tests. T. virens colonized blocks, treated with...

Kraft and thermomechanical (TMP) pulps were prepared and evaluated from lodgepole pine and mixed Douglas-fir/western larch sawmill residue chips; lodgepole pine, Douglas-fir, and western larch submerchantable logs; and lodgepole pine, Douglas-fir, and western larch small trees and tops. Kraft pulp from small trees and tops was identical to that from submerchantable logs, except for Douglas-fir submerchantable logs. Lodgepole pine showed higher yield than western larch at the same target kappa levels. The handsheet properties of western larch from different raw material sources were the...

The goal of this research was to develop nondestructive evaluation (NDE) technology to enhance mechanical stress rating of lumber. An ultrasonic NDE technique was developed that is sensitive to grain angle and edge knots in lumber - two primary determinants of lumber strength. The presence of edge knots increased the acoustic wave travel time and selectively attenuated the higher frequency ultrasonic energy. NDE measurements and tension tests were performed on 200 pieces of nominal 50 × 150 mm Southern Pine lumber. Statistical models were developed from localized stress wave indices to...

In studies on wood strength, researchers sometimes replace experimental unit allocation via random sampling with allocation via sorts based on nondestructive measurements of strength predictors such as modulus of elasticity and specific gravity. This report documents TT, a computer program that implements recently published methods to increase the sensitivity of such bpredictor sortc experiments. The report consists of annotated keyboard sessions and computer output from runs of TT.

The presentations at this symposium discussed concepts of ecosystem management and sustainability as viewed by various levels of government and private land managers. The theme was to integrate ecology, silviculture, forest operations, wood products, and economics to find ways to develop healthy sustainable ecosystems under financially sound management practices. Speakers discussed ways to manage disturbance to create landscapes with the desired level of diversity and resilience to fire, disease, and insects. Others identified technical aspects of improving the options for producing wood...

This report describes 52 taxa of North American softwoods, which are organized alphabetically by genus. Descriptions include scientific name, trade name, distribution, tree characteristics, wood characteristics (e.g., general, weight, mechanical properties, drying, shrinkage, working properties, durability, preservation, uses, and toxicity), and additional sources of information. Data were compiled from existing literature, mostly from research done at the U.S. Department of Agriculture, Forest Service, Forest Products Laboratory, Madison, Wisconsin.

Structural and nonstructural panels have been the fastest growing sector among wood products for the past two decades. The recent spate of plant construction and drop in product prices indicate slower growth and consolidation in the next 2 years. Growth in demand is unlikely to catch up with projected capacities until the next century, unless attrition of some existing capacity reduces industry growth. Among structural panels, costs of production are lowest for oriented strandboard, but there is a wide range among plants. Plywood costs are lowest in the U.S. South and highest in the West....

Longitudinal stress wave and transverse vibration nondestructive testing (NDT) techniques have proven to be accurate means of evaluating the quality of wood based products. Researchers have found strong relationships between stress wave and transverse vibration parameters (e.g., wave velocity and modulus of elasticity predicted using NDT measurements) with the actual static bending properties (e.g., modulus of elasticity from static bending tests) of d y as well as green wood based materials. Therefore, these techniques may be used to presort or grade structural wood prior to drying,...

The numerical solution to the frequency equation for the transverse vibration of a simple beam with symmetric overhang is found. The numerical results converge to the analytical solutions for the two limiting cases of a beam with no overhang and a beam with no span and agree with the case in which the supports are at the nodal points of a freely vibrating beam. An approximation to the solution of the frequency equation for beams with small overhang is presented and compared to the numerical solution. This simple yet accurate approximation is most useful to determine a beamas flexural...

This study reviewed the literature on experimental and analytical research for the connection of wood members using multiple laterally loaded bolts. From this, the influence of geometric factors were ascertained, such as staggered and aligned fasteners, optimum fastener configurations, row factors and length-to-diameter bolt ratios, spacing, end and edge distances, and the effect of mixed types and sizes of fasteners and eccentric loading. Areas of additional research needed on multiple-bolted joints in wood members are identified.