Biological and Agricultural Engineering

Forest and Fiber Engineering

Research in forest engineering focuses on development of techniques, management strategies, and equipment that are appropriate for California’s unique situation. While the state ranks near the top in the US in wood production, and forestry is a large industry, most residents live far from forests and view them as natural preserves rather than resource producers. Therefore, while forest operations such as harvesting must be economic, they must also meet increasingly rigorous standards of environmental and aesthetic quality. California’s timber base is diverse; major timber types include redwood, ponderosa pine, and Douglas fir—some of the most valuable conifer species in the US.

Much of California’s forest land has relatively rugged terrain. Cable logging, using a winch and wire rope cables to transport trees to a haul road, has displaced skidder logging on these lands to achieve lower levels of soil disturbance than would be possible with rubber-tired skidders or crawler tractors. Visual guidance systems for yarder operators, guyline tension monitors, artificial cable anchors, and cable towed vehicles are examples of several recent projects that address steeper terrain.

Fire suppression in California’s forests over the last hundred years has resulted in unintended consequences: high fuel loadings and therefore high probabilities of catastrophic crown fires, overstocked stands where trees of poor vigor are susceptible to insect attack and/or drought, and low growth rates for individual trees. We are testing harvesting operations that might solve the forest health problems. Our multidisciplinary efforts involve assessments of the impacts of various harvest systems on soils, habitat, reserve trees, and economics.

Because of changing demands on the forest resource and increased understanding of forest ecology, opportunities exist to improve current practices by developing better equipment. As an example, broadcast burning was commonly used to prepare harvested areas. for replanting. Recent studies have shown the benefits of retaining some organic matter and have highlighted problems of excessive temperatures on soil. These results, along with concerns about air pollution, have prompted us to develop equipment for preparing planting sites and recovering some of the larger residues for energy.

To offset reductions in harvesting from native forests, companies are establishing short-rotation plantations to provide fiber and energy. These plantations are essentially perennial agricultural crops, and new equipment and processing methods are being investigated for efficient utilization of these new resources.

Faculty and students based at the Forest Products Laboratory (FPL) in Richmond are involved in research to nondestructively evaluate wood-based materials. Ultrasound and acoustic emission are being employed to evaluate biodegradation of utility poles, decay in glulam beams, to detect termites in structures, and to understand the creep-rupture process for oriented strandboard siding.

FPL researchers are also studying fire at the urban-wildland interface. They are developing test methods for vegetation and structures, and models to evaluate fire hazards to housing and identify possible mitigation steps.

Research in fiber engineering focuses on analyzing, measuring, and improving the physical properties of fibers, fabrics, and fiber composites, as well as on conversion of agricultural wastes into useful products.

Manufacturers need to predict the strength of fibers and fiber structures. Our faculty and their students are developing models to characterize the mechanical behavior of yarns and fabrics as functions of fiber properties. Their results have improved the understanding of the properties of products such as diapers, papers, and non-woven fabrics. They are also studying aspects of fiber reinforced composite materials, such as compatibility between fibers and matrix materials, and stress-strain relationships for hybrid composites.

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Cloned eucalyptus are grown in northern California to produce paper, fuel, and possibly other wood products. Our research focuses on tree management and harvesting proce-dures. The time between planting and harvest is about eight years.

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This forwarder is one element of a low-impact harvesting system which is being evaluated in the Sierra Nevada for reducing fire danger and improving forest health while retaining old-growth stand structure for wildlife habitat.

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This ponderosa pine plantation has been properly thinned to reduce fire danger, reduce the severity of insect attack, and improve growth rates. Products from forest thinnings with low-impact harvest operations include sawlogs for milling into lumber and smaller logs for paper production or biomass fuel.

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The structural properties of natural and man-made fibers are important for developing textiles and other fibrous materials such as paper products and construction materials. This instrument is used for determining strength properties of the fibers and composites.