Research Highlights
Helping Western Rural Communities Through Use of Small-Diameter Trees
Overgrown, dense forests in the inland West of the United States need thinning
of small-diameter trees to reduce the risk of catastrophic fires and disease
outbreaks. FPL research has demonstrated that high-value products can be produced
from these small-diameter thinnings. For example, Douglas-fir flooring is worth
six times as much as the rough, small-diameter timber it was made from. Researchers
have provided technical assistance with grading, drying, manufacturing, and
economic feasibility for various rural, forest-based communities, and the results
have been successful. In Hayfork, California, a small business that produces flooring,
veneer, furniture, and lumber from small-diameter Douglas-fir has expanded.
A Catron County, New Mexico, large-diameter sawmill is retooling so it can
process small-diameter trees and hopes to begin offering those services in 2001. Also,
FPL researchers built a demonstration structure that highlights the uses of
small-diameter round ponderosa pine timbers, and the researchers have worked
with several communities to help them implement these techniques. The La Madera Forest Products Association
in Vallecitos, New Mexico, is developing a small enterprise that will produce
sheds and farm structures from small-diameter roundwood. A Navajo community
in Flagstaff, Arizona, built a hogan using the same resource. Also, the Salt
Lake City, Utah, area will soon construct small-diameter roundwood kiosks for the
2002 Olympics.
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Improved Utilization of Small-Diameter Ponderosa Pine in Glued-Laminated Timber
Many forest stands in the Western and Southwestern United States are densely
populated with ponderosa pine (Pinus ponderosa) and need thinning to reduce
the fire hazard. Because of the poor structural properties of ponderosa pine,
current glued-laminated timber (glulam) standards only allow ponderosa pine
in the core laminations of glulam beams (approximately 50% of the cross section),
where the stresses are low. To use more ponderosa pine, FPL researchers are
evaluating glulam made entirely from lumber sawn from this small-diameter timber
resource. They mechanically graded ponderosa pine lumber and developed some
E-rated grades that assured the stiffness performance of this material (E-rated
lumber meets criteria for use in glulam that are usually more restrictive than
those applied to framing lumber, but the lumber does not require destructive
tests). Strict edge-knot criteria were also applied to these grades to assure
adequate strength performance. With these grades of lumber, researchers developed
an efficient combination of glulam that had E-rated lumber in the outer laminations
and visually graded lumber in the core laminations. Ponderosa pine glulam beams
made from these grades of lumber are expected to perform approximately 20%
higher for bending stiffness and approximately 40% higher for bending strength
than glulam combinations available from current standards. The testing and
analysis of this glulam combination will show that strict mechanical grading
will allow ponderosa pine to be used in all portions of the glulam beam cross
section with predictable performance. By demonstrating that small-diameter
ponderosa pine timber is a viable source for laminating stock, this research
will expand the available markets for small-diameter material.
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FPL research engineer Roland Hernandez inspects
a ponderosa pine glulam beam tested in tension. These tension tests--where
beams are loaded to failure in the lengthwise direction--are the only
tests of their kind being conducted in the United States. These beams
are averaging over 100,000 lb of load, which is twice the design value
currently specified. Results of these test will allow designers to
make more efficient use of this material in structures. |
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Degradation of Slash Associated With Silvicultural Thinning for Fire Control
Although removal of small-diameter timber from overstocked Western U.S. forests
reduces the fire hazard, it also weakens the soil. To return nutrients to the
soil, a portion of slash (the debris left over after a logging operation) must
be left in the field. Leaving slash increases the fire hazard again, but once
the slash begins to decay, the fire hazard decreases substantially. As a way
of maximizing the return of nutrients to the soil while minimizing fire hazard,
FPL researchers are finding ways to speed up natural decay processes. In the
preliminary phase of this research, they inoculated logs with local decay fungi
to study host-fungus interaction. Two of the three fungi species started decaying
the log. FPL researchers are also cooperating with the Forest Service's Forestry
Sciences Lab in Moscow, Idaho, where they are watching how slash naturally
degrades as a result of different thinning techniques. Future research will
involve inoculating different types of fungi on slash, including those that
will grow into edible and medicinal mushrooms. These mushrooms typically grow
on hardwoods, so researchers will evaluate whether they can thrive on softwood
slash, thereby creating another value-added product for small-diameter timber.
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Automated Lumber Scanning Technology
Accurately determining the strength and soundness of wood is important for
economy and safety, but the traditional mechanical methods for testing these
properties damage or destroy the wood. In cooperation with several Forest
Service research stations, State and Private Forestry, and private industry,
FPL researchers have developed a nondestructive evaluation (NDE) system as
an alternative to mechanical testing. The NDE system incorporates a variety
of techniques to reveal decay, fungi, or other defects in lumber. One technique
that has received considerable attention for scanning wood is sending high-speed
ultrasound through high-quality lumber. The ultrasound is very sensitive
to naturally occurring defects, much more accurate than visual scanning,
and results in considerable savings in raw material. Based on FPL's research
efforts, this technology is being commercialized to scan high-quality lumber
for defects. NDE has many applications: evaluating the properties of standing
timber, detecting infestation in green lumber, and testing structural members
in a home. In addition to accurately monitoring the condition of wood in
use, this technology also helps extend the forest resource by optimizing
the kiln drying process, thereby saving energy and increasing the effectiveness
of the lumber drying process.
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Value-Added Structural Components From Underused Hardwoods
Hardwoods are abundant in the forests of the Northeastern United States, but
past forestry practices have resulted in an excess of low-valued hardwood
species such as red maple. Numerous stands of hardwood forests around the
Lake States and the Northeast need active management to restore desired conditions,
the original balance of species, and a greater biodiversity of trees, plants,
and animals. The removal of low-valued hardwoods is expensive, and pallets
traditionally made from this material do not cover the costs. FPL researchers
are working in cooperation with Michigan Technological University, the University
of Minnesota's Natural Resources Research Institute in Duluth, and several
industry partners to develop value-added structural uses for red maple and
to find economical uses for manufacturing residuals from hard maple and yellow
birch. Research has included financial assessments and studies on cost-effective
drying, engineering properties of the underused species, lumber yields, fasteners,
and designs for I-beams and trusses. Research results show that maple trusses
have 29% more strength and 10% more stiffness than equivalent softwood trusses.
These new uses for low-valued hardwoods will offset the costs of their removal
and the reforestation of other species, which will restore biodiversity.
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Using Wood and Agricultural Fibers to Clean Water
Much of the water available and renewable in rivers and lakes for human and
agricultural use is polluted and needs to be cleaned before use. An estimated
90% of all Americans live within 10 miles of a body of contaminated water.
FPL researchers have learned that filters made from wood and agricultural
fibers can remove significant levels of contaminants such as heavy metals,
oils, pesticides-herbicides, and phosphates-nutrients from water. They have
also concluded that filter efficiency can improve by simple chemical modification
of the fiber. For example, treating Douglas-fir fiber with nitric acid improves
the absorption of the filter several times. Filters made with wood and agricultural
fibers are being used in the Wayne National Forest to remove heavy metals
from a stream contaminated by a mine, thus reducing its acidity. Another
filtration system made with these fibers is removing heavy metals from parking
lot runoff before it enters a Wisconsin lake. In the spring of 2001, filters
designed to remove phosphorus will be placed in the New York City watershed,
which supplies water to more than 9 million people. FPL researchers will
continue to evaluate the effectiveness of many wood and agricultural fibers
in filters. This knowledge could increase the chances that communities with
polluted water will be able to use locally available fibers in their filtration
systems.
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Environmental Impact of Preservative-Treated Wood
Used in Sensitive Ecosystems
Watershed management sometimes comes into conflict with the need to provide
commercial and recreational access to our National Forests. For example, bridges,
boardwalks, piers, viewing platforms, and other structures often must be built
over streams, lakes, and wetlands. These structures are frequently built with
preservative-treated wood because it is an economical, durable building material
that visually blends with the outdoor environment. However, many of these structures
are placed in pristine or sensitive ecosystems where release of significant
amounts of wood preservative components could impact the environment. Accordingly,
a study to evaluate preservative leaching and environmental impacts was developed
through the cooperative efforts of the Forest Products Laboratory, Mt. Hood
National Forest, the Bureau of Land Management, and the wood treating industry.
FPL evaluated the effects of treated wood on the environment from a wetland
boardwalk project that included four representative types of treated wood.
The project was considered "worst case" because the site had high rainfall
and a large volume of treated wood had been used. Each type of treated wood
released measurable concentrations of preservative elements into the soil and
sediment, although high concentrations were generally found only in very close
proximity to the boardwalk. In some cases, preservatives were also detected
in the water samples removed from the wetland. However, the levels detected
did not have any measurable impacts on the more than 97 genera of aquatic invertebrates
in the wetland. These findings indicate that, in most cases, preservative-treated
wood does not pose a hazard to sensitive environments. Researchers will conduct
the five-year inspection of the project site in the summer of 2001 and will
continue to monitor it for leaching. Since measurable releases of preservative
components did occur, the researchers will publish guidelines that can be used
by forest and watershed managers for selecting, specifying, and using treated
wood to minimize environmental impacts.
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Fungal Degradation and Remediation of Preservative-Treated
Waste Wood
An estimated 60 million board feet of wood products treated with the preservative
chromated copper arsenate (CCA) have been placed in service since the early
1970s. This wood, along with products treated with ammoniacal copper quat (ACQ),
creosote, and pentachlorophenol, will be removed from service in the near future.
Because CCA-treated wood is recognized by the U.S. Environmental Protection
Agency as a nonhazardous material, nearly all of it is discarded in approved
landfills. Waste management systems are needed to address this growing waste
wood problem. FPL researchers have developed bioprocessing strategies using
fungi and bacteria that degrade the waste wood, remove the toxic metals, or
degrade the toxic preservatives. For example, bioremediation with common soil
bacteria has been shown to remove significant amounts of copper, chromium,
and arsenic from CCA-treated wood. This process essentially cleans the preservative
from the wood so that the wood can be recycled into composite products. So
far, FPL researchers have produced four patent applications for bioremediation
methods using fungi. In the future, they will improve techniques for bacterial
remediation and scale up the size of their test projects. Successfully degrading
or recycling treated waste wood will extend our landfill space, reduce the
potential for soil contamination, and possibly offset timber harvest by an
estimated 500 million cubic feet per year.
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Building Deconstruction and Engineering Evaluation of
Reclaimed Lumber
According to the U.S. Environmental Protection Agency (EPA), more than 200,000
buildings in the United States are torn down annually. Because many of these
are wood framed, millions of board feet of dimension lumber is landfilled every
year. Although there is great potential to salvage this structural lumber for
new home construction, no standards exist for regrading and reuse. At FPL,
engineering studies are underway to test reclaimed lumber for stiffness and
strength. FPL researchers will compare test results to databases for new lumber.
With their findings, regrading and reuse standards will be developed. The effects
of nail holes and other damage on lumber strength are also being evaluated.
This research will improve the marketability of reclaimed lumber and assure
its suitability for reuse. In addition, FPL researchers, along with several
partners, are working to encourage the use of building deconstruction (or building
dismantlement) as an alternative to building demolition at U.S. Army bases.
Working with the U.S. Army, the U.S. Army Corps of Engineers Construction Engineering
Research Laboratories, the University of Florida, the EPA, and Habitat for
Humanity, building deconstruction is being evaluated at the Badger Arsenal,
Wisconsin; Fort Chaffee, Arkansas; Fort Hood, Texas; and Fort McCellan, Arkansas.
One potential opportunity is for millions of board feet of lumber available
in excess buildings at these bases to be utilized by Habitat for Humanity for
the construction of low-income housing.
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Material Properties of Woodfiber-Plastic Composites
Although broken-down pallets, sawdust, and wood chips are normally thought
of as waste wood, FPL researchers are using these materials to enhance plastics.
Industry has traditionally added filler to plastics to reduce raw material
cost and improve the properties of their products. Waste wood can be ground
into wood flour or broken down into wood fibers to serve as filler for plastics.
Using wood flour or fiber as a filler has unique advantages. It is an economical,
readily available material that gives finished products a wood look. And,
although it provides similar benefits as other fillers, its relatively low
density makes products lighter than those made with other fillers. Woodfiber-plastic
composites are currently used for car door interiors in the automotive industry.
Rapidly growing markets for composite products include roof shingles, decking,
and window and door components. Recycled plastics are also a component in
some of these items. Researchers at FPL are evaluating how varying the ingredients
and processing methods for woodfiber-plastic composites affects the properties
and performance of the finished product. For example, they are examining
the effects of using different types of plastics, additives, and fibers.
This research could lead to woodfiber-plastic composites with improved performance
that are also more cost-effective. These characteristics will make the composites
suitable for a wider variety of end uses and enable industry to use more
recycled plastics and waste wood.
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Producing Composite Signs Using Juniper Fibers
An overabundance of juniper in the Southwestern United States is causing damage
to the grassland ecosystem. The tree's wide, deep roots lower the water table,
which prevents shallow-rooted grasses from surviving. This loss of grassland
causes erosion and water pollution. Since juniper is a low-value wood, researchers
at FPL have been looking for uses that will make its removal economically
worthwhile. They have learned that juniper fiber works well when mixed with
recycled thermoplastics in woodfiber-plastic composite products. Juniper-plastic
composite highway signs, route markers, and informational signs made by the
researchers have been placed in the Cibola and Kaibab National Forests, where
they will be monitored for several years. Preliminary results of this field
testing show that the signs have good dimensional stability and are highly
resistant to water. P & M signs, a small business in a rural community in
New Mexico, has been working with FPL to commercialize this technology. The
company is obtaining the equipment needed to make the signs and hopes to
be in production by summer 2001.
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New Generation of Pressure Sensitive Adhesives
FPL has been working with the U.S. Postal Service (USPS), adhesive manufacturers,
papermakers, and equipment manufacturers to develop and test an environmentally
benign pressure sensitive adhesive (PSA) that can be used for stamps, envelopes,
labels, and stickers. Historically, the problem with this type of adhesive
has been removing the PSA "stickies" from recycled mixed office waste to
keep them from being deposited on the recycling equipment and in the recycled
paper, which adversely affects the paper production process and quality of
the paper. Pilot tests of the new PSA showed that the stickies could be separated
from the rest of the mixed office waste, which makes recycling easier. Twenty
mill trials at six U.S. paper mills have endorsed the findings of the pilot
testing. As a result of the successful mill trials, the USPS eventually plans
to use only the new PSA in the more than 40 billion PSA stamps they produce
annually. The new PSA has the potential to allow up to 20 more tons of mixed
office wastepaper to be recycled annually in the U.S. The next phase of this
research project may help keep even more paper out of landfills by studying
the liners that store the stamps. The silicone in the liners causes problems
in the paper-recycling process especially in mills producing printing and
writing recovered paper. In addition to cooperating with its partners for
the PSA stamp, FPL researchers will work with liner-makers to develop and
test an easily recyclable liner.
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Papermaking with Polyoxometalates: Better Bleaching and
Pulping
Papermaking processes often are not environmentally benign. Mills usually pulp
wood with sulfur compounds, which produce an unpleasant smell and release sulfur
dioxide into the atmosphere. Sulfur dioxide can cause acid rain, which can
damage soils, forests, aquatic life, and human health. Traditional bleaching
processes use large amounts of water and energy and generate chlorinated organic
compounds and large volumes of wastewater. FPL researchers have developed alternative
processes for producing pulp fibers from wood and bleaching them. They are
based on using highly selective inorganic enzyme analogs to separate the cellulose
fibers from other wood components. These analogs are the polyoxometalates (POMs),
a class of metal oxide anions similar to many mineral ores. When applied in
their active state, POMs can oxidize lignin in wood or pulp while leaving the
cellulose undamaged, which permits the bleaching or pulping of several species
at once. This capability allows for the effective pulping and bleaching of
small-diameter, mixed-species material, which has not been possible with traditional
bleaching or chemical (kraft) pulp manufacturing technology. Furthermore, reactivation
of the POMs with oxygen under certain conditions after bleaching catalyzes
oxidation of the organic byproducts to carbon dioxide and water. Thus, POMs
have the potential to provide a cost-effective option for a closed-cycle mill
system, which produces virtually no effluent and saves chemical feedstock,
energy, and water. Researchers are beginning engineering studies that will
help them design a pilot demonstration of a closed-cycle bleach plant that
uses POMs. They are also optimizing a pulping process combining soda pulping
and POMs that does not have the harmful effects of sulfur pulping and produces
a higher yield. Properties of paper produced from POM-bleached pulps match
those of ECF (chlorine-dioxide-based bleaching technology) pulps and are superior
to TCF (total chlorine-free bleaching process) pulps. Researchers expect that
the POM-soda pulp will produce high-quality paper as well. In addition to making
paper more efficiently and with less harm to the environment, implementation
of POM technology will also allow paper mills to use the diverse small-diameter
timber resource more effectively.
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Beetle-Killed Spruce Utilization
In Alaska's Kenai Peninsula, the Dendroctonu rufipennis beetle has attacked
trees, leaving large stands of dead and dying timbers, many of which are
spruces. Since these damaged timbers cannot be used as structural components,
FPL researchers conducted tests to evaluate the pulpability of the beetle-killed
spruce. They pulped and tested four classes of logs that ranged from infested
but still living at harvest to those that had been dead for a long time.
Researchers learned that the wood can be pulped and that it has the potential
to make paper as high in quality as that made from noninfested trees. The
extent to which the trees had deteriorated did not significantly affect pulpability
or paper properties. These results will probably encourage industry to consider
nontraditional species for pulpwood, leading to more effective use of the
forest resource.
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Evaluating Performance of Hardboard Lap Siding
Reducing the need for frequent replacement of wood is an important aspect of
effective wood utilization. FPL is helping extend the service life of wood
with its research on hardboard lap siding. Performance problems with this
siding in southern Florida have been so extensive that the U.S. Department
of Housing and Urban Development proposed a local standard requiring prefinishing
and priming of all siding surfaces, including the back. To evaluate the effect
of these practices, researchers exposed hardboard lap siding on two test
buildings in Delray Beach, Florida, for 29 months. Half of the siding was
back-primed and half was not. After inspecting and determining the final
moisture content, researchers found no evidence that either back-priming
or prefinishing reduced moisture content of this particular type of siding.
All siding was in excellent condition at the end of the exposure. Their finding
did, however, strongly suggest that overhangs provide additional protection
for wooden window trims. Current research is investigating other factors
that may contribute to siding problems. Researchers are looking for a correlation
between various measured siding properties and performance. For this research,
siding was placed on test fences, sprayed with water, and periodically inspected
for decay, edge swell, and paint condition. The results of this research
should contribute to better industry quality standards and fewer siding failures.
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Pest Risk Assessments of Importing Raw Logs
In the past, the careless transport of unprocessed forest products has introduced
devastating exotic fungi and insects into the United States. Ophistoma ulmi,
the fungi that causes Dutch elm disease, reached the United States on raw
logs in the early 1900s. Both Cronartium ribicola, the causal agent of white
pine blister rust, and Cryphonectria parasitica, which causes chestnut blight,
are familiar examples of introduced fungi that arrived on nursery stock.
Insects such as the gypsy moth, Asian gypsy moth, and the recently discovered
Asian longhorn beetle were also introduced into the United States. The disastrous
results of these pest introductions demonstrate the need for caution in importing
unprocessed forest products. FPL researchers are helping to meet this need
by participating in pest risk assessments, along with other Forest Service
researchers. These assessments analyze the potential an untreated forest
product has for pest infestation as well as the likely impact such an introduction
would have. Pest risk assessments have been published for logs and chips
of radiata pine, Laurelia and Nothofagus from Chile, Pinus and Abies species
from Mexico, and Eucalyptus species from throughout the eucalyptus-growing
areas of South America. A future assessment will look at all wood used as
packing material and dunnage from throughout the world. This assessment will
address the problem of the Asian longhorn beetle as well as other pests.
An assessment of Australian Eucalyptus will soon be published. The assessments
will be used to develop mitigation measures aimed at preventing further introduction
of exotic pests. Further research will look at how the behavior of introduced
fungi varies in different environments and will evaluate exactly how many
invasive species are in the United States.
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