Treesearch

Wood-inhabiting macrofungi inhabit substrata that differ in size, state of decay, and moisture content. Thus, the ecologies of fungi growing on wood differ. Wood-inhabiting species include fungi that were in or on the wood when a tree or tree part fell to the ground (e.g., pathogens and nonpathogenic endophytes of living tissue, heart rots), as well as the succession of fungi that follow in an organized fashion as the wood deteriorates. In addition, many putative and known ectomycorrhizal species “climb up” on wood to fruit and simultaneously may obtain nutrients from the wood by degrading...

In contrast to DNA, messenger RNA (mRNA) in complex substrata is rarely analyzed, in large part because labile RNA molecules are difficult to purify. Nucleic acid extractions from fungi that colonize soil are particularly difficult and plagued by humic substances that interfere with Taq polymerase (Tebbe and Vahjen 1993 and references therein). Magnetic capture techniques have overcome these problems, allowing rapid and efficient purification of microbial DNA and RNA. Magnetic capture involves the use of magnetic beads that are covalently attached to single-stranded DNA, most commonly...

Concerns about indoor air quality due to mold growth have increased dramatically in the United States. In the absence of proper moisture management, fungicides need to be developed for indoor use to control mold establishment. An ideal fungicide for prevention of indoor mold growth on wood-based materials needs to specifically prevent spore germination and provide long-term protection under conditions of high humidity. Fungicides intended for indoor use must be nontoxic, nonvolatile, odorless, and hypoallergenic. Multicomponent systems were tested in AWPA soil block tests for inhibition of...

Environmental pressures to eliminate arsenate from wood preservatives has resulted in voluntary removal of CCA for residential applications in the United States. A new generation of copper organic preservatives has been formulated to replace CCA for decking and in-ground applications but there is no guarantee that these preservatives represent a permanent solution to all related problems. Therefore, it is still necessary to evaluate alternative treatments, as well as naturally durable wood species, in order to be prepared for future changes in the field. In this study, six hardwoods and...

For decades chromated copper arsenate (CCA) was the primary preservative for treated wood used in residential construction. However, recent label changes submitted by CCA registrants will withdraw CCA from most residential applications. This action has increased interest in arsenic free preservative systems that have been standardized by the American Wood Preservers' Association. These include acid copper chromate (ACC), alkaline copper quat (ACQ), copper azole (CBA-A and CA-B), copper citrate (CC), copper dimethyldithio-carbamate (CDDC), and copper HDO (CX-A). All of these CCA alternatives...

This paper discusses results of tests conducted to expand the data base on the performance of timber rivet connections in U.S. domestic species to verify existing and proposed design procedures. Eight-, 80-, and 200-rivet connections were tested. The 8-rivet joint tests illustrate the effects of material type, rivet length, and load direction on the behavior of rivet connections when gross wood failures are avoided. The 80-rivet connections, loaded perpendicular to grain, show the effect of rivet spacing as well as test support conditions on failure mode and strength. The 200-rivet joints,...

Preservative-treated wood contains components that may be toxic to non-target organisms if released into the environment in sufficient quantities. Numerous studies have been conducted to determine the rate of preservative release from treated wood and/or the extent of their subsequent accumulation in the environment. These studies have produced a wide range of results, with a corresponding range of interpretations and recommendations. This paper reviews research on wood preservative leaching and environmental accumulation and discusses sources of the variability in research findings....

To keep pace with customer demands while phasing out old and unserviceable test equipment, the staff of the Engineering Mechanics Laboratory (EML) at the USDA Forest Service, Forest Products Laboratory, designed and assembled a hydraulic bending test machine. The EML built this machine to test dimension lumber, nominal 2 in. thick and up to 12 in. deep, at spans up to 20 ft and loads up to 20,000 lbf. The hydraulic bending test machine was built using parts of a 100,000-lbf compression test frame. Added components included W12 by 65 steel beams; steel tube sections, L sections, and...

This report provides general and statistical information on forests products markets in terms of production, trade, consumption, and prices. The state of the United States economy is described as of the second quarter of 2003. Market developments are described for timber products, paper and paperboard, fuelwood, and forest products prices. Policy initiatives that address domestic markets and international trade concerns related to U.S. forest products are also discussed. Detailed information and projections are presented for the year 2004.

Occasionally, creosote-treated railroad ties need to be replaced, sometimes in sensitive environments such as wetlands. To help determine if this is detrimental to the surrounding environment, more information is needed on the extent and pattern of creosote, or more specifically polycyclic aromatic hydrocarbon (PAH), migration from railroad ties and what effects this would have on the surrounding environment. This study is a report on PAH level testing done in a simulated wetland mesocosm. Both newly treated and weathered creosote-treated railroad ties were placed in the simulated wetland....