Treesearch

These guidelines are designed for decision makers (selectmen, county commissioners, city planners, preservation officers, etc.) that have responsibility for repairing and maintaining existing covered bridges to help them understand what goes into making effective decisions about how, and when, to repair a covered bridge. The purpose of these guidelines is to present the steps necessary for decision makers to identify effective rehabilitation techniques for restoring the structural integrity of covered bridge members. The intent is to retain the maximum amount of historic fabric while...

Background and Aims Wood is a major innovation of land plants, and is usually a central component of the body plan for two major plant habits: shrubs and trees. Wood anatomical syndromes vary between shrubs and trees, but no prior work has explicitly evaluated the contingent evolution of wood anatomical diversity in the context of these plant habits. Methods Phylogenetic comparative methods were used to test for contingent evolution of habit, habitat and wood anatomy in the mega-diverse genus Croton (Euphorbiaceae), across the largest and most complete molecular phylogeny of the genus to...

The 20th International Nondestructive Testing and Evaluation of Wood Symposium was hosted by the USDA Forest Service Forest Products Laboratory in Madison, Wisconsin, USA, on September 12–15, 2017. This Symposium was a forum for those involved in nondestructive testing and evaluation (NDT/NDE) of wood and brought together many NDT/NDE users, suppliers, international researchers, representatives from various government agencies, and other groups to share research results, products, and technology for evaluating a wide range of wood products, including standing trees, logs, lumber, and wood...

The mechanisms governing the ability of water-soluble polymers (WSP) to alter the rheological properties of lignocellulosic biomass to achieve processing advantages are investigated. Lignocellulosic fiber surface chemistry is found to be an important factor in the efficacy of WSPs as rheological modifiers, and a strong correlation between the amount of adsorbed polymer at fiber surfaces and the yield stress of the fiber suspension indicate that adsorption of polymer is important for rheological modification. Three fiber suspensions of varying physical chemistry were produced from Aspen...

The effect of landfill exposure on residual levels of cellulose, hemicellulose, and lignin was investigated on wood materials removed from differing depths in a 5-yr-old landfill cell in western Oregon. There was little evidence of change in the levels of these components with increasing landfill cell depth in softwood lumber, softwood plywood, or hardwood lumber. The results confirm studies at other landfills showing that wood degradation rates under anaerobic conditions in landfills are much slower than predicted and that models to predict these rates need to be modified.

The fungal pathogen Heterobasidion irregulare has caused substantial damage to pine species in much of the south-eastern United States, but the potential for damage from Heterobasidion root disease to forest tree species of the Great Lakes Region has not been thoroughly investigated. In each of three trials in two infested stands, fresh stem discs of six native conifer species were exposed to natural inoculum and examined for the asexual Spiniger stage of H. irregulare after incubation in the laboratory. In the first trial, the fungus was infrequently observed on discs, and differences...

Wood-based products can be a sustainable and more environmentally friendly alternative to traditional construction materials because of their reduced contribution to air and water pollution. An integral component of these products is often an adhesive. Because wood is hygroscopic, moisture-induced swelling in the cell walls near the wood–adhesive bond lines can lead to durability and performance issues. Unfortunately, researchers working toward improving the moisture durability of forest products are hindered by an incomplete understanding of the nanoscale mechanisms that contribute to...

With global urbanization trends, the demands for tall residential and mixed-use buildings in the range of 8~20 stories are increasing. One new structural system in this height range are tall wood buildings which have been built in select locations around the world using a relatively new heavy timber structural material known as cross laminated timber (CLT). With its relatively light weight, there is consensus amongst the global wood seismic research and practitioner community that tall wood buildings have a substantial potential to become a key solution to building future seismically...

The research reported here focuses on the use of time and frequency domain analysis techniques for assessing the internal condition of timbers. Several large timbers obtained from a historic public viewing tower were evaluated with acoustic-based nondestructive testing techniques. Waveforms were captured and analyzed using both time and frequency domain techniques. The slope of the phase with respect to frequency shows potential to be a metric that is more sensitive to the presence of internal decay than time of flight.

Currently, various chemical-mechanical treatments were widely used in biofuel production to achieve high total sugar yields. However, the interaction between two treatments was scarcely investigated. In this study, we employed a ball milling process to create ultrastructural changes for Douglas-fir (Pseudotsuga menziesii) micronized wood powders. The 0, 30, and 60 min ball milled wood powders resulted in a crystallinity index of 0.41, 0.21, and 0.10 respectively. It was found that the ultrastructural changes accelerate monomeric sugars production without influencing the yield of sugar...