Treesearch

Recent research suggests that high levels of ambient near-surface atmospheric turbulence are often associated with rapid and sometimes erratic wildland fire spread that may eventually lead to large burn areas. Previous research has also examined the feasibility of using near-surface atmospheric turbulent kinetic energy (TKEs) alone or in combination with the Haines index (HI) as an additional indicator of anomalous atmospheric conditions conducive to erratic or extreme fire behavior. However, the application of TKEs-based indices for operational fire-weather predictions in the United...

A decline in urban forest structure and function in the United States jeopardizes the current focus on developing sustainable cities. A number of social dilemmas—for example, free-rider problems—restrict the sustainable production of ecosystem services and the stock of urban trees from which they flow. However, institutions, or the rules, norms, and strategies that affect human decision-making, resolve many such social dilemmas, and thus, institutional analysis is imperative for understanding urban forest management outcomes. Unfortunately, we find that the definition of institutions...

Nondestructive evaluation of cellulose nanofibril (CNF) films was performed using cantilever beam vibration (CBV) and acoustic methods to measure dynamic modulus. Static modulus was tested using tensile tension method. Correlation analysis shows the data measured by CBV has little linear relationship with static modulus, possessing a correlation coefficient (R2) of 0.282. However, the data tested by acoustic method correlated well with the static modulus, approaching a correlation coefficient of 0.6. Irregular sample shape largely contributed to these obtained results. The dynamic modulus,...

The second glued-laminated structure built in the United States was constructed at the USDA Forest Products Laboratory (FPL) in 1934 to demonstrate the performance of wooden arch buildings. After decades of use the structure was decommissioned in 2010. Shortly after construction, researchers structurally evaluated the glued-laminated arch structure for uniform loading on the center arch. This structural system evaluation was added to the existing laboratory work on glued-laminated arches to develop the foundation on which the current glued-laminated arch design criteria is based. After...

As many engineers begin to implement life cycle cost analyses within the preliminary bridge design phase, there is a significant need for more reliable data on the expected service life of highway bridges. Many claims are being made about the expected longevity of concrete and steel bridges, but few are based on actual performance data. Because engineers are least familiar with timber bridges, their expected longevity is often unfairly estimated at only 25-30 years. A national scale project has been developed for the United States, led by the USDA Forest Products Laboratory and the U.S....

In this study, we examined three individual log measures (acoustic velocity, log diameter, and log vertical position in a tree) for their ability to predict average modulus of elasticity (MOE) and grade yield of structural lumber obtained from Douglas-fir (Pseudotsuga menziesii [Mirb. Franco]) logs. We found that log acoustic velocity only had a moderate correlation with average MOE of the lumber produced from the logs (R2 = 0.40). Log diameter had a weak correlation with average lumber MOE (R2 = 0.12). Log vertical position in a tree was found to have a relatively good relationship with...

Compared with other construction materials, wood products are environmentally attractive because they sequester carbon, are renewable, and are low in embodied energy. Lumber salvaged from building removal possesses these same qualities but with additional environmental attributes. In spite of the environmental attractiveness of reclaimed lumber, its widespread acceptance is hampered because it is not formally recognized in our grading or engineering design standards. This causes confusion for consumers, builders, and building officials, both in the marketplace as well as at the jobsite. In...

Chemical images help understanding of wood properties, durability, and cell wall deconstruction for conversion of lignocellulose to biofuels, nanocellulose and other value added chemicals in forest biorefineries. We describe here a new method for nondestructive chemical imaging of wood and wood-based materials at the micro-scale to complement macro-scale methods based on X-rays, acoustics, and georadar. Chemical detection, mapping and digital image construction were obtained with a high resolution Fourier transformed infrared microspectroscopy facility that obtains infrared light from a...

In this study, we examined stress wave velocity patterns in the cross sections of black cherry trees, developed analytical models of stress wave velocity in sound healthy trees, and then tested the effectiveness of the models as a tool for tree decay diagnosis. Acoustic tomography data of the tree cross sections were collected from 12 black cherry trees at a production forest. Trees were subsequently cut, and the disk at each test location was obtained to assess the true physical condition. Stress wave velocity data of different paths across grain, from radial to tangential, were extracted...

The hydraulic resilience of a species is determined by multiple physiological and structural traits. Understanding how these traits are integrated at the organismal level to yield adequate hydraulic fitness in a given environment would be a fertile area for future research. This type of information is essential for realistic predictions of species hydraulic limits under current and future climate change scenarios.