Treesearch

Interactions between climate and ecosystem properties that control phenological responses to climate warming and drought are poorly understood. To determine contributions from these interactions, we used space-borne remotely sensed vegetation indices to monitor leaf development across climate gradients and ecoregions in the southeastern United States. We quantified how air temperature, drought severity, and canopy thermal stress contribute to changes in leaf flushing from mountainous to coastal plain regions by developing a hierarchical state-space Bayesian model. We synthesized daily...

Natural resources across the United States are increasingly managed at the landscape scale through cooperation among multiple organizations and landowners. United States Department of Agriculture Forest Service (USFS) agency leaders have widely promoted this approach since 2009 when Secretary of Agriculture Vilsack called for "all lands" management. Landscape scale projects have been undertaken to address multiple goals such as single species conservation, resilience to fire, invasive species eradication, and others. The West Virginia Restoration Venture (WVRV)—one of five landscape scale...

Local point measurements of fire dynamics in field-scale experiments of wildland fires are highly useful. This is true both for understanding the mechanisms driving fire spread that result in the observed macroscopic behaviors, but also in terms of providing comparison points for numerical tools, such as detailed physics-based fire behavior models. This work describes measurements of temperature, velocity, and radiative heat flux that were made in a field-scale fire experiment in a pine forest, with the aim of providing both of the above benefits. Regions of both surface fire and crown...

The stabilization kinetics of polyacrylonitrile-co-methacrylic acid (PAN-co-MAA) and cellulose nanocrystal (CNC) composite films were studied with up to 40 wt% CNC loading using differential scanning calorimetry (DSC). It was determined that the addition of CNC reduced the activation energy of the polyacrylonitrile cyclization reaction by 16% irrespective of the CNC loading in the range of 5e40 wt%. There was also a development of a new exothermic peak in the PAN-co-MAA/CNC composite films after cyclization not seen in the neat PAN-co-MAA and neat CNC samples, indicating a different set of...

This study focused on the penetration of adhesive into cell lumens and cell walls. Douglas-fir samples containing an iodinated phenol-formaldehyde adhesive were analyzed using nano-X-ray computed tomography (XCT), X-ray fluorescence microscopy, and energy-dispersive X-ray spectroscopy to observe adhesive penetration in cell walls. A gradient of penetration was observed within the cell wall structure. In addition, these nano-XCT datasets were indexed to previous micro-XCT datasets, which gave the ability to link the nanoscale cell wall penetration to microscale penetration in to the porous...

Elastomeric sealants are vital to the construction of energy efficient and water tight buildings. Sealants are a small fraction of the construction budget. Upon failure their removal and reinstallation, and repair of moisture/mold damage can run in to the 10’s of millions with the added risk of illness based litigation. In this research program we are seeking to discern the significance of environmental and strain effects on sealant durability as well as the initial state of stress (aka installation/cure conditions). Sealant bonded specimens are fixtured on automated test instruments and...

Cellulose nanocrystals (CNCs) can be attractive templates for the generation of functional inorganic/organic nanoparticles, given their fine sizes, aspect ratios, and sustainable worldwide availability in abundant quantities. Here, we present for the first time a scalable, surfactant-free, tailorable wet chemical process for converting commercially available CNCs into individual aspected gold nanoshell-bearing particles with tunable surface plasmon resonance bands. Using a rational cellulose functionalization approach, stable suspensions of positively charged CNCs have been generated....

Estimating marten (Martes spp.) survival rates in managed forests is important for comparisons with vital rates in unmanaged forests, and data across populations in different forest types are needed in meta-analyses. We estimated survival rates of a Pacific Marten (Martes caurina) population from 1993 to 1998. This population experienced no fur trapping and occurred in an atypical habitat of sparse tree-canopy cover, small tree diameters, and many natural openings and logging clearcuts. In the beetle-damaged, salvage-logged Lodgepole Pine (Pinus contorta) forest, downed wood and snags were...

The Cascade red fox (CRF) occurred historically throughout subalpine and alpine habitats in the Cascade Range of Washington and southernmost British Columbia, but now appears to be extremely rare. Causes for its apparent decline are unknown, as is the current distribution and connectivity of its populations. Additionally, the introduction of nonnative (fur-farm) red foxes to surrounding lowland areas during the past century raises concerns about their expansion to higher elevations and potential hybridization with the CRF. We conducted noninvasive genetic sampling and analyses of CRFs in a...

A new family of materials comprised of cellulose, cellulose nanomaterials (CNMs), having properties and functionalities distinct from molecular cellulose and wood pulp, is being developed for applications that were once thought impossible for cellulosic materials. Commercialization, paralleled by research in this field, is fueled by the unique combination of characteristics, such as high on-axis stiffness, sustainability, scalability, and mechanical reinforcement of a wide variety of materials, leading to their utility across a broad spectrum of highperformance material applications....