Treesearch

To develop high-performance wood materials, a novel preparation strategy is presented in this study. Wood fiber mats impregnated with phenolic resin, were laminated into a densified material. Wood lumens collapsed layer by layer during densification, leading to a compact multi-layered structure. The densified material had excellent mechanical properties and favorable water resistance. The flexural, compressive, and short-beam shearing strength were approximately 230%, 400%, and 260% higher than that of natural wood, respectively. The water absorption rate and thickness swelling rate in...

Recent experimental work has revealed that the hydroxystilbene piceatannol can function as a monomeric unit in the lignification of palm fruit endocarp tissues. Results indicated that piceatannol homo-couples and crosscouples with monolignols through radical reactions and is integrally incorporated into the lignin polymer. The current work reports on the thermodynamics of the proposed reactions using density functional theory calculations. The results indicated that, in general, the energetics of both homo-coupling and cross-coupling are not dissimilar from those of the monolignol coupling,...

New C2-symmetric and C2-asymmetric Co-Schiff base catalysts tethered to arylpiperazine units were synthesized and used to oxidize phenolic lignin models to para-benzoquinones. Synthetic approaches to these catalysts were optimized to include fewer steps and broaden the types of catalyst structures available. In contrast to conventional Co-Schiff base catalysts, these systems induce phenolic oxidation in the absence of an external axial base, simplifying the process. Asymmetric catalysts bearing a phenylethylene or diphenylmethyl piperazine substituent display the highest catalytic activity...

The Mount St. Helens eruption on May 18, 1980, fundamentally transformed the surrounding landscape. The eruption triggered geophysical processes that are still unfolding. A debris avalanche caused by the eruption, for example, blocked the outlet from Spirit Lake. To prevent the rising lake level from breaching the blockage and potentially flooding communities downstream, the U.S. Army Corps of Engineers built an outlet tunnel to maintain safe lake levels. However, the tunnel must be periodically closed for repairs, during which time the lake can rise precariously high.In 2015, the Gifford...

Wildland fire has always been an important ecosystem process across the sagebrush biome. Recently, the scale of sagebrush ecosystem loss and fragmentation has increased due to a combination of uncharacteristic wildland fire, invasive annual grasses, juniper (Juniperus spp.) and piñon (Pinus spp.) expansion, and anthropogenic land use and development. A strategic approach to wildland fire and vegetation management is now required that focuses available resources in the places that will maximize conservation return on investment. Wildland fire management integrated with vegetation management...

One of the most significant stressors to the sagebrush biome is expansion and dominance of nonnative ecosystem-transforming species, particularly invasive annual and perennial plants. Presidential Executive Orders 13112 and 13751 define an invasive species as "a non-native organism whose introduction causes or is likely to cause economic or environmental harm, or harm to human, animal, or plant health." The use of the term "invasive species" requires two basic criteria to be met: (1) the species is alien, nonnative, or exotic to the ecosystem in question; and (2) the species has been...

Native plant species are the foundation of sagebrush ecosystems and provide essential habitat for wildlife species, such as Greater sage-grouse (Centrocercus urophasianus; hereafter, GRSG). The National Seed Strategy for Rehabilitation and Restoration (hereafter, Seed Strategy) (PCA 2015) strives to provide all land managers - Federal, tribal, State, county, private, and nongovernmental organization - the tools they need to address ecological restoration across the United States. The Seed Strategy provides a coordinated approach to improving the use of native seed, building Federal and...

Part 1 of the Science Framework identifies livestock grazing as the most widespread land use in the sagebrush biome (Chambers et al. 2017a; hereafter, Part 1). In the Conservation Objectives Team Report (USDOI FWS 2013) improper livestock grazing is considered a present and widespread threat to Greater sage-grouse (Centrocercus urophasianus; hereafter, GRSG) for most GRSG populations. Livestock grazing affects the composition and structure of plant communities across the sagebrush biome and, consequently, the habitats of GRSG, other species at risk, and high value resources (Boyd et al....

Wild horses (Equus caballus) and wild burros (E. asinus), like domestic livestock, can alter sagebrush ecosystem structure and composition and affect habitat quality for sagebrush dependent species (Beever and Aldridge 2011). The presence of Federally protected wild horses and wild burros can also have substantial effects on the capacity for habitat restoration efforts to achieve conservation and restoration goals. In the Conservation Objectives Team Report (USDOI FWS 2013), the presence of wild horses and burros was considered a threat to Greater sage-grouse (Centrocercus urophasianus;...

Managing for sagebrush ecosystems that are resilient to disturbance and resistant to invasive plants often requires managers to make tough decisions in the face of considerable complexity and uncertainty. The decisionmaking environment is often characterized by multiple management objectives, limited management authority and capabilities, dynamic ecosystems and plant communities, and uncertain responses to management actions. Resource decisionmakers must be able to determine appropriate objectives based on desired management outcomes and sort through the different management considerations...