Treesearch

The mechanisms by which chemical modifications, specifically acetylation, improve the decay resistance of wood are a topic of active research. In the early stages of decay, fungi secrete lowmolecular- weight oxidants or oxidant precursors. These oxidants diffuse through the wet wood cell wall and oxidize cell wall polymers, which enable the decay process to proceed. One hypothesis states that acetylation stops decay by dramatically inhibiting the diffusion of these oxidants through the cell wall (Zeiinka et. al. 2016). Data showing a drastic difference in Fe uptake from solution between...

The use of timber–concrete composite (TCC) bridges in the United States dates back to circa 1925. Two different TCC systems were constructed during this early period. The first system included a longitudinal nail-laminated deck composite with a concrete deck top layer. The second system included sawn timber stringers supporting a concrete deck top layer. Records indicate that most of the TCC highway bridges were constructed between 1930 and 1960. The current U.S. National Bridge Inventory (NBI) database indicates that there may be well over 1,000 of this bridge type still in service. This...

As engineers begin to utilize life-cycle-cost design approaches for timber bridges, there is a necessity for more reliable data about their durability and expected service life. This paper summarizes a comprehensive effort to assess the current condition of more than one hundred timber highway bridge superstructures throughout the United States. This national study was jointly administered by the Forest Products Laboratory and the Federal Highway Administration and relied on data from the National Bridge Inventory database. In-depth inspections were conducted using visual and non-destructiv...

Nanoscale, single-asperity wear of single-crystal silicon carbide (sc- SiC) and nanocrystalline silicon carbide (nc-SiC) is investigated using single-crystal diamond nanoindenter tips and nanocrystalline diamond atomic force microscopy (AFM) tips under dry conditions, and the wear behavior is compared to that of single-crystal silicon with both thin and thick native oxide layers. We discovered a transition in the relative wear resistance of the SiC samples compared to that of Si as a function of contact size. With larger nanoindenter tips (tip radius ≈ 370 nm), the wear resistances of both...

Measuring progress toward sustainability goals is a multifaceted task. International, regional, and national organizations and agencies seek to promote resilience and capacity for adaptation at local levels. However, their measurement systems may be poorly aligned with local contexts, cultures, and needs. Understanding how to build effective, culturally grounded measurement systems is a fundamental step toward supporting adaptive management and resilience in the face of environmental, social, and economic change. To identify patterns and inform future efforts, we review seven case studies...

Endoxylanases classified into glycoside hydrolase family 30 subfamily 8 (GH30-8) have been shown to hydrolyze glucuronoxylan with dependence upon the glucuronic acid (GlcA) appendage. In a recent report, the GH30-8 xylanase from Clostridium thermocellum (CtXyn30A) was shown to hydrolyze arabinoxylan which contains no GlcA. Protein structure comparison with the originally characterized GH30-8 enzymes from Bacillus subtilis and Erwinia chrysanthemi provided no insight to hypothesize why the function of CtXyn30A is unique. In this report, we show that CtXyn30A is a GlcA dependent endoxylanase...

Recent USDA policies, such as the Building Blocks for Climate Smart Agriculture and Forestry, aim to sequester and mitigate greenhouse gases in the forestry and agriculture sectors in the United States. To make informed decisions, the USDA will need to evaluate the carbon benefits of various potential policies. In this paper, we use detailed forest inventory data to project the carbon impacts of a range of modeled policies through 2060: 1) a policy resulting in reduced deforestation due to development, 2) a policy combining a Conservation Reserve Program (CRP) afforestation policy targeting...

In terms of adult tree mortality, harvesting is the most prevalent disturbance in northeastern United States forests. Previous studies have demonstrated that stand structure and tree species composition are important predictors of harvest. We extend this work to investigate how social factors further influence harvest regimes. By coupling the Forest Inventory and Analysis database to U.S. Census and National Woodland Owner Survey (NWOS) data, we quantify social and biophysical variation in the frequency and intensity of harvesting throughout a 20-state region in the northeastern United...

We propose the new species and new combination, Tylopilus aquarius var. aquarius, by elevating T. potamogeton v. aquarius to species level. We also describe a new variety, T. aquarius var. megistus, from the Atlantic Forest states Paraiba and Rio Grande do Norte, Brazil, that produces larger, robust basidiomata and smaller basidiospores as compared to T. aquarius var. aquarius.

Adults and juveniles of some forest breeding birds shift habitat use during the post breeding season from late to early successional forest. Juveniles of smaller passerine species are difficult to radio-track, and there is limited information on their habitat preferences, especially once they become older and independent. We determined if independent hatch-year birds captured in early-successional habitat remained there for extended periods, or if these habitats were only occupied infrequently during foraging activities. We determined habitat use for Ovenbirds (Seiurus aurocapilla),...