Treesearch

Within-grade variability in mechanical properties for visually graded lumber has led to increased deployment of nondestructive testing (NDT) methods, even though the relationships between static bending and NDT-predicted values are often highly variable. Dynamic modulus of elasticity (MOEdyn) was measured using two acoustic velocity instruments and one transverse vibration instrument, along with specific gravity, for 819 pieces of visually graded loblolly pine lumber. Static modulus of elasticity (MOE) and bending strength (Fb) were measured via destructive testing. The probability of...

Juvenile wood (core wood) in softwood species is typically characterized as being less dimensionally stable and having lower mechanical properties than mature wood. Determining the age of transition between juvenile wood and mature wood is important when making judgments about utilization options for naturally occurring stands of trees in the intermountain west region of the United States. Lodgepole pine (Pinus contorta Dougl. ex. Loud.) trees were harvested from four different sites in the US Inland Northwest to include site variations that affect growth, such as elevation, precipitation,...

Studying the effects of drought on forest ecosystems is important in developing a better understanding of forest phenology and productivity. Many previous studies were based on single drought events, whereas effects of recurrent droughts have not been yet fully investigated. This study jointly analyzed the spatial–temporal change of drought patterns with forest phenology and productivity between 2000–2015 in the western Central Hardwood Forests at Missouri, Arkansas, Illinois, Oklahoma, and Kansas of the US. Characteristics of forest phenology and productivity were captured by utilizing...

Heartwood extract from white mulberry (Morus alba L.) (Rosales: Moraceae) were investigated for antitermitic activity against Reticulitermes favipes (Kollar) (Blattodea: Rhinotermitidae) in laboratory experiments. An ethanol:toluene (2:1) solvent system was used to remove extract from heartwood shavings. A concentration-dependent feeding response and mortality were observed for termites exposed to a concentration series range of 1.25 to 10 mg/ml of extract based on their dry weight. Results showed that maximum termite mortality occurred at 10 mg/ml. Based on the concentration series data,...

A prediction that has gained considerable traction in the American pika (Ochotona princeps) literature is that because of climate change, high mortality is likely to occur in winters of low or early snowmelt and cause extirpation of local populations. The basis for this prediction is the perception that the absence of an insulative layer of snow to protect pikas from severe winter cold temperatures may cause animals to utilize metabolic reserves through excessive thermoregulation before the spring emergence of fresh vegetation, or die directly from exposure to extreme winter temperatures....

Millions of people head to federal lands every year for recreation—891 million visits in 2016 alone. These visits have significant economic implications, not only for restaurants, resorts, outfitters, and other businesses near recreation sites, but also for the people actually participating in outdoor recreation.Scientists Eric White and Jeff Kline, both with the U.S. Forest Service Pacific Northwest Research Station, worked with colleagues to summarize results from more than 400 studies that measure the economic value that people hold for recreation opportunities. The information shows...

The non-native invasive tree, Ailanthus altissima is an increasing threat to the diversity and health of temperate forests. Female trees are prolific producers of wind-dispersed seeds. It is not known if Ailanthus seeds remain viable in natural growing conditions beyond two years. We collected Ailanthus seeds from eleven sources in fall 2010 and incubated outdoors in either mixed oak leaf litter or mineral soil (10 cm depth) for five years to assess seed viability. Each May sets of seeds were retrieved, counted and sown in a greenhouse to measure germination. Initially germination rates...

We analyzed variations in three tree properties: tissue density, carbon fraction, and carbon density within bole tissues of nine Californian conifer species. Model performance for all three tree properties was significantly improved with the addition of covariates related to crown characteristics and position within the tree. This suggests that biomass and carbon mass estimates that rely on fixed wood density and carbon fraction may be inaccurate across tree sizes. We found a significant negative relationship between tissue density and carbon fraction within tree bole tissues, indicating...

IMPORTANCE: Neighborhood physical conditions have been associated with mental illness and may partially explain persistent socioeconomic disparities in the prevalence of poor mental health. OBJECTIVE: To evaluate whether interventions to green vacant urban land can improve selfreported mental health. DESIGN, SETTING, AND PARTICIPANTS: This citywide cluster randomized trial examined 442 community-dwelling sampled adults living in Philadelphia, Pennsylvania, within 110 vacant lot clusters randomly assigned to 3 study groups. Participants were followed up for 18 months preintervention and...

The Forest Service, U.S. Department of Agriculture, defines success in the wildland fire response environment as ìsafely achieving reasonable objectives with the least firefighter exposure necessary while enhancing stakeholder support for our management effortsî. However, persistent information and knowledge gaps challenge the agencyís ability to measure success in coming fire seasons. In this paper, we outline a roadmap to help fill these gaps, describing progress towards developing meaningful fire response key performance indicators (KPIs). We focus on characterizing suppression resource...