Treesearch

Stable isotope compositions of mercury (Hg) were measured in the outlet stream and in soil cores at different landscape positions in a 9.7-ha boreal upland-peatland catchment. An acidic permanganate/persulfate digestion procedure was validated for water samples with high dissolved organic matter (DOM) concentrations through Hg spike addition analysis. We report a relatively large variation in mass-dependent fractionation (δ202Hg; from −2.12 to −1.32‰) and a smaller, but significant, variation of mass-independent fractionation (Δ199Hg; from −0.35 to −0.12‰) during two years of sampling with...

Increases in area burned and fire size have been reported across a wide range of forest and shrubland types in the Western United States in recent decades, but little is known about potential changes in fire regimes of piñon and juniper land cover types. We evaluated spatio-temporal patterns of fire in piñon and juniper land cover types from the National Gap Analysis Program using Monitoring Trends in Burn Severity (MTBS 2016) data (1984 through 2013) for Northern and Southern Intermountain and Central and Southern Rocky Mountain geographic regions. We examined differences in total area...

Provides current information on lumber and plywood production and prices; employment in the forest industries; international trade in logs, lumber, and plywood; volume and average prices of stumpage sold by public agencies; and other related items. Current data and downloadable Excel files are available online.

Cropping system diversity can help build greater agroecosystem resilience by suppressing insect, weed, and disease pressures while also mitigating effects of extreme and more variable weather. Despite the potential benefits of cropping systems diversity, few farmers in the US Corn Belt use diverse rotations. This study examines factors that may influence farmers’ decisions to use more diversified crop rotations in the US Corn Belt through a parallel convergent mixed methods approach, using a multi-level analysis of Corn Belt farmer survey data (n = 4,778) and in-depth interviews (n = 159)....

Information on the distribution of multiple species in a common landscape is fundamental to effective conservation and management. However, distribution data are expensive to obtain and often limited to high-profile species in a system. A recently developed technique, environmental DNA (eDNA) sampling, has been shown to be more sensitive than traditional detection methods for many aquatic species. A second and perhaps underappreciated benefit of eDNA sampling is that a sample originally collected to determine the presence of one species can be re-analyzed to detect additional taxa without...

Forest mycorrhizal type mediates nutrient dynamics, which in turn can influence forest community structure and processes. Using forest inventory data, we explored how dominant forest tree myc- orrhizal type affects understory plant invasions with consideration of forest structure and soil properties. We found that arbuscular mycorrhizal (AM) dominant forests, which are characterised by thin forest floors and low soil C : N ratio, were invaded to a greater extent by non-native inva- sive species than ectomycorrhizal (ECM) dominant forests. Understory native species cover and richness had no...

New residential construction is a primary user of wood products in the United States; therefore, wood products projections require understanding the determinants of housing starts. We model quarterly US total, single-family, and multifamily housing starts with several model specifications, using data from 1979 to 2008, and evaluate their fit out of sample, 2009 –14. Goodness-of-fit statistics show that parsimonious models outperform general models in out-of-sample predictions. Monte Carlo simulations of total housing starts to 2070 project median starts ranging from 0.86 million/year at 0%...

The potential for a tree to reach a great size and to live a long life frequently captures the public's imagination. Sometimes the desire to know the age of an impressively large tree is simple curiosity. For others, the date-of-tree establishment can make a big diff erence for management, particularly for trees at historic sites or those mentioned in property deeds, literature or historical documents. If we know with certainty that a tree is 150 years old, we can be sure that the shade of that tree didn't inspire a poet or revolutionary from 200 years ago. We know that trees tend to...

Prior research has shown that the physical characteristics of one's environment have wide ranging effects on affect and cognition. Other research has demonstrated that one's thoughts have impacts on mood and behavior, and in this three-part research program we investigated how physical features of the environment can alter thought content. In one study, we analyzed thousands of journal entries written by park visitors to examine how low-level and semantic visual features of the parks correlate with different thought topics. In a second study, we validated our ecological results by conductin...

Worldwide, forest plants and fungi that are harvested for their nontimber products are critical for the health of the ecosystems and the well-being of people who benefit from the harvest. This document provides an analysis of the volumes and values of nontimber forest products in the United States. It presents estimates of the annual harvest for a number of product categories over five regions for the United States. Data for the analysis comes from records of harvest permits and contracts issued by the U.S. National Forests and Bureau of Land Management, other Federal agencies, as well as...