Treesearch

Una frase que se escucha a menudo, “no hay futuro sin humo”, describe el fuego, y el humo asociado, como un proceso ecológico indisolublemente ligado a los bosques del Oeste. Si bien el fuego puede proporcionar muchos beneficios, como la reducción de combustibles y la renovación de los bosques, el humo de los incendios plantea un grave desafío para la salud pública, los administradores de tierras y los reguladores de la calidad del aire. Entonces, ¿podemos reducir estos desafíos?English version: https://research.fs.usda.gov/treesearch/67647

Urban smoke exposure events from large wildfires have become increasingly common in California and throughout the western United States. The ability to study the impacts of high smoke aerosol exposures from these events on the public is limited by the availability of high-quality, spatially resolved estimates of aerosol concentrations. Methods for assigning aerosol exposure often employ multiple data sets that are time-consuming to create and difficult to reproduce. As these events have gone from occasional to nearly annual in frequency, the need for rapid smoke exposure assessments has...

The importance of crown size in forest management is well recognized, with crown length influencing tree growth and survival. Crown length can serve as a proxy for available photosynthetic area and potential tree growth which makes it an important component of process-based forest models. However, predicting the height to crown base and, hence, crown length, accurately remains challenging due to limited understanding of mechanisms of branch mortality. We conducted an experiment to elucidate the conditions that lead to the death of lower branches under shade conditions in loblolly pine...

The current study assessed the efficacy of heartwood extracts from Tectona grandis, Dalbergia sissoo, Cedrus deodara, and Pinus roxburghii, combined with linseed oil, as protectants for two non-durable wood species against termites and decay fungi. Stakes measuring 45.7 × 1.9 × 1.9 cm and blocks measuring 12.5 × 3.75 × 2.5 cm of the sapwood of southern pine (Pinus sp.) and cottonwood (Populus sp.) were impregnated via vacuum pressure with individual heartwood species extract, linseed oil, or a combination of both. For comparison, solid heartwood stakes and blocks of the wood species used...

Cross laminated timber (CLT) has become a popular wood composite in large building applications that were previously limited to concrete and steel. To extend service and prevent biological attack, chemical protectants are often applied to wood. Cross laminated timber panels are not typically treated, in part due to a lack of data on efficient and effective methods for treating large panels. There are also limited long term field data regarding the exposure of CLT to biological attack. In this study, commercially prepared CLT panels consisting of either 5-ply Norway spruce or 3-ply southern...

The ability of insecticidal soil drenches or spray-on insecticide/fungicide treatments to protect mass timber elements exposed in a high moisture environment but out of direct soil contact was assessed using a modified AWPA ground proximity test established in 2017. Three-ply Douglas-fir CLT pieces measuring 305 x 355 x 105 mm (L x H x W) were installed at the Harrison Experimental Forest (HEF) (Saucier, Mississippi) in 2017. Test samples were placed in sets of two on bricks approximately 150 mm apart, 75 mm above the soil and covered with ventilated waterproof covers. A total of 20 test...

Rates and pathways of secondary succession were investigated and compared between clearcut and surface-mined sites in east Tennessee using chronosequence techniques. Plots were established at 5-year age intervals ranging up to 30 years after the disturbances on sites with similar productivities. Clearcut sites were hypothesized to undergo vegetative succession more rapidly than surface-mined sites due to the difference in intensity and impact of disturbance on the substrate. A control site for each type of disturbance was also evaluated as a metric for the expected pathway of succession,...

Upland forests of east Texas were historically composed of varying mixtures of pine and hardwood species, with local structure and composition driven by site characteristics and fire regimes. The restoration of natural communities, including upland woodlands with mixtures of shortleaf pine (Pinus echinata) and oaks (Quercus spp.), provides conservation benefit, but we lack information on optimal silvicultural practices to meet restoration objectives. We examined contemporary and past stand structure and composition and stand dynamics of a shortleaf pine-post oak woodland at Boggy Slough...

In this study, CLT trailer decking was manufactured to current military trailer decking specifications, verified using PRG320 performance criteria, and treated with either waterborne or oil borne wood preservatives. Preliminary results show adequate uptake of preservative solution and subsequent testing shows minimal effect due to treatment. Field durability tests are also being conducted of treated and untreated materials in tropical sites in Suriname and 8-month data is presented herein. Presence of gaps in the CLT layup have proven problematic as it presents a pocket for collection of...

Premise: Leaf tensile resistance, a leaf's ability to withstand pulling forces, is an important determinant of plant ecological strategies. One potential driver of leaf tensile resistance is growing season length. When growing seasons are long, strong leaves, which often require more time and resources to construct than weak leaves, may be more advantageous than when growing seasons are short. Growing season length and other ecological conditions may also impact the morphological traits that underlie leaf tensile resistance.Methods: To understand variation in leaf tensile resistance, we...