Treesearch

Large wildfires are an increasing threat to the western U.S. In the 2017 fire season, extensive wildfires occurred across the Pacific Northwest (PNW). To evaluate public health impacts of wildfire smoke, we integrated numerical simulations and observations for regional fire events during August-September of 2017. A one-way coupled Weather Research and Forecasting and Community Multiscale Air Quality modeling system was used to simulate fire smoke transport and dispersion. To reduce modeling bias in fine particulate matter (PM2.5) and to optimize smoke exposure estimates, we integrated...

Foresters have long known that trees under stress from fire injury are vulnerable to bark beetle attacks. Rick Kelsey and Doug Westlind, researchers with the Pacific Northwest Research Station, have developed a new mechanistic model to explain how physiological changes cause heat stress in woody tissues exposed to sublethal fire temperatures and produce a chemical signal that attracts some bark beetles.When heat disrupts normal cell functions and energy production, ethanol is synthesized as a short-term survival strategy. If enough ethanol accumulates and is released to the atmosphere...

Effects of intensive forest management on soil phosphorus (P) are unclear and may impact long-term site productivity. We assessed changes in P availability over 10 years associated with harvest intensity (bole-only vs. whole-tree harvest) and vegetation control treatments (initial vegetation control (IVC) vs. five years of annual vegetation control (AVC)) using a P fractionation procedure. Fractions were characterized at 0–15, 15–30, and 30–60 cm soil depths in two coast Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco var. menziesii) plantations with strongly contrasting soil properties...

The Fuel Characteristic Classification System (FCCS) was designed to store and archive wildland fuel characteristics within fuelbeds, defined as the inherent physical characteristics of fuels that contribute to fire behavior and effects. The FCCS represents fuel characteristics in six strata including canopy, shrubs, herbaceous fuels, downed wood, litter-lichen-moss, and ground fuels. Each stratum is further divided into one or more categories and subcategories to represent the complexity of wildland and managed fuels. A variety of techniques to measure and summarize fuelbed data are...

Structure of vegetation significantly influences its flammability and resulting fire spread. Despite considerable amount of laboratory studies, experimental works carried out with full plant specimens, representative of field conditions, are still limited. Present study aims to collect meaningful experimental data on structure and flammability of shrub of rockrose and evaluate the predictions of a fire model (WFDS) against this dataset. Spatial distribution of fuel elements, sorted according to their characteristic thickness, was established from destructive measurements. 28 fire tests...

Coexistence of ecologically similar species can be maintained by partitioning along one or more niche axes. Three-dimensional structural complexity is central to facilitating resource partitioning between many forest species, but is underrepresented in field-based studies. We examined resource selection by sympatric northern spotted owls (Strix occidentalis caurina), a threatened species under the US Endangered Species Act, and nonnative barred owls (S. varia) in western Oregon, USA to explore the relative importance of canopy heterogeneity, vertical complexity of forest, and abiotic...

Effective conservation and management of small mammals require knowledge of the population dynamics of co-occurring species. We estimated the abundances, autocorrelations, and spatiotemporal associations of 4 small-mammal species from 2011–2016 using live-trapping mark-recapture methods on 9 sites across elevation and canopy openness gradients of a late-successional forest in the H. J. Andrews Experimental Forest, on the west slope of the Oregon Cascades. We also quantified species-specific spatial variation in adult sex ratios and body mass. We used Huggins closed capture models to...

With the accumulating evidence of changing disturbance regimes becoming increasingly obvious, there is potential for disturbance ecology to become the most valuable lens through which climate-related disturbance events are interpreted. In this paper, I revisit some of the central themes of disturbance ecology and argue that the knowledge established in the field of disturbance ecology continues to be relevant to ecosystem management, even with rapid changes to disturbance regimes and changing disturbance types in local ecosystems. Disturbance ecology has been tremendously successful over...

To successfully reproduce, conifers must have impeccable timing—opening their female cones to receive pollen from the male cones of nearby trees. This timing is a response to temperature and other environmental cues. It is to the tree’s advantage to flower when risk of damaging frost is low, but early enough in the spring to take full advantage of the growing season.Douglas-fir is ecologically important and the cornerstone of the timber industry in the Pacific Northwest. Seed orchard managers carefully breed different populations of the species to produce seedlings that will thrive in...

Stream habitat restoration in the Entiat River, Washington, has increased juvenile Chinook abundance in pools with engineered logjams (ELJs); however, high spatial, temporal, and inter-species variation complicates distinguishing treatment effects between restored and unrestored habitat. Here we show that the scale of post restoration effectiveness monitoring can also be a confounding factor in such studies. In three stream reaches, we conducted snorkel surveys of (1) spatially randomized untreated habitat in which we also randomized survey area, and (2) restored (ELJ) habitat that...