Treesearch

We developed ecologically based climate‐fire projections for the western United States. Using a finer ecological classification and fire‐relevant climate predictors, we created statistical models linking climate and wildfire area burned for ecosections, which are geographic delineations based on biophysical variables. The results indicate a gradient from purely fuel‐limited (antecedent positive water balance anomalies or negative energy balance anomalies) to purely flammability‐limited (negative water balance anomalies or positive energy balance anomalies) fire regimes across ecosections....

Birds found outside their typical range, or vagrants, have fascinated naturalists for decades. Despite broad interest in vagrancy, few attempts have been made to statistically examine the explanatory variables potentially responsible for the phenomenon. In this study, we used multiple linear regression to model the occurrence of 28 rare warbler species (family Parulidae) in autumn in northern California and southern Oregon as a function of migration distance, continental population size, distance, and bearing to both closest breeding population and breeding population center. In addition...

The Haines Index is intended to provide information on how midtropospheric conditions could lead to large or erratic wildfires. Only a few studies have evaluated its performance and those are primarily single fire studies. This study looks at 47 fires that burned in the United States from 2004 to 2017, with sizes from 9000 ha up to 218,000 ha based on daily fire management reports. Using the 0-h analysis of the North American Model (NAM) 12 km grid, it examines the performance of the start-day Haines Index, as Haines (1988) originally discussed. It then examines performance of daily Haines...

Many fire-maintained savannas and woodlands are suffering the effects offire exclusion and the concomitant invasion of fire-sensitive trees. In the Pacific West, woodlands dominated by either Oregon white oak (Quercus garryana) or California black oak (Quercus kelloggii) have transitioned from oak-dominated to conifer-dominated (primarily by the native Douglas-fir; Pseudotsuga menziesii) forest conditions with corresponding losses of plant and animal biodiversity. In spite of the prevalence of this transition, few studies have documented these temporal shifts and the consequences for oak...

Fuel-reduction treatments have been used effectively in dry, fire-adapted forests to reduce risk of high-severity crown fire, but it is less certain whether they achieve ecological objectives such as promoting understory diversity. Using long-term data from a fuel-reduction experiment, we tested how conclusions about treatment effectiveness are related to the spatial and temporal scales over which ecological responses are evaluated. We modeled the richness of herbs and shrubs at smaller (1–50m2) and larger (1000m2) spatial scales as functions of pre-treatment richness, thinning intensity,...

Common practices for invasive species control and management include physical, chemical, and biological approaches. The first two approaches have clear limitations and may lead to unintended (negative) consequences, unless carefully planned and implemented. For example, physical removal rarely completely eradicates the targeted invasive species and can cause disturbances that facilitate new invasions by nonnative species from nearby habitats. Chemical treatments can harm native, and especially rare, species through unanticipated side effects. Biological methods may be classified as...

Regional scale maps of homogeneous forest stands are valued by forest managers and are of interest for landscape and ecological modelling. Research focused on stand delineation has substantially increased in the last decade thanks to the development of Geographic Object Based Image Analysis (GEOBIA). Nevertheless, studies focused on even-age dominated forests are still few and the proposed approaches are often heuristic, local, or lacking objective evaluation protocols. In this study, we present a two-stage evaluation strategy combining both unsupervised and supervised evaluation methods...

Rocky Mountain red foxes Vulpes vulpes macroura potentially encounter other red fox Vulpes vulpes lineages at lower elevations, which may include nonindigenous red foxes derived from fur farms. Introgression from nonindigenous red foxes could have negative evolutionary consequences for the rare Rocky Mountain red fox subspecies. Red foxes at high elevations in the Greater Yellowstone Ecosystem exhibit lighter coat colors than those at lower elevations, potentially indicating that they represent the indigenous subspecies and that gene flow across the elevational gradient is restricted. We...

Despite advances in restoration of degraded lands around the world, native plants are still underutilized. Selection of appropriate plant materials is a critical factor in determining plant establishment and persistence. To better inform decision-making, we examined cold-hardiness dynamics, flowering phenology, and survival among five geographically distinct sulfur-flower buckwheat (Polygonaceae: Eriogonum umbellatum Torr.) populations in a common garden. LT50 (a measure of freezing injury) was determined every 6 weeks across a complete year; one population was also evaluated at the...

We developed and applied a wildfire simulation package in the Envision agent-based landscape modelling system. The wildfire package combines statistical modelling of fire occurrence with a high-resolution, mechanistic wildfire spread model that can capture fine scale effects of fire feedbacks and fuel management, and replicate restoration strategies at scales that are meaningful to forest managers. We applied the model to a landscape covering 1.2 million ha of fire prone area in central Oregon, USA where wildland fires are increasingly impacting conservation, amenity values and developed...