The Fire and Fire Surrogate (FFS) project is a large long-term metastudy established to assess the effectiveness and ecological impacts of burning and fire "surrogates" such as cuttings and mechanical fuel treatments that are used instead of fire, or in combination with fire, to restore dry forests. One of the 13 national FFS sites is the Northeastern Cascades site at Mission Creek on the Okanogan- Wenatchee National Forest. The study area includes 12 forested stands that encompass a representative range of dry forest conditions in the northeastern Cascade Range. We describe site histories and environmental settings, experimental design, field methods, and quantify the pretreatment composition and structure of vegetation, fuels, soils and soil biota, entomology and pathology, birds, and small mammals that occurred during the 2000 and 2001 field seasons. We also describe the implementation of thinning treatments completed during 2003 and spring burning treatments done during 2004 and 2006.

Removing dams that are outdated, unsafe, or pose significant economic or environmental costs has emerged in the last 10 years as a major river restoration strategy.

Timber harvest following wildfire leads to different outcomes depending on the biophysical setting of the forest, pattern of burn severity, operational aspects of tree removal, and other management activities. Fire effects range from relatively minor, in which fire burns through the understory and may kill a few trees, to severe, in which fire kills most trees and removes much of the organic soil layer. Postfire logging adds to these effects by removing standing dead trees (snags) and disturbing the soil. The influence of postfire logging depends on the intensity of the fire, intensity of the logging operation, and management activities such as fuel treatments. In severely burned forest, timing of logging following fire (same season as fire vs. subsequent years) can influence the magnitude of effects on naturally regenerating trees, soils, and commercial wood value. Removal of snags reduces long-term fuel loads but generally results in increased amounts of fine fuels for the first few years after logging unless surface fuels are effectively treated. By reducing evapotranspiration, disturbing the soil organic horizon, and creating hydrophobic soils in some cases, fire can cause large increases in surface-water runoff, streamflow, and erosion. Through soil disturbance, especially the construction of roads, logging with ground-based equipment and cable yarding can exacerbate this effect, increasing erosion and altering hydrological function at the local scale. Effects on aquatic systems of removing trees are mostly negative, and logging and transportation systems that disturb the soil surface or accelerate road-related erosion can be particularly harmful unless disturbances are mitigated. Cavity-nesting birds, small mammals, and amphibians may be affected by harvest of standing dead and live trees, with negative effects on most species but positive or neutral effects on other species, depending on the intensity and extent of logging. Data gaps on postfire logging include the effects of various intensities of logging, patch size of harvest relative to fire size, and long-term (10+ years) biophysical changes. Uncertainty about the effects of postfire logging can be reduced by implementing management experiments to document long-term changes in natural resources at different spatial scales.

This synthesis provides an ecological foundation for management of the diverse ecosystems and fire regimes of North America, based on scientific principles of fire interactions with vegetation, fuels, and biophysical processes. Although a large amount of scientific data on fire exists, most of those data have been collected at small spatial and temporal scales. Thus, it is challenging to develop consistent science-based plans for large spatial and temporal scales where most fire management and planning occur. Understanding the regional geographic context of fire regimes is critical for developing appropriate and sustainable management strategies and policy. The degree to which human intervention has modified fire frequency, intensity, and severity varies greatly among different ecosystems, and must be considered when planning to alter fuel loads or implement restorative treatments. Detailed discussion of six ecosystems--ponderosa pine forest (western North America), chaparral (California), boreal forest (Alaska and Canada), Great Basin sagebrush (intermountain West), pine and pine-hardwood forests (Southern Appalachian Mountains), and longleaf pine (Southeastern United States)--illustrates the complexity of fire regimes and that fire management requires a clear regional focus that recognizes where conflicts might exist between fire hazard reduction and resource needs. In some systems, such as ponderosa pine, treatments are usually compatible with both fuel reduction and resource needs, whereas in others, such as chaparral, the potential exists for conflicts that need to be closely evaluated. Managing fire regimes in a changing climate and social environment requires a strong scientific basis for developing fire management and policy.

Forests of the Pacific Northwest have been an epicenter for the evolution of truffle fungi with over 350 truffle species and 55 genera currently identified. Truffle fungi develop their reproductive fruit-bodies typically belowground, so they are harder to find and study than mushrooms that fruit aboveground. Nevertheless, over the last five decades, the Corvallis Forest Mycology program of the Pacific Northwest Research Station has amassed unprecedented knowledge on the diversity and ecology of truffles in the region. Truffle fungi form mycorrhizal symbioses that benefit the growth and survival of many tree and understory plants. Truffle fruit-bodies serve as a major food souce for many forest-dwelling mammals. A few truffle species are commercially harvested for gourmet consumption in regional restaurants. This publication explores the biology and ecology of truffle fungi in the Pacific Northwest, their importance in forest ecosystems, and effects of various silvicultural practices on sustaining truffle populations. General management principles and considerations to sustain this valuable fungal resource are provided.

Population growth in Oregon, Washington, and Alaska is expected to increase demand for outdoor recreation on public land. This trend will be tempered by changes in the sociodemographic composition of the population. Among sociodemographic characteristics, different ages and incomes correspond to different participation rates. Although older Americans are participating more, participation is still lower among this group for active pursuits. Hence, as the population ages, demand for passive activities may increase. Low-income people participate at a much lower rate than higher income people in outdoor recreation, and the growing disparity between the wealthy and poor may create inequities in opportunities for participation. State recreation planning documents for Oregon, Washington, and Alaska have identified this issue as a significant concern for recreation providers. Another important factor in recreation trends in the region is ethnicity: different ethnic groups participate in outdoor recreation at different rates, exhibit some different preferences for specific activities, and use recreation sites in different ways. In Alaska, the number of Asian/Pacific Islanders is expected to quadruple by 2025; in Oregon, the Hispanic population may triple by 2025; and in Washington, both these segments of the population may double.

Timber availability, aboveground tree biomass, and changes in aboveground carbon pools are important consequences of landscape management.

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.

Sustaining farm and forest land has been an important goal in the United States because of the role these lands play in the livelihoods of rural residents while also providing desired open space benefits. However, land use policies to protect rural lands often involve a tension between balancing public interests regarding economic and open space goals with the private interests and property rights of farm and forest land owners.

The American Recovery and Reinvestment Act of 2009 aimed to create jobs and jumpstart the economy while addressing the Nation's social and environmental needs. The U.S. Department of Agriculture, Forest Service, received $1.15 billion in recovery funding to support projects in wildland fire management, capital improvement and maintenance, and biomass utilization. This volume contains eight individual case-study reports that describe how Forest Service economic recovery projects from around the United States are contributing to socioeconomic well-being in rural communities and investigates how forest restoration, conservation, and rural community development goals can be linked to promote healthy forests and healthy communities.

The United States, in partnership with 11 other countries, participates in the Montreal Process. Each country assesses national progress toward the sustainable management of forest resources by using a set of criteria and indicators agreed on by all member countries. Several indicators focus on nontimber forest products (NTFPs). In the United States, permit and contract data from the U.S. Forest Service and the Bureau of Land Management, in addition to several other data sources, were used as a benchmark to assess harvest, value, employment, exports and imports, per capita consumption, and subsistence uses for many NTFPs. The retail value of commercial harvests of NTFPs from U.S. forest lands is estimated at $1.4 billion annually. Nontimber forest products in the United States are important to many people throughout the country for personal, cultural, and commercial uses, providing food security, beauty, connection to culture and tradition, and income.

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.

The Forest Inventory and Analysis program collected, analyzed, and summarized field data on 37 field plots on the islands of Rota, Tinian, and Saipan in the Commonwealth of the Northern Mariana Islands (CNMI).

Late-successional and old-growth (LSOG) monitoring characterizes the status and trends of older forests to answer such questions as: How much older forest is there? Where is it? How much has changed and from what causes? Is the Northwest Forest Plan (the Plan) maintaining or restoring older forest ecosystems to desired conditions on federal lands in the Plan area? This assessment is the second in a continuous monitoring cycle. We initially reported on LSOG status and trends from 1994 to 2003 in the "10-year report." This document, the mid-cycle "15-year report," updates the assessment to 2006 in Washington and Oregon and to 2007 in California. The next major assessment will be the 20-year report.

Provides historical information on log harvest; employment in the forest industries; international trade in logs, lumber, and chips; and volume and average prices of sawtimber stumpage sold by national forests.

The American Recovery and Reinvestment Act of 2009 (the Recovery Act) aimed to create jobs and promote economic growth while addressing the Nation's social and environmental needs. The USDA Forest Service received $1.15 billion in economic recovery funding. This report contains key findings and lessons learned from a socioeconomic assessment of Forest Service Recovery Act projects. The assessment examines how Forest Service economic recovery projects at eight case-study locations around the United States are contributing to socioeconomic well-being in rural counties affected by the economic recession of 2007-2009. It also investigates how Forest Service mission-related work can be accomplished in a manner that creates local community development opportunities. This report is a companion to general technical report PNW-GTR-831, which contains the full case-study reports.

The past decade has seen resurgence in interest in gathering wild plants and fungi in cities. In addition to gathering by individuals, dozens of groups have emerged in U.S., Canadian, and European cities to facilitate access to nontimber forest products (NTFPs), particularly fruits and nuts, in public and private spaces. Recent efforts within cities to encourage public orchards and food forests, and to incorporate more fruit and nut trees into street tree planting programs indicate a growing recognition among planners that gathering is an important urban activity.

None of several types of chemotherapeutants applied before inoculation (antibiotics, metallic salts, systemic fungicides) prevented infection of sugar pine seedlings by white pine blister rust. DMSO (dimethyl sulfoxide) did not enhance the action of any material with which it was applied.

Concerns about forest health and the threat of wildfire across the Western United States increasingly provide the impetus for communities to find land management solutions that serve multiple interests. Funding and procedural changes over the past decade have positioned federal agencies to put greater emphasis on multistakeholder partnerships and public outreach efforts. Partnerships build slowly over time, but can result in a healthier resource, reduced fire risk, greater stability for agency planning processes, and more resilient communities. Drawing on interviews with stakeholders representing broad interests in a partnership between the Northeast Washington Forestry Coalition and the Colville National Forest, we examine some of the critical factors leading to the partnership's success and identify challenges along the way. We illustrate how the citizens of Colville, Washington, overcame conflicts by learning to communicate their interests and use existing resources to advance a variety of goals, ranging from fuels reduction and active forest management to roadless area and wilderness management. We highlight a set of important organizational themes that have emerged from Colville to provide managers and other stakeholders with ideas for similar efforts.

Nationally, there is growing public interest in and policy pressure for developing alternative and renewable sources of energy. Wind energy facilities in the Pacific Northwest expanded rapidly over the past decade, as a result of state policies that encourage wind energy development. While much of the development thus far has occurred on private lands, there is interest in expanding onto federal land. However, there are concerns about the impacts of wind energy on wildlife. Wind energy facilities have the potential to harm wildlife both directly through collisions with turbines and transmission lines, and indirectly by modifying habitat. This report synthesizes the available scientific literature on potential wind energy facility impacts to wildlife, with a focus on the Pacific Northwest (Oregon and Washington), and summarizes the current best management practices recommended in federal and state guidelines for wind energy development. Research gaps in our understanding of wind energy impacts on wildlife remain. Future research needs include long-term, multisite, experimental studies of wind energy impacts on wildlife, improved ability to estimate population-level and cumulative impacts of wind energy facilities on wildlife, and better knowledge of key wildlife species' migration and demography.

Cofiring of biomass and coal at electrical generation facilities is gaining in importance as a means of reducing fossil fuel consumption, and more than 40 facilities in the United States have conducted test burns. Given the large size of many coal plants, cofiring at even low rates has the potential to utilize relatively large volumes of biomass. This could have important forest management implications if harvest residues or salvage timber are supplied to coal plants. Other feedstocks suitable for cofiring include wood products manufacturing residues, woody municipal wastes, agricultural residues, short-rotation intensive culture forests, or hazard fuel removals. Cofiring at low rates can often be done with minimal changes to plant handling and processing equipment, requiring little capital investment. Cofiring at higher rates can involve repowering entire burners to burn biomass in place of coal, or in some cases, repowering entire powerplants. Our research evaluates the current status of biomass cofiring in North America, identifying current trends and success stories, types of biomass used, coal plant sizes, and primary cofiring regions. We also identify potential barriers to cofiring. Results are presented for more than a dozen plants that are currently cofiring or have recently announced plans to cofire.

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.

Interactions between forests, climatic change and the Earths carbon cycle are complex and represent a challenge for forest managers - they are integral to the sustainable management of forests. In this volume, a number of papers are presented that describe some of the complex relationships between climate, the global carbon cycle and forests.

This report is a compilation of six briefing papers based on literature reviews and syntheses, prepared for U.S. Department of Agriculture, Forest Service policy analysts and decisionmakers about specific questions pertaining to climate change.

Indigenous populations are projected to face disproportionate impacts as a result of climate change in comparison to nonindigenous populations. For this reason, many American Indian and Alaska Native tribes are identifying and implementing culturally appropriate strategies to assess climate impacts and adapt to projected changes. Traditional ecological knowledge (TEK), as the indigenous knowledge system is called, has the potential to play a central role in both indigenous and nonindigenous climate change initiatives. The detection of environmental changes, the development of strategies to adapt to these changes, and the implementation of sustainable land-management principles are all important climate action items that can be informed by TEK. Although there is a significant body of literature on traditional knowledge, this synthesis examines literature that specifically explores the relationship between TEK and climate change. The synthesis describes the potential role of TEK in climate change assessment and adaptation efforts. It also identifies some of the challenges and benefits associated with merging TEK with Western science, and reviews the way in which federal policies and administrative practices facilitate or challenge the incorporation of TEK in climate change initiatives. The synthesis highlights examples of how tribes and others are including TEK into climate research, education, and resource planning and explores strategies to incorporate TEK into climate change policy, assessments, and adaptation efforts at national, regional, and local levels.​

This list of recent publications and other products of the Pacific Northwest PNW Research Station is published four times a year. The first section shows items published by the PNW Research Station. The second section shows publications available elsewhere. In each section, items are grouped alphabetically by authors within categories. The list is available online and in pdf format.

On Wednesday, May 16, research ecologist Charlie Crisafulli will be available for field-based media interviews at Mount St. Helens, the volcano that erupted catastrophically 38 years ago this month.

OWASHINGTON, D.C., JUNE 11, 2018—The USDA Forest Service today released a report that will serve as the scientific foundation for land management planning in western Washington, western Oregon, and northern California.

This guidebook describes major biological and physical attributes of the 243-ha(600-ac) North Fork Silver Creek Research Natural Area (RNA), Josephine County, Oregon.

The North Cascadia Adaptation Partnership (NCAP) is a science-management partnership consisting of the U.S. Department of Agriculture Forest Service Mount Baker-Snoqualmie and Okanogan-Wenatchee National Forests and Pacific Northwest Research Station; North Cascades National Park Complex; Mount Rainier National Park; and University of Washington Climate Impacts Group.

The Integrated Landscape Assessment Project (ILAP) was a multiyear effort to produce information, maps, and models to help land managers, policymakers, and others conduct mid- to broad-scale (e.g., watersheds to states and larger areas) prioritization of land management actions, perform landscape assessments, and estimate cumulative effects of management actions for planning and other purposes.

We developed a process to address terrestrial wildlife species for which management for ecosystem diversity may be inadequate for providing ecological conditions capable of sustaining viable populations. The process includes (1) identifying species of conservation concern, (2) describing source habitats, and other important ecological factors, (3) organizing species into groups, (4) selecting surrogate species for each group, (5) developing surrogate species assessment models; (6) applying surrogate species assessment models to evaluate current and historical conditions, (7) developing conservation considerations, and (8) designing monitoring and adaptive management. Following the application of our species screening criteria, we identified 209 of 700 species as species of concern on National Forest System lands east of the Cascade Range in Washington state. We aggregated the 209 species of conservation concern into 10 families and 28 groups based primarily on their habitat associations (these are not phylogenetic families). We selected 32 primary surrogate species (78 percent birds, 17 percent mammals, 5 percent amphibians) for application in northeastern Washington, based on risk factors and ecological characteristics. Our assessment documented reductions in habitat capability across the assessment area compared to historical conditions. We combined management considerations for individual species with other surrogate species to address multiple species. This information may be used to inform land management planning efforts currently underway on the Okanogan-Wenatchee and Colville National Forests in northeastern Washington.

On February 4, 2014, a seven-member expert panel provided objective technical information on the potential effectiveness and feasibility of activities to manage raptors (northern harriers and great horned owls) to aid the recovery of western snowy plovers.

Sustaining the health, diversity, and productivity of national forests and grasslands is the mission of the U.S. Department of Agriculture (USDA) Forest Service.

Understanding the capacity to reduce wildfire risk and restore dry forests on Western national forests is a key part of prioritizing new accelerated restoration programs initiated by the Forest Service.

Over the past decade, wood-energy use in Alaska has grown dramatically.

Over the past decade, the use of wood for thermal energy in Alaska has grown significantly. Since 2000, nearly 30 new thermal wood-energy installations in Alaska have been established.

Northwest Forest Plan—the first 20 years (1994-2013): status and trends of northern spotted owl habitats.

The Aquatic and Riparian Effectiveness Monitoring Program focuses on assessing the degree to which federal land management under the aquatic conservation strategy (ACS) of the Northwest Forest Plan (NWFP) has been effective in maintaining and improving watershed conditions. We used stream sampling data and upslope/riparian geographic information system (GIS) and remote-sensing data to evaluate condition for sixth-field watersheds in each aquatic province within the NWFP area.

The Aquatic Conservation Strategy (ACS) of the Northwest Forest Plan guides management of riparian and aquatic ecosystems on federal lands in western Oregon, western Washington, and northern California.

Forest disturbances are increasing in extent and intensity, annually altering the structure and function of affected systems across millions of acres. Land managers need rapid assessment tools that can be used to characterize disturbance events across space and to meet forest planning needs.

Outdoor recreation is a central way that people interact with the natural environment. Federal land agencies are key providers of settings, facilities, and landscapes for recreation.

Natural resource professionals are often tasked with weighing the benefits and costs of changes in ecosystem services associated with land management alternatives and decisions. In many cases, federal regulations even require land managers and planners to account for these values explicitly. Outdoor recreation is a key ecosystem service provided by national forests and grasslands, and one of significant interest to the public. This report presents the most recent update of the Recreation Use Values Database, based on an exhaustive review of economic studies spanning 1958 to 2015 conducted in the United States and Canada, and provides the most up-to-date recreation economic values available. When combined with data pertaining to recreation activities and the quantity of recreation use, the recreation economic values can be used for estimating the economic benefits of outdoor recreation. The recreation economic value estimates provided in this report, whether from past research literature or from values constructed using our meta-analysis benefit function, are average consumer surplus per person per activity day.

This research models a wood pellet heating system at the Tlingit-Haida Regional Housing Authority in Juneau, Alaska, used to provide thermal energy to a 929-m2 warehouse, as an alternative to a heating system that burns more costly fossil fuels. Research objectives were to evaluate project economics of the pellet system and to conduct cost:benefit analysis on key variables (initial capital cost, fuel oil cost, and wood pellet cost). Economic results of interest included net present value, payback, internal rate of return, and cost:benefit ratio. Monte Carlo simulations were conducted using RETScreen software with the parameters of heating oil cost, wood pellet cost, fuel price escalation, and heating load. Cost:benefit analysis was conducted for capital cost versus wood fuel cost and also versus alternative fuel cost. This research found that economic performance was favorable over a wide range of normal operating conditions, even when paying a relatively high price for wood fuel. A pellet production facility in southeast Alaska could lead to lower wood fuel costs and even more favorable regional economics.

As part of the 10-year socioeconomic monitoring of the Northwest Forest Plan, this report evaluates changes in Forest Service and Bureau of Land Management (BLM) procurement contracting between 1990 and 2002 by asking, (1) How much and what kind of work did the Forest Service and BLM contract during this period, and (2) who received economic benefits from this procurement contracting? Procurement contracting is a particular focus of the socioeconomic monitoring because one expectation of the Northwest Forest Plan was that the Forest Service and BLM would create high-skill, high-wage private sector jobs in public land restoration through contracting to partially offset job losses in timber production, harvesting, and processing. This report finds that, to the contrary, the Forest Service reduced its contracting of land management activities on national forests in the Northwest Forest Plan area from a high of $103 million in 1991 to a low of $33 million in 2002. By contrast, BLM spending was fairly constant at just under $20 million annually. Both the Forest Service and the BLM changed the type of activities that they contracted, shifting from activities associated with intensive forest management such as tree planting in clearcuts to activities associated with ecosystem management. Contractors located near national forests and BLM lands and rural communities captured a similar proportion of contracts in both the earlier and later parts of the study period. However, the significant decline in Forest Service contract spending resulted in considerable decline in the amount of money flowing to rural communities through contracting. Thus, it is unlikely that federal land management contracting created a net increase in jobs to replace jobs lost in mills and logging operations in public lands communities.

In March 23-25, 2005, an international symposium on red alder was held at the University of Washington Center for Urban Horticulture in Seattle, WA. The symposium was entitled “Red Alder: A State of Knowledge” and brought together regional experts to critically examine the economic, ecological and social values of red alder. The primary goal of the symposium was to discuss new advances in the understanding of red alder biology and silviculture, changing market and nonmarket values, and the current regulatory climate for management of alder. This proceedings includes 14 papers based on oral presentations given at the symposium. These papers highlight some of the key findings from the history, ecology, biology, silviculture and economics sessions presented at the red alder symposium.

Rangeland exclosures installed primarily in the 1960s, but with some from the 1940s, were resampled for changes in plant community structure and composition periodically from 1977 to 2004 on the Malheur, Umatilla, and Wallowa-Whitman National Forests in northeastern Oregon. They allow one to compare vegetation with all-ungulate exclusion (known historically as game exclosures), all-livestock exclusion (known historically as stock exclosures), and with no exclusion (known as open areas). Thirteen upland rangeland exclosures in northeastern Oregon were selected and are presented with plant community trend data and possible causes of changes over time. Key findings are that moderate grazing by native ungulates afforded by the livestock exclosures generally stimulated bunchgrasses to retain dominance and vitality; native bunchgrasses can replace invasive rhizomatous plants given a reduction in disturbance over time; shrubs increased without ungulate use in shrubland communities; and invasive annuals that established following severe disturbances to the grassland community diminished with aggressive competition from perennial bunchgrasses.

This is the second in a series of periodic monitoring reports on northern spotted owl (Strix occidentalis caurina) population and habitat trends on federally administered lands since implementation of the Northwest Forest Plan in 1994. Here we summarize results from a population analysis that included data from longterm demographic studies during 1985–2008. This data was analyzed separately by study area, and also in a meta-analysis across all study areas to assess temporal and spatial patterns in fecundity, apparent survival, recruitment, and annual rates of population change.

Six of nine nonnative boreal conifers in three genera (Abies, Larix, and Pinus) regenerated in 11 to 31 years after they were introduced to mainland Alaska. Lodgepole pine (Pinus contorta var. latifolia Engel.) and the Siberian larches (Larix sibirica Ledeb. and L. sukaczewii N. Dyl.) were the most widely introduced species and will likely be the first nonnative conifers to naturalize. Siberian larch grew up to six times more stem volume than white spruce in the first 40 years on upland sites, but was susceptible to the larch sawfly and a blue stain pathogen carried by bark beetles. On productive sites, lodgepole pine appeared to grow more stem wood than white spruce for about 35 years after planting. Snowshoe hares and moose were the most serious pests of the nonnative conifers. Balsam fir (Abies balsamea (L.) Mill.) was the only species to regenerate in an established moss understory. Growth and age relationships were negative for all adequately sampled nonnative conifers and positive for native white spruce (Picea glauca (Moench) Voss). Data were insufficient to assess niche availability for commercial-use of productive nonnative conifers in mixed stands in Alaska. Survey results indicate that introduction and naturalization of noninvasive tree species may improve the diversity, stability, and productivity of managed forest ecosystems.

This report describes the evidence for invasion of Pacific Northwest streams by Atlantic salmon (Salmo salar) that have escaped from marine salmon farms, and assesses the potential impact of farmed salmon invasion on native fishes inhabiting streams on National Forest System lands. The current risk to streams on National Forest lands in the Pacific Northwest from Atlantic salmon invasions appears to be low and is limited to a few areas in northwest Washington and southeast Alaska. However, long-term risks may be substantial if fish continue to escape from marine rearing pens or freshwater hatcheries. The two greatest threats appear to be that (1) Atlantic salmon could transmit a serious disease or parasite to native fishes, and (2) escaped salmon could eventually adapt to local conditions, leading to self-sustaining populations. If Atlantic salmon populations are eventually established, this species' preference for swiftly flowing stream habitats could facilitate competition with currently at-risk species such as steelhead (Oncorhynchus mykiss). This could result in a pattern of expansion similar to that observed in other nonnative aquatic plants and animals, in which a prolonged early colonization period is followed by a rapid phase of exponential growth as breeding populations adapt to local conditions.