USDA Forest Service

Pacific Northwest Research Station

Pacific Northwest Research Station
333 SW First Ave.
Portland, OR 97204

(503) 808-2100

US Forest Service
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» Understanding Habitat Needs

Sagebrush and Sage-grouse

Green Cities Research Alliance
Photo by Michael Wisdom

For decades, greater sage-grouse populations have been in dramatic decline across their North American range in response to the harmful effects of various human activities and land uses. To better understand the impacts of land use and habitat changes on sage-grouse, research wildlife biologist Michael Wisdom and colleagues used novel landscape modeling methods to conduct a comprehensive, rangewide analysis. The study considered 22 environmental factors in areas currently inhabited by sage-grouse compared to areas where the species is locally extinct. The researchers identified threshold values for the amount of sagebrush critical to sage-grouse persistence—addressing a key question about the species’habitat requirements—and also revealed the potentially negative impacts of communication towers and power lines on the species’occurrence.

For more information: Sage-Grouse on the Edge: Understanding and Managing Western Landscapes for Their Survival, Science Findings 142:

Contact: Michael Wisdom,

Where the Snow May Go

Forests Inside Out!
Photo by Cathy Raley

Wolverines live in areas that support persistent snow cover through mid May. Even in summer when the snow has melted, wolverines stay within these bioclimatic envelopes. Their habitat needs make the species especially vulnerable to climate-induced changes in snow timing and duration.

Research wildlife biologist Keith Aubry and colleagues modeled the distribution of snow cover within the Columbia, Upper Missouri, and Upper Colorado River Basins to identify likely impacts of a changing climate in these three basins under several global climate modes. The researchers estimated snow cover using a hydrologic model based on patterns in temperature and precipitation. Their modeling revealed that roughly two-thirds (67%) of predicted spring snow cover will persist within the study area through 2030 and 2059, and just over one-third (37%) will persist through 2070 and 2099. Maps based on this output identify areas where losses in snow cover might be greatest and which areas would retain snow cover throughout the 21st century. This information can help wildlife managers anticipate and plan for habitat isolation.

For more information: Climate Change Predicted to Shift Wolverine Distributions, Connectivity, and Dispersal Corridors:

Contact: Keith Aubry,

Seasonal Habitat Changes

Inner City Youth Institute
Photo by Rhonda Mazza

As instream conditions change throughout the year, juvenile coastal cutthroat trout, steelhead, and coho salmon move to different parts of the steam. Along with water levels, these movements are likely triggered by changing needs as the young fish grow and by inter- and intraspecies competition. Side channels and valley floor tributaries (5% of the available habitat), for example, contained 20% to 60% of the total coho salmon fry in the basin in the spring. Abundance in these areas declined as streamflow decreased from June to August in this coastal Oregon stream. Pools, generally created by the presence of large woody debris, were very important for older juvenile salmonids. Research fish biologist Gordon Reeves and colleagues also found that cutthroat trout congregated in the uppermost reaches, steelhead occupied the lowest reaches, and coho salmon inhabited the middle reaches.

This study demonstrates that basinwide distribution of salmonids varies among species, age classes, seasons, and years. This information can help fish managers responsible for developing management options and evaluating likely impacts of proposed actions on salmon habitat.

For more information: Seasonal Changes in Habitat Availability and the Distribution and Abundance of Salmonids Along a Stream Gradient from Headwaters to Mouth in Coastal Oregon:

Contact: Gordon Reeves,

A Focus on Forage

Urban Forests and Housing Costs
Photo by Alaska Department of Fish and Game

The Forage Resource Evaluation System for Habitat is a tool to quantitatively evaluate the quantity and quality of available food resources for deer. Research wildlife biologist Tom Hanley and colleagues developed the system to help wildlife biologists and resource managers compare different parts of a landscape at different times and under different conditions based on their suitability to support Sitka black-tailed deer in southeast Alaska. Users input the available biomass and nutritional quality of a habitat’s food resources and the metabolic requirements of deer, which vary depending on season and reproductive status. The model then generates a variety of outputs, including the number of days the landscape’s food resources can support deer. Although the tool was developed for black-tailed deer in Alaska, it also can be applied to other species of deer elsewhere in the world.

For more information:

Contact: Tom Hanley,

Featured Scientist

Beckey BittnerSherri Johnson is a research ecologist with the station’s Ecological Process and Function program. She also is the lead scientist at the H.J. Andrews Experimental Forest. Her research examines the complex interactions between forests and streams so that potential impacts can be better understood. Johnson and her colleagues have been analyzing long-term stream flow and stream chemistry data to evaluate trends over time in nitrogen dynamics from 23 undisturbed watershed across 11 experimental forests. In a different project, she has been studying uptake processes of nitrogen in streams. Nitrogen is a critical nutrient for all organisms, and Johnson found that half of one form—ammonium—was taken up over short travel distances in the stream, with the rest being converted to another form and transported downstream. Johnson’s research has also revealed that forest type is not a good predictor of concentrations of in-stream nitrogen. Johnson can be reached at and (541) 758-7771.

Tools and Software

Habitat Connectivity

i-TreeHabitat connectivity is a major focus of conservation biology. Fragmented landscapes can reduce gene flow and genetic diversity in wildlife populations, putting species at greater risk for extinction. A new framework helps managers and wildlife planners design wildlife corridors that improve connectivity in fragmented landscapes. The framework uses expert opinion as a starting point and then either validates its assumptions or identifies a peak of support for a new model more highly related to genetic isolation. Recently, the framework was used to study a population of mountain goats in a fragmented landscape in the Cascade Range. It is also being used by the Washington Department of Transportation to assess landscape connectivity along the I-90 corridor.

For more information:


US Forest Service - Pacific Northwest Research Station
Last Modified: Tuesday,05August2014 at09:42:16CDT

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