United States 

Department of Agriculture

Forest 

Service
Message From the Director

I am proud to present the Pacific Southwest Research Station’s 2017 Science Spotlight. In this document, we highlight research 

completed during the past year related to the four outcomes that our station strives to address: (1) forest landscapes that are 

resilient to disturbance, especially fire; (2) enhanced benefits to urban communities from the natural environment; (3) clean and 

reliable water resources; and (4) sustained ecological resources and services. 

We serve people and improve lives with our research, which spans a diversity of disciplines and an enormous geographical 

footprint. As you scan through these pages, take note of the relevance and rigor of our science, the value we place on connecting 

with people, the end users of our work, and the care we take in stewarding all of the resources with which we are entrusted to 

conduct this work. 

The forest resources-related challenges facing California, Hawaii, and the U.S.-affiliated Pacific Islands are significant. 

However, targeted science can inform policy and management so that the health, diversity, and productivity of these resources 

can be sustained to the greatest extent possible. 

The quality of our accomplishments is the result of the talent and dedication of our staff, partners, and collaborators, as well as 

the enduring support for our work that has allowed relevant science to emerge and develop into impactful findings.

Alexander L. Friend, Ph.D.

Station Director

Pacific Southwest Research Station

Vision and Mission

The Pacific Southwest Research Station is a leader in natural resources research 

through scientific excellence and responsiveness to the needs of current and future 

generations. Our mission is to develop and communicate science needed to sustain 

forest ecosystems and their benefits to society.

Cover: Castle Lake and Mount Shasta. Photo by Brittany Burnett.

This page: Climber on Mount Shasta. Photo by Nick Meyers.

2
Extramural funding received

Base research operations

Total funding

Funding shown by fiscal year in millions (US $)

2017

0 10 20 30

2016

2015

2014

2.3

21.4

25.2

20.1

5.1

23.7

5.1

22.1

27.2

3.5

22.2

26.7

Pacific Southwest Research Station: At a Glance

Headquartered in Albany, California, the Pacific Southwest (PSW) Research Station is part of 

the U.S. Forest Service’s Research and Development branch. Comprising 131 employees, PSW 

Research Station staff develop and communicate science used to sustain forest ecosystems and 

benefit communities. PSW Research Station scientists are engaged in research across a network 

of 12 experimental forests and ranges, two research watersheds, and eight research facilities 

throughout California, Hawaii, and the U.S.-affiliated Pacific Islands. 

Scientific pursuits are organized into five research units:

• Conservation of Biodiversity

• Ecosystem Function and Health

• Fire and Fuels

• Urban Ecosystems and Social Dynamics

• The Institute of Pacific Islands Forestry

Funding for research comes from federal budget allocations (base research operations) 

and cooperating agreements with other agencies, groups, and educational institutions 

(extramural funding).

3
Forecasting California tree mortality

An updated map enables forest managers to adapt management strategies by 

predicting the likelihood of future tree mortality from bark beetles throughout 

California. Pacific Southwest Research Station researchers and collaborators 

analyzed aerial survey data and variables known to influence bark beetle 

success, such as precipitation and stand density, to create the map. The map 

can be generated to forecast the likelihood of mortality 2 years into the future, 

enabling land managers to prioritize treatment locations to coincide with 

areas most likely to experience mortality.

Principal Investigator: Haiganoush Preisler 

Monitoring wildfire behavior in beetle-killed forests

Researchers at the Pacific Southwest Research Station are examining how 

wildfire behaves in forests with high levels of tree mortality from California’s 

prolonged drought and bark beetle epidemic. FireMapper 2.0, an airborne 

wildfire-mapping and remote-sensing system, uses thermal imaging 

technology to measure fire-spread rates, energy release or intensity, and 

spot-fire generation, as well as temperature gradients within the fire. These 

data provide valuable insights into wildfire behavior and severity in these 

novel environments; they also inform land managers about possible treatment 

strategies to mitigate these effects.

Principal Investigator: Phil Riggan

Curbing wildfire, invasive species in Hawaii with native plants

Invasive grass species are converting Hawaii’s dry forest landscapes 

into nonnative grasslands, decreasing native biodiversity and 

contributing to wildfire in these ecosystems. Borrowing from 

techniques used in the Intermountain West, researchers are experimenting with so-called greenstrips of native Hawaiian plants to 

break up swaths of fire-carrying grasses, while restoring native 

ecosystems. Chenopodium, a fast-growing, flowering native shrub 

from the amaranth family, proved to be the most effective greenstrip 

species for restricting invasive grass growth; it also exhibited the firelimiting properties of high moisture content and low heating values.

Principal Investigator: Susan Cordell

The tree mortality predictor 

map lets land managers 

know which parts of 

California are most likely 

to suffer tree mortality from 

bark beetle attacks.

This “greenstrip” of native Hawaiian vegetation has the potential to restrict 

invasive grass growth, while acting as a fuel break against wildfires.

FireMapper 2.0 captures an 

image of the 2017 Detwiler 

Fire in central California.

Kari Greer

The Thomas Fire, Ventura, 

California, Los Padres 

Nantional Forest, 2017

Phil Riggan

Haiganoush Preisler

Susan Cordell

Highly flammable 

grassland

Ecosystem 

fragment

Greenstrip using 

appropriate 

native species

Forest Landscapes That Are 

Resilient to Disturbance 

4
Sustained Ecological Services

“Snag islands” provide refuge for black-backed woodpeckers

Logging can negatively affect nesting densities for black-backed woodpeckers in burned forests; however, researchers discovered that 

these effects appeared to be buffered by uncut dead trees within and near the harvested areas. Following the 2007 Angora Fire near 

South Lake Tahoe, several clumps of standing dead trees, or snag islands, were retained for black-backed woodpeckers and other snagassociated species. Researchers systematically surveyed the postfire landscape for woodpecker nests for two years before and after 

salvage operations. The presence of nesting black-backed woodpeckers within snag islands and in other unlogged areas indicates that 

leaving dense stands of dead trees within the fire footprint may help balance the needs of wildlife and attain other management objectives.

Principal Investigator: Angela White

Stand productivity unaffected by logging, soil compaction

Long-term tree growth and understory revegetation were not affected by 

timber harvesting and related soil compaction. The results of a 20-year 

study showed near-complete tolerance by forest biomass to soil compaction 

and surface organic matter manipulation across a wide geographic range 

in California. The study compared results from varying soil compaction 

levels and varying harvest intensities, with or without postlogging control 

of competing vegetation. Soil compaction actually resulted in a 15-percent 

increase in planted tree growth, which was attributed to improved seedling 

survival along with reduced competition from understory vegetation. 

Controlling understory vegetation had the most pronounced effect in the 

study, with 68 percent greater tree growth in vegetation-controlled units 

compared to units where the understory went unmanaged.

Principal Investigator: Jianwei Zhang

Getting to the root of indigenous cultivation practices 

Roots were an important source of food for American Indians 

throughout California. Dozens of species of these geophytes were 

gathered across multiple plant communities, from salt marshes to 

deserts to chaparral to the open understories of coniferous forests 

and oak woodlands. Researchers have chronicled how indigenous 

people mastered the ecological requirements necessary for these 

“root foods” to flourish. Tending practices such as intentional 

burning, harvesting methods, and site cultivation have resulted in 

individual plants growing more vigorously with larger or more 

numerous roots, as well as growing more abundantly relative to 

comparable uncultivated areas.

Principal Investigator: Frank Lake

Leaving clumps of dead, 

standing trees (“snag islands”) 

serves as a refuge for blackbacked woodpeckers during 

salvage logging.

Jianwei Zhang

Angela White

Frank Lake

Soil compaction from logging operations was found to have no 

long-term effects on tree growth or site revegetation, according 

to a 20-year study.

American Indian 

traditional cultivation 

practices were found to 

increase productivity of 

root foods, such as these 

Indian potatoes found 

along the Salmon River 

in northern California.

5
Building bigger fires that produce less smoke

Under favorable weather and fuel conditions, land managers can use prescribed fire in 

large areas of forest while keeping daily emissions below levels likely to cause harm to 

people in downwind communities. To better predict smoke effects from prescribed fires, 

Forest Service researchers have created a framework that takes advantage of smoke 

and air quality modeling software, as well as demographic information already used by 

fire, air quality, and public health managers. They demonstrated that the smoke from an 

uncontrolled wildfire in the central Sierra Nevada was several times greater than smoke 

from prescribed fires in the same area. The framework is being used in a 3-year project 

on the Eldorado National Forest in California’s Sierra Nevada foothills that will treat 

8,000 acres with prescribed fire.

Principal Investigators: Jonathan Long, Malcolm North, and Lee Tarnay

Compiling the nation’s largest urban tree growth database

City planners across the United States are benefiting from the largest and most precise 

tree growth database in the country, featuring growth models for 171 urban tree 

species across 16 U.S. climate zones. The Urban Tree Database is the culmination of 

14 years of work in which Pacific Southwest Research Station researchers analyzed 

more than 14,000 trees throughout the United States. Moving beyond traditional 

growth models that predict a tree’s height and diameter, this new database incorporates 

365 sets of tree growth equations, enabling urban foresters to plan for potential carbon 

sequestration, crown dimensions, foliage amounts, and air pollutant absorption. 

Principal Investigator: Greg McPherson

Turning kids onto nature through other kids 

The best way to talk to kids about nature is through other kids. Themes based on unique experiences, 

challenges, adventures, and social connections most resonated with Los Angeles-area youth participating 

in a communications workshop with Pacific Southwest Research Station researchers. Young people from 

underserved populations were trained to serve as peer communicators; they developed messages aimed 

at connecting their peers to the outdoors through photos, video, and social media messages. Researchers 

found that messages designed by these peer communicators were more appealing to recipients compared 

to messages developed by adults. Researchers developed a toolkit from the exercise to share with land 

managers who might be interested in adopting a youth peer communications network across social media.

Principal Investigator: Pat Winter

Under controlled conditions, smoke from 

prescribed fires can be several times less than 

smoke generated by uncontrolled wildfires.

“Urban Tree 

Database and 

Allometric 

Equations” 

provides the 

largest and most 

precise growth 

database for 

urban trees in the 

United States.

Jonathon Long

Trees ablaze during the 

Hunter Fire, June 2006.

U.S. Forest Service

Enhanced Benefits to Communities 

6
Tracking landslide sediment to unearth water quality 

Accurate assessments of the amount and duration of sedimentation in water after landslides help land managers better estimate the 

accumulative effects on water quality and aquatic organisms. Researchers found that, depending on the size of the landslide, soil and 

debris deposited in streams can stay suspended in the water column for up to 8 years. While the majority of displaced material from 

landslides remains on the hillslope or adjacent to the stream or river channel, in two large slide events, up to 15 percent of the slide 

volume was found in the stream. Stream sedimentation can remain affected for years after a landslide owing to bank erosion and 

channel incisions from wood and debris. 

Principal Investigator: Elizabeth Keppeler

Invasive plants negatively affect Hawaiian 

stream species 

Reduced streamflow caused by invasive plants and low precipitation 

can result in reduced numbers for species that filter drinking water 

and provide important food sources. Researchers found that decreased 

streamflow in Hawaiian streams correlated with smaller and fewer native 

shrimp, as well as an increase in brown spot disease, which is lethal 

to these shrimp. Researchers also found the number of eggs on female 

shrimp decreased along the declining streamflow gradients. 

Principal Investigator: Rich MacKenzie

Incorporating fish behavior to improve stream restoration

Land managers can better estimate how restoration 

designs will affect valued fish species, such as coho 

salmon, with a new model called InSTREAM that 

offers greater insight into how fish respond to stream 

channel characteristics, water conditions, other fish, and 

predators. Models that reflect individual fish behavior 

can provide managers with simulations that also account 

for daily, seasonal and annual variations, allowing 

them to make projections across various time frames. 

Previous models only used generalized assumptions 

about fish populations and habitat conditions. This new 

model gives land managers more useful estimates of 

how fish will respond to various restoration strategies.

Principal Investigator: Bret Harvey

Researchers discovered that up 

to 15 percent of a landslide’s 

volume can wind up in a stream, 

where sediment can remain 

suspended in the water column 

for up to 8 years.

Reduced streamflows in Hawaii have been linked to fewer and 

smaller aquatic species, such as these native shrimp.

A new computer model gives land managers more useful estimates of how fish will 

respond to restoration options for streams such as this.

Clean and Reliable Water Resources

Elizabeth Keppler

Bret Harvey

Richard MacKenzie

7
Station Director

Dr. Alexander L. Friend

(510) 883-8832

afriend@fs.fed.us

Assistant Director, Business Operations

Colleen Schneider

(510) 883-8834

ckschneider@fs.fed.us

Director, Partnerships

Dr. Ricardo D. Lopez

(808) 747-4080

rdlopez@fs.fed.us

Director, Research Planning

A.J. Duggan

(510) 883-8836

aaduggan@fs.fed.us

Program Manager, Conservation of Biodiversity

Dr. Patricia Manley

(530) 621-6882

pmanley@fs.fed.us

Program Manager, Ecosystem Function and Health

Dr. Chrissy Howell

(510) 883-8839

cahowell@fs.fed.us

Program Manager, Fire and Fuels; 

Urban Ecosystems and Social Dynamics

Joshua Wilson

(951) 680-1558

joshuawilson@fs.fed.us

Director, Institute of Pacific Islands Forestry 

Dr. Susan Cordell

(808) 854-2601

scordell@fs.fed.us

Locations

PSW-Albany (Headquarters)

800 Buchanan Street

Albany, CA 94710-0011

Phone: (510) 883-8830

Fax: (510) 883-8858

PSW-Arcata

1700 Bayview Drive

Arcata, CA 95521-6013

Phone: (707) 825-2900

Fax: (707) 825-2901

PSW-Davis

1731 Research Park Drive

Davis, CA 95618

Phone: (530) 759-1700

Fax: (530) 747-0241

PSW-Fresno

2081 E. Sierra Avenue

Fresno, CA 93710-4639

Phone: (559) 323-3200

Fax: (559) 297-3355

PSW-Hilo, Institute of Pacific 

Islands Forestry

60 Nowelo Street

Hilo, HI 96720

Phone: (808) 933-8121

Fax: (808) 933-8120

PSW-Placerville, Institute of 

Forest Genetics

2480 Carson Road

Placerville, CA 95667

Phone: (530) 622-1225

Fax: (530) 622-2633

PSW-Redding

3644 Avtech Parkway

Redding, CA 96002

Phone: (530) 226-2530

Fax: (530) 226-5091

PSW-Riverside

4955 Canyon Crest Drive

Riverside, CA 92507

Phone: (951) 680-1500

Fax: (951) 680-1501

PSW Research Station Organization

Credits

Editor—A.J. Duggan

Writer—Paul Meznarich

Graphic Design—Jason Blake

PDF version available at http://www.fs.fed.us/psw/about/accomplishments/

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