U.S. Forest Service

Pacific Southwest Research Station

DEPAR TMENT OF AGRICULT URE

Serving California, Hawaii, and the Pacific Islands

©Michael Balint

2016 Accomplishments Report
I am proud to present the Pacific Southwest 

Research Station’s 2016 Accomplishments Report. 

Our station is focused on science that contributes 

to four key outcomes: (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 research that spans a diversity of disciplines 

and has an enormous geographical footprint. As you scan through the pages ahead, I 

invite you to observe the relevance and rigor of our science, the value we place on 

connecting with people and the end users of our work, and the care we take in 

stewarding the resources with which we are entrusted. 

California, Hawaii, and the U.S.-affiliated Pacific Islands face substantial challenges 

related to forest resources. 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, for the benefit of current and future 

generations. To name a few of these challenges:

Vision and Mission

The Pacific Southwest 

Research Station is a 

world leader in natural 

resources research 

through our 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.

Message from the Director

• Recently, we have seen massive tree mortality in the Sierra Nevada. 

• Wildfire suppression is using an ever-increasing share of the Forest Service budget 

at the expense of other mission work, including research. 

• Conflicts associated with the management of public forests continue and intensify 

as changes in forest conditions affect biodiversity and productivity. 

• Water resources remain scarce in California, making their management 

controversial.

• More than 90 percent of our citizens live in urban areas, with significant numbers not 

sharing in the significant values offered by trees and green spaces.

• Invasive species, pathogens, and changes in climate pose increasing threats to 

ecosystems in Hawaii and the Pacific Islands. 

In the past year, we have made substantial progress toward addressing each of these by 

documenting the ecological, social, or economic phenomena at play, then communicating 

these findings to land managers and decisionmakers. The quality of accomplishments we 

report derives from the talent and dedication of our staff as well as our long-time 

collaborators and partners/supporters. Given this robust research and stakeholder 

community, I look forward to another successful year in 2017!

Alexander L. Friend, Ph.D.

Station Director, Pacific Southwest Research Station

About Us

The Pacific Southwest Research Station 

(PSW) represents Forest Service Research 

and Development in California, Hawaii, 

and the U.S.-affiliated Pacific Islands. Our 

region has the lowest, driest desert in the 

country, the highest elevations within the 

48 contiguous states, and the wettest tropical forests. An abundant diversity of native 

plants and animals and nearly half of the 

nation’s threatened and endangered species 

live in this region. At PSW we develop and 

deliver science to help inform decisions 

about natural resources management and 

conservation. Much of our work is accomplished in cooperation with other research 

institutions, such as universities, and state 

and other federal agencies.

Message from the Director, Vision and Mission
Forest Service at a Glance

The mission of the U.S. Forest Service, a federal agency under the U.S. Department of Agriculture, 

is to sustain the health, diversity, and productivity of the nation’s forests and grasslands to meet the 

needs of present and future generations. Established in 1905, the Forest Service: 

• Manages 193 million acres of national forests and grasslands.

• Shares responsibility, working in concert with state and local agents, for the stewardship 

of about 500 million acres of nonfederal rural and urban forests.

The Forest Service comprises several major branches that work together to manage the nation’s 

forests and protect global forest resources:

• The National Forest System sustains healthy terrestrial and aquatic ecosystems while 

addressing the need for resources, commodities, and services. This system is divided 

into nine regions. 

• State and Private Forestry helps private landowners, state forestry organizations, tribes, 

and communities achieve forest management, protection, and utilization objectives through 

a wide range of cooperative programs in the State and Private Forestry mission area.

• Research and Development provides long-term research, scientific knowledge, and tools 

that are used to manage forests and rangelands across the United States and overseas. The 

Forest Service has seven research stations with research units located throughout the 

United States, Puerto Rico, and the Pacific.

• International Programs promotes sustainable forest management and biodiversity 

conservation internationally.

• Law Enforcement and Investigations enforces federal laws and regulations governing 

national forest lands and resources.

The Forest Service at Work 

in the Pacific Southwest Region

California and Hawaii are located in the Pacific Southwest 

Region (Region 5) of the Forest Service. The Pacific 

Southwest Research Station (PSW), headquartered in 

Albany, California, partners with 18 national forests in 

California, and with State and Private Forestry programs 

throughout California, Hawaii, and the Pacific Islands.

Leaders of Region 5 and PSW have a common goal of 

retaining and restoring the ecological resilience of national 

forest lands to achieve sustainable ecosystems that provide 

a broad range of services to humans and other organisms. 

Combined effects of changing climate and hydrologic 

patterns, unhealthy forests, and rapidly growing human 

populations are resulting in increasingly over-allocated 

and undervalued ecosystem services (especially water); a 

dramatic increase in large wildfires, floods, and insect and 

disease outbreaks; threats from terrestrial and aquatic 

invasive species; and a growing need to revitalize rural 

economies in California, Hawaii, and the Pacific Islands. 

Region 5 and PSW are facing these challenges together 

and through collaboration with external partners around 

watershed restoration and forest resiliency.

ROCKY

MOUNTAIN 

RESEARCH

STATION

NORTHERN 

RESEARCH 

STATION

INTERNATIONAL 

INSTITUTE OF

TROPICAL 

FORESTRY

R1

Northern

R2

Rocky 

Mountain

R10

Alaska

R5

Pacific

Southwest

R4 

Intermountain

R6 

Pacific 

Northwest

R3 

Southwest

R9

Eastern

FOREST

PRODUCTS

LABORATORY

FOREST

PRODUCTS

LABORATORY

SOUTHERN

RESEARCH

STATION

SOUTHERN

RESEARCH

STATION

PACIFIC

NORTHWEST

RESEARCH

STATION

PACIFIC

SOUTHWEST

RESEARCH

STATION

ROCKY

MOUNTAIN 

RESEARCH

STATION

R8

Southern

LEGEND

Pacific Southwest Research Station

Pacific Northwest Research Station

Rocky Mountain Research Station

Northern Research Station

Southern Research Station

Forest Service Regional Boundary

Station Headquarters

International Institute of Tropical Forestry

Forest Products Laboratory

PACIFIC 

SOUTHWEST 

REGION

National Forests and Grasslands

Modoc

Los Padres

Angeles San Bernardino

Cleveland

Sequoia

Sierra

Plumas

Tahoe

Eldorado

Stanislaus

Mendocino 

McClellan

Regional Facility

Regional

 Office

Six

Rivers

Shasta

Trinity

Klamath

Inyo

Lassen

Plumas

Lake Tahoe Basin McClellan Management Unit Regional Facility

Regional

 Office

Tahoe

Eldorado

Six

Rivers

Klamath

Shasta

Trinity

Mendocino 

Inyo

Sierra

Stanislaus

Lassen

Modoc

Angeles San Bernardino

Cleveland

Sequoia

Los Padres

Los Padres

Forest Service at a Glance
Pacific Southwest Research Station 

at a Glance

Scientists and staff of the Pacific Southwest Research Station (PSW) work across 8 laboratories, 12 experimental forests and ranges, and 2 research watersheds comprising the station’s 

facilities in California and Hawaii. Research is also conducted in more than 90 research 

natural areas linked to a nationwide system of nonmanipulative research, monitoring, and 

educational opportunities. Research is organized into five research units:

1. Institute of Pacific Islands Forestry

Scientists conduct tropical ecosystem research and technology transfer. Research furthers sound management, conservation, 

and restoration of grassland, forest, and wetland ecosystems and landscapes in Hawaii, Guam, American Samoa, Northern 

Mariana Islands, Marshall Islands, Micronesia, and Palau (see Pacific Islands map below). 

2. Conservation of Biodiversity Program

Scientists conduct research on genes, species, habitats, landscapes, and the biological processes necessary to maintain a 

diversity of organisms and functioning ecosystems. Research focuses on enhancing the conservation of plant and animal 

species and habitats, and the restoration and maintenance of native ecosystems.

3. Ecosystem Function and Health Program

Scientists examine forest function and conduct research to protect and preserve water, air, and soil resources while 

considering the effects of a changing climate, unpredictable precipitation, air pollution, and constant threats from insect 

pests and plant pathogens.

4. Fire and Fuels Program

Scientists conduct research on how fuel types and conditions affect fire behavior and how physical properties of fuels 

influence fire severity and intensity. Research includes decision-support models that analyze risk, resource allocation 

economics, and fire-danger forecasting. 

5. Urban Ecosystems and Social Dynamics Program

Scientists examine the interconnections of people and natural resources. Research focuses on developing knowledge and 

tools in natural resources management to better serve the public, and on connecting urban dwellers with public lands 

through urban forestry and social science research.

Workforce 

• Total station workforce: 222 employees

• Permanent workforce: 143 employees

• Temporary workforce: 79 employees

• Of the permanent workforce, 

40 employees (28%) are 

research scientists.

• Workforce (temporary and 

permanent) actively conducting 

research: 98 employees

PSW’s area of responsibility also includes six Pacific Island U.S. territories and U.S.-affiliated republics.

Extramural funding received

Base research operations

Total funding

Funding shown by fiscal year in millions (US $)

2016

0 10 20 30

2015

2014

2013

2.3

21.4

23.7

5.1

22.1

27.2

3.5

22.2

26.7

2.1

22.5

24.6

Science Delivery

• PSW website visits: 155,325

• Twitter followers (@usfs_psw): 

2,024 

• Publications: 188

• Media mentions: 135

Top Website Visits

• PSW homepage: 9,663 visits

• Biocontrol for strawberry guava: 

5,777 visits

• Urban forestry: 3,899 visits

• Series reports: 3,296 visits

• Publications: 3,046 visits

Top News Stories

• Illegal marijuana farms threaten 

fishers

• Big-brained mammals at greatest 

risk of extinction

• Rapid ‘Ohi’a Death: The disease 

that’s killing native Hawaiian trees

• Weasels: Smart, fierce, and built 

to hunt

• California “street tree” benefits 

valued at $1 billion

Funding 

Pacific Southwest Research Station at a Glance
Community Involvement

Young citizen scientists monitor deadly amphibian fungus

PSW scientists have been helping youth with the 

Bilingual McKinleyville Ecoclub monitor a deadly 

fungus that is threatening amphibian communities 

along California’s northern coastal forests. Youths aged 

4 to 16 caught frogs and salamanders, then administered a skin swab to test for Batrachochytrium dendrobatidis, a pathogen that has reduced populations of 

more than 200 amphibian species worldwide. Of the 

seven species and 155 amphibians tested, five species 

and 26 individuals tested positive for the fungus. The 

findings, published in the July 2016 issue of the Journal 

of Wildlife Diseases, demonstrate the ability of children 

to participate in meaningful citizen science projects.

Event fosters tribal climate leaders

More than 90 students from indigenous communities 

across the United States gathered in early July to learn 

about climate change during an Inter-Tribal Youth 

Climate Leadership Congress in Shepherdstown, West 

Virginia. PSW research ecologist Frank Lake, a descendant of California’s Karuk people, delivered the keynote 

address, led a workshop session on “Tribal Forestry as 

Impacted by Climate Change,” and staffed a career fair 

to share how he incorporates traditional ecological 

knowledge into his profession. The congress was organized by the U.S. Forest Service, U.S. Fish and Wildlife 

Service, and several other federal agencies.

Youths with the Bilingual McKinleyville Ecoclub helped PSW researchers monitor for a deadly fungus affecting 

amphibians around the world.

PSW research ecologists Frank Lake (left) discusses science- and natural 

resource-based careers with attendees during a career fair at the 

Inter-Tribal Youth Climate Leadership Congress.

BioBlitz explores Hawaiian dry forest ecology

PSW researchers, in partnership with the Hawaii 

Division of Forestry and Wildlife, the University of 

Hawaii at Manoa, and the Forest Service’s National 

Partnership Office, hosted 250 fourth-graders in 

September for a “Bio-Cultural Blitz” at the Pu‘u 

Wa‘awa‘a Dry Forest Unit of the Hawaii Experimental 

Tropical Forest. Students were traditionally welcomed 

by native Hawaiian descendants of Pu‘u Wa‘awa‘a and 

spent the day visiting stations highlighting the biocultural significance of endangered dry forests—from 

botany and soils to wildlife and insects to cultural 

geography and indigenous resource management—

while engaging in hands-on activities.

PSW forest research featured at San Francisco event

PSW was the main attraction in September during the 

California Academy of Sciences’ NightLife event. 

About 1,500 people attended the after-hours event, 

which featured forest research. PSW researchers shared 

information about bark beetles, tree mortality, fire 

ecology, and forest resiliency. Interactive exhibits 

included a beanbag-toss game illustrating how cavitydwellers make use of snags, a pine cone guessing game, 

a demonstration showing values of urban trees, and a 

beetle and butterfly display. Smokey Bear also made an 

appearance, spreading his wildfire prevention message.

Fourth-graders learned about the biological importance and cultural significance of Hawaii’s endangered dry forests during a “Bio-Cultural Blitz” in September at the Pu‘u Wa‘awa‘a Dry Forest.

PSW scientists shared their latest research during a forest-themed NightLife 

event in September at the California Academy of Sciences in San Francisco.

Community Involvement
Ecosystem Function and Health

Shelter from the warm

Climate refugia could mitigate impacts of climate change

Once considered an icon of climate vulnerability, the 

American pika is now becoming a model for climate 

resiliency. PSW scientists studied how the pika’s 

behaviors have changed in the face of warming temperatures. This research has highlighted the importance of climate refugia, or areas across a landscape 

providing climate stability. Pikas take advantage of 

“air conditioned” shaded rocky interiors on mountain 

slopes to buffer themselves from a summer day’s heat. 

Researchers also have observed pikas adapting their 

behavior to be more active during cooler times of the 

day and less active in the midday heat. These findings 

give pause to climate assessments that rely solely on 

regional surface air temperatures to predict species 

vulnerability to changing climates, and point instead 

to the importance of microclimates, the temperatures 

within specific local habitats for wildlife.

Principal investigator: Connie Millar

Feasts from famines

Increased drought conditions a boon for attack by bark beetles, but not fungal pathogens

Pikas are demonstrating how species can adapt to changing climates by finding sheltered areas to reside in or modifying their behavior to avoid the heat of the day. 

Current climate trends suggest that we could see higher 

temperatures as well as an increase in the frequency 

and severity of droughts in the Western United States. 

Such conditions are likely to bolster some forest threats, 

while reducing the impacts of others. A PSW scientist 

and colleagues from academia, the Rocky Mountain 

Research Station, and the National Park Service reviewed and synthesized research concerning the effects 

of drought on forest insects and diseases. They found 

that forests are able to withstand bark beetle onslaughts 

under moderate drought conditions, but are 

overwhelmed by severe drought conditions. Forest 

defoliators show no consistent responses to drought. At 

the same time, evidence suggests that pathogens whose 

life cycle depends directly on moisture will have less 

impact during droughts, while those that depend on the 

availability of stressed hosts will have more impact. 

Understanding these relationships will better allow land 

managers to develop and implement treatments, such as 

thinning, that help mitigate future disturbances.

Principal investigator: 

Chris Fettig

Air quality up in smoke

Air pollutants and fine particulate matter measured, tracked during mega-fire

When a 1.7-million-acre wildfire burned within the 

vicinity of a Canadian oil field, preexisting air monitoring devices detected a seven- to eightfold increase 

in nitrogenous pollutants in the air. PSW researchers 

tracked the output of pollutants throughout the threeand-a-half-month course of the 2011 Richardson Fire 

in northern Alberta. After the first month or so of 

burning, levels returned closer to normal as the fire 

moved farther from the sensors. Little change was 

detected in sulfuric pollutants from prefire levels. 

The amount of nitrous pollutants on the landscape 

increased by two to four times the amount from any 

of the previous three summers, but never reached toxic 

levels. The study provides public health officials with 

new insights into the types and amounts of pollutants 

that can affect an area during severe wildfires. 

Principal investigator: Mark Fenn

Severe drought can create conditions that 

foster bark beetle infestations, leading to 

mass tree mortality, such as what is being 

seen in California’s Sierra Nevada. 

Corrosive nitric acid vapor spiked during the Richardson Fire in 2011. 

Concentrations of the pollutant decreased a year following the fire, but 

not to the same levels preceding the fire.

Ecosystem Function and Health Program
Fire and Fuels

Suitable shrubs for future climates

Research identifies native plants ideal for changing 

climatic conditions

PSW researchers and collaborators have created an 

inventory of native chaparral and coastal shrub species for southern California that identifies habitat 

preferences, growth characteristics, and possible 

restoration uses. Their work includes maps of possible 

changes to habitat suitability under future climate 

conditions to guide plant selections for long-term 

survival. Whether replanting a landscape affected by 

wildfire or restoring a tract of land to its natural state, 

establishing native shrub communities suitable to 

current and future climates is paramount. Shrubs play 

an important role in nature by providing habitat for 

wildlife and stabilizing soils and slopes, as well as 

storing carbon and producing oxygen. 

Principal investigator: Jan Beyers

Second-hand choke

Plants exposed to air pollution re-release pollutants 

when burned

Vegetation exposed to high levels of nitrogen oxide 

pollutants later released smoke containing up to 30 

percent more of the pollutant when burned than does 

vegetation from areas low in nitrogen deposition. The 

effects of nitrogen oxides from air pollution on the 

environment are well documented, from a reduction in 

water quality to acidification of soil, which reduces 

plant vigor and vitality. But the effects of nitrogen 

deposition don’t stop on the forest floor, according to 

PSW research. The findings indicate that regional air 

quality also should be taken into account when considering the atmospheric emissions from wildfires.

Principal investigator: David Weise

Refueling the fire

Severe wildfires creating conditions that promote 

future extreme fires

After decades of wildfire suppression, current environmental conditions are resulting in fires burning at a 

greater intensity across a greater expanse of landscape 

than historical levels. But instead of putting ecosystems back into equilibrium, new research suggests that 

the aftermath of some fires is paving the way for even 

greater fires in the future. Moderate- to high-severity 

wildfires are leaving behind a greater amount of dead 

standing trees and an influx of fast-growing invasive 

shrubs in their wake, which, when exposed to wildfire 

several years later, are again producing severe fires 

with repeatable effects. Knowing the postfire conditions fueling severe reburns can guide land managers 

in implementing strategies that disrupt the cycle.

Principal investigator: Brandon Collins

Sugar bush (Rhus ovata) is a useful shrub for southern California restoration projects because it grows fairly easily and resprouts after wildfire. 

Smoke from vegetation exposed to high levels of nitrogen oxide pollutants contained up to 30 percent more of the pollutant than smoke from vegetation in less polluted areas.

Initial fire Reburn fire

Negative feedback, greater stability Positive feedback, decreased stability, potential state change

Moderate severity: overstory partially removed, 

increased surface fuels and shrub colonization

Low severity: overstory intact, reduced 

surface fuels and tree density

High severity: shrub replacement, 

snags removed

High severity: overstory removed, shrub 

colonization, increased surface fuels

Low severity: overstory intact, reduced 

surface fuels, increased tree regeneration

Initial condition: fire excluded,

mixed-conifer forest

Arlee Montalvo, Riverside-Corona Resource Conservation District

Fire and Fuels Program
Long-Range Research

Spotty results

California spotted owl numbers 

decreasing in some areas, rising in others

California spotted owl populations in and around the 

Sierra Nevada have declined within two study sites, but 

rose at a third. For the past 25 years, PSW researchers 

have been monitoring spotted owl population changes. 

On two study sites located across a mixture of national 

forest and private lands, researchers saw a decline in 

population from the previous year. However, spotted 

owl numbers on a third site within a national park had 

increased. The mixed results highlight the challenges 

of using a single species to evaluate or formulate land 

management plans, while shedding some light on 

potential implications of land management strategies.

Principal investigator: John Keane

Steady tune

Songbird populations have periodic ups and downs, but long-term stability

Long-term research into population trends of 35 

woodland bird species has found that while some 

species are experiencing sustained growth or decline, 

the majority have maintained stable populations despite 

temporary dips or rises. Using 27 years of data, PSW 

scientists tracked bird populations within the San 

Joaquin Experimental Range in the Sierra Nevada 

foothills. Long-term monitoring provides valuable 

insights into population dynamics and can help put 

short-term observations into better context. For example, an observed 3- or 5-year decline in a species could 

merely be the result of a short-term disturbance. Or, if 

that decline fits within a long-term decline spanning 

20 to 30 years, it could indicate the need for concerted 

conservation efforts. The long-range stability exhibited 

by the majority of species monitored also showed that 

species can persist even after a series of bad years.

Principal investigator: Kathryn Purcell

Field studies tracking spotted owl populations have found the bird’s 

numbers increasing in some areas, decreasing in others.

Woodland song birds, such as the western scrub-jay, have periodic 

shifts in population, but overall they exhibit long-term stability. 

Gary Woods

Janice Reid

Climate comforts

Ponderosa pines thrive when planted in climates 

matching their original seed source

More than elevation or geography, transplanting a 

seedling of a ponderosa pine (Pinus ponderosa) to an 

area matching the climate of its seed source best 

determines how well it will grow. Since 1976, PSW 

researchers have been monitoring the growth of 

ponderosa pines in three gardens across California. 

Although they did find that trees grown from seeds 

collected at lower elevations grew taller than trees 

from higher elevation seed sources, matching the 

climate from a pine’s seed source to its transplant 

location produced the best growth results across all 

conditions. Knowing which conditions best promote 

tree growth can help land managers more selectively 

choose seeds for reforestation efforts. Principal investigator: Jessica Wright

Sturdy soil

Soil function, quality resilient to damage from logging

PSW researchers, along with a consortium of U.S. and 

Canadian scientists, have been tracking the short- and 

long-term responses of soils to disturbance. Twenty 

years after logging, across more than 60 study sites, 

affected soils showed little to no difference compared 

to tracts of land without any disturbances. Bacterial 

and fungal diversity remained robust in soils compacted or experiencing partial or complete loss of nutrientrich top cover resulting from logging operations. 

Roots also continued to grow amid compacted soil. 

Only the complete removal of surface materials 

caused a momentary dip in microbial diversity, which 

was attributed to a change in surface temperature and 

exposure to moisture. Understanding effects below the 

surface can help land managers better evaluate the 

ramifications of actions above it. 

Principal investigator: Matt Busse

Ponderosa pine seedlings grew best when planted at elevations 

similar to where they were first collected as seeds.

Despite growing in soil compacted 

by logging equipment, tree roots 

showed little difference 20 years 

after disturbance to roots of trees 

in areas not affected by logging.

Long-Range Research
Urban Ecosystems and Social Dynamics 

Damages, not dollars

Fuel treatments reduce property loss to wildfires, not suppression costs

In a study of wildfires across the country, PSW 

researchers discovered that fuel reduction treatments, such as prescribed burning or mechanically 

thinning forest densities and underbrush, were 

largely ineffective at reducing the cost of suppression efforts when wildfires did occur. Only in 

California did mechanical treatments result in such 

savings. However, all areas receiving prescribed 

fire treatments sustained fewer losses of public 

property, building structures, or residences from 

wildfires than areas left untreated or treated with 

only mechanical methods. Although both treatment 

mechanisms have their merits, information about 

how these treatments related to suppression costs 

allows for a more comprehensive cost-benefit 

analysis of treatment options. 

Principal investigator: José Sánchez

Prescribed burning, or the intentional burning of landscapes under controlled conditions to reducing future wildfire severity, did not appear to reduce suppression costs when wildfires occurred, but did reduce the loss of public property and buildings.

Lance Cheung

Paying for prevention

Ethnicity, perceived risk plays role in willingness to pay for wildfire risk reduction programs

PSW researchers found that a citizen’s willingness to 

pay for wildfire risk reduction seems to be influenced 

not only by one’s personal experience with wildfires 

or sense of imminent risk, but also their ethnicity. 

Among Florida minority homeowners, AfricanAmericans were twice as willing to pay for activities 

that reduce the risk of fire occurrence than their 

Hispanic counterparts. Both groups expressed willingness to pay for programs administered by public 

agencies, but when it came to sharing funds with 

private citizens, most agreed that funds should go to 

homeowners in areas the owners perceived to be at 

high risk. As populations push further into natural 

areas—especially in Western states—thereby exposing themselves and their property to greater risk of 

wildfire losses, communities must grapple with ways 

to fund needed prevention measures.

Understanding these influences can give land managers a framework to approach communities when 

seeking public funds for risk-reduction programs.

Principal investigator: Armando González-Cabán

Streets lined with gold

California “street trees” valued at $1 billion

Trees lining California’s streets and boulevards are 

immensely valuable to communities—to the tune of 

$1 billion. PSW researchers used tree inventories 

from 49 cities across the Golden State and analyzed 

them in i-Tree, a computerized tree inventory and 

management tool, to create a composite picture of not 

only the number of California’s street trees, but also 

their species, size, location, and associated benefits. 

Researchers found that street trees bolstered property 

values by $840 million, while also saving energy by 

reducing heating and cooling needs ($100 million 

value), intercepting rainfall ($40 million value), 

removing air pollutants ($20 million value), and 

storing carbon ($10 million value). In fact, for every 

$1 invested in street trees, communities receive nearly $6 worth of 

benefits. Despite the number of 

California’s street trees growing 

from 6 million in 1988 to 9 million 

today, tree density has actually 

fallen from 105 to 75 trees per 

mile, nearly a 30-percent drop. 

Spatial analysis indicates that 

California cities have room to 

accommodate 16 million more 

trees along their roadways.

Principal investigator: Greg McPherson

The ecological benefits provided by the trees lining California’s streets and boulevards are valued at $1 billion.

Removing or reducing the amount of trees and brush around 

communities is one way to reduce wildfire risk to homeowners.

Urban Ecosystems and Social Dynamics Program
Institute of Pacific Islands Forestry

If the well runs dry

Computer modeling predicts climate change, invasive 

plants could cut Hawaii’s fresh water supply in half

Using computer models to simulate water yield from 

91 stream basins on Hawai‘i Island (the Big Island), 

PSW researchers calculated the effects of projected 

climate change and invasive species growth. They 

found that stream flows could be reduced by as 

much as 50 percent from predicted drier climates, 

while invasive species could potentially siphon off 

an additional 2 percent. Tropical island watersheds 

are not like the slow rivers that flow across the flat 

plains of the continental United States. Instead, 

streams plunge quickly down steep montane forests 

from their headwaters to the coast, making flows 

erratic in their response to rainfall. These projections 

can help communities prepare contingencies for 

potential shortages in water supply.

Principal investigator: Christian Giardina

Tracking a killer

Hawaiian forests stalked by lethal disease

PSW researchers are studying the spread and transmission of a deadly fungus that kills up to 90 percent 

of the native ‘ohi’a trees it infects. Since its first 

outbreak in 2014, Rapid ‘Ohi’a Death (Ceratocystis 

fimbiata) has infected almost 80 square miles on the 

Big Island. Abundant across the archipelago, ‘ohi’a 

trees are the only native trees in Hawaii that colonize 

lava flows. They provide habitat for several rare 

species of native birds and insects and are woven into 

Hawaiian culture through stories and songs. PSW 

researchers are working with a multi-agency science 

team to better understand Rapid ‘Ohi’a Death’s pathology and keep it from leaving the Big Island. 

Principal investigator: Flint Hughes

Invasive strawberry guava trees and ginger plants are reducing the amount of freshwater on Hawai‘i Island, but not to the extent that projected drier climates are expected to have.

Flowers from strangers

Non-native insects serve as primary pollinators 

for eight native Hawaiian plants

PSW researchers are studying the interactions between 

invasive predators, native and non-native pollinators 

alike, and the native plants vying for their attention to 

determine how these relationships are affecting plant 

reproduction. Of the eight plant species studied, most 

were visited most frequently by non-native pollinators, 

particularly the non-native European honeybee, Apis 

mellifera. Among the endangered plants within the 

study group, all were visited less frequently than their 

non-endangered counterparts, while the endangered 

mint, Stenogyne angustifolia, was visited least of all 

and by only one species, a non-native solitary bee. As 

non-native species become established in isolated 

ecosystems, such as tropical archipelagoes, it’s important for land managers to understand how these new 

residents affect critical ecological processes. 

Principal investigator: Christina Liang

Rising to the occasion

Mangrove forests maintaining pace with rising sea levels

The majority of mangrove forests surveyed by PSW 

researchers are keeping pace with rising sea levels. 

Sediment deposited by rivers and near shore waters 

appears to be the primary reason the mangroves are able 

to accomplish this. Mangrove forests play an important 

role in mitigating climate change through carbon 

sequestration. One threat to the movement of sediment 

into mangrove forests is dams, often built to meet 

energy demands within developing countries. Dams can 

significantly reduce suspended sediment in rivers and 

negatively affect mangrove resilience to rising sea 

levels. Monitoring sediment loads and accumulation can 

help land managers know if additional restoration 

activities are needed to help mangrove forests.

Principal investigator: Rich MacKenzie

Sediment samples are extracted from a restored mangrove forest in Vietnam. 

The accumulation of sediment is helping mangroves keep pace with rising sea levels.

Apis mellifera, a honeybee not native to Hawaii, was the most frequent pollinator of native Hawaiian plants in a recent study.

Institute of Pacific Islands Forestry
Principal investigator: Kathleen Matthews 

The bigger picture

Fuel treatment disturbances absorbed by surrounding landscape

Northern flying squirrel populations don’t diminish 

during logging operations to thin dense forests. 

Instead, they move to undisturbed neighboring habitat. 

PSW research showed that when broadening the scale 

of analysis, the animals suffered no decline in overall 

density. Although previous research showed that 

squirrel densities declined in areas where trees were 

removed, these new findings highlight the importance 

of incorporating a broader landscape context when 

evaluating effects of forest management on wildlife.

Principal investigator: 

Angela White

Traveling trouble

Deposited air pollutants carried downstream to poison estuaries

Prevailing westerly winds transport much of 

California’s coastline auto emissions and air pollutants 

high into the Sierra Nevada, but the journey doesn’t end 

there. PSW researchers found that as the pollutants 

deposit themselves across high-elevation landscapes, 

rain, wind and melting snow eventually concentrate the 

chemical compositions into headwater streams. From 

there, they are carried up to 100 miles or more back to 

their origins and pooled within coastal estuaries. 

Estuaries often serve as a transition area for younger 

organisms to mature into the seafaring phase of their 

life cycle. Excess nitrogen in these pollutants can lead to 

algal blooms that can kill many young species in these 

important coastal staging areas. The findings answer a 

question long puzzling the Southern California Coastal 

Waters Research Program, which has tracked nitrogen 

concentrations in estuaries for years and was unable to 

account for this “missing source” of pollution. 

Principal investigator: Pamela Padgett

Going with the flow

Steelhead remarkably resilient to debris flows

Toppled trees and landslides tumbling into streams 

seemed to have few ill effects on juvenile steelhead. In 

fact, the species seemed to thrive from the disturbances. For three years, PSW researchers studied steelhead 

in six streams in northern California, some affected 

by debris flows and others not. They observed similar 

densities of steelhead in the two sets of streams at the 

end of the study. They also found rapid growth by 

steelhead in streams with debris flows immediately 

after the events. Scientists believe that reduced stream 

shading after the debris flow increased stream productivity that contributed to favorable conditions for fish, 

as did the fact that stream habitat complexity was not 

Northern flying squirrels might vacate areas close 

to logging operations, but they don’t go far. 

Population densities didn’t diminish for the 

species when the scale of analysis was broadened. 

John McMillan

Conservation of Biodiversity

Conservation of 

Biodiversity

The key to the code

Genomic mapping opens door for advanced 

bioenergy research

PSW researchers have successfully sequenced the 

genomes of a large population of poplar trees with 

genetic compositions that affect attributes beneficial 

to bioenergy production. This sequencing identifies 

genetic variations correlated to specific traits pertinent to tree growth and biomass properties. It is the 

first functional genomics resource for a forest tree 

species, allowing for a better understanding of the 

regulation of complex traits such as size and volume, 

wood properties, and drought resistance to enhance 

bioenergy production. 

Principal investigator: Andrew Groover

In hot water

Restoring or protecting streamside vegetation can keep 

water cooler for trout

Land use that reduces vegetation along streams and 

rivers can threaten fish sensitive to water temperatures, 

such as California’s golden trout. For six years, PSW and 

University of California–Berkeley researchers measured 

mountain stream temperatures while studying streamside vegetation. They found that areas where cattle graze 

typically had reduced streamside vegetation and warmer 

water temperatures, even to the point of being lethal to 

trout, despite having other in-stream conditions that are 

ideal for habitat. Water temperatures were cooler in areas 

without grazing, which had taller and denser streamside 

vegetation. One of the concerns with warming climate 

trends is warmer stream temperature. Enhancing and 

protecting streamside vegetation may ensure that steams 

have the resiliency to withstand warmer conditions in 

the future and provide refuge for fish.

Vegetation along stream banks helped keep water temperatures cooler, 

a benefit to many aquatic species, such as California’s golden trout.

Poplar trees’ fast growth rates make them a popular resources for 

bioenergy production. 
Partnerships in Action

Nature and nurture

Restoring black oaks sustains environmental and cultural values

PSW scientists, along with a team of 

federal researchers and tribal members, 

produced a report to guide restoration 

of degraded stands of California black 

oak. These acorn-bearing trees provide 

a treasured food for many American 

Indians, as well as forage and habitat 

for numerous wildlife species, but they 

are threatened by high-intensity 

wildfires and encroachment of shadetolerant conifer species. The report 

discusses how intensive thinning and 

fire treatments that benefit black oaks 

can fit within a larger landscape 

strategy designed to increase forest 

resilience to wildfire and drought. 

Principal investigator: Jonathan Long 

Planting problems

Infected nursery stock introducing foreign diseases into native restoration sites

In the past several years, more than 

40 species of the foreign pathogen 

Phytophthora have been found in 

California nurseries specializing in 

native plants, and subsequently in the 

restoration sites where these plants 

were used. PSW researchers and more 

than 50 partners are attempting to nip 

the problem in the bud by creating 

educational materials (http://www.

calphytos.org) and a voluntary 

accreditation program to help 

nurseries adopt practices scientifically proven to reduce the spread of 

disease. Introducing pathogens into 

restoration sites is particularly 

insidious because it often puts rare 

native plants directly in harm’s way. 

One strain of Phytophthora is responsible for the death of millions of oak 

trees along the Pacific Coast from 

sudden oak death.

Principal investigator: Susan Frankel

Wax on

Analysis of body wax helps researchers nationwide distinguish two similar insect species

Chemical analysis of the surface waxes 

of two closely related insect species 

have provided researchers an accurate 

means to tell the two species apart. 

Polyphagous shot hole borers 

(Euwallacea nr. fornicatus) and tea shot 

hole borers (Euwallacea fornicatus) are 

believed to hail from Asia and are 

nearly identical in appearance. In the 

United States, they have caused considerable damage to ornamental and native 

hardwood trees and agricultural tree 

crops such as almonds, avocados, and 

oranges. A network of entomologists 

are using the new knowledge to better 

track the beetles’ movements, while 

also helping land managers tailor 

control measures specific to the species 

they are encountering.

Principal investigator: Steve Seybold

Reconnecting the past

Student collaboration guides land management within tribal history

The Yurok Tribe and Pacific 

Southwest Research Station worked 

with a college student to identify the 

historical range of native prairies 

within the reservation before fire 

suppression and shifts in land management forested the landscape. The 

student, a Yurok tribal member and 

part of an American Indian–Alaska 

Native undergraduate research 

program at Humboldt State 

University, sampled soils and vegetation to determine the boundary of 

historical grasslands and estimate the 

degree of forest encroachment. The 

research supports the Yurok Tribe’s 

effort to quantify and map land 

changes while reintroducing tribal 

burning practices and other restoration activities to reestablish a landscape that supports tribal uses for 

wildlife, forage, and craftsmanship.

Principal investigator: Frank Lake

California black oaks provide forage and habitat to wildlife and also hold cultural importance to Native peoples.

Shot hole borers are highly destructive when they lay egg galleries 

within the bark of trees, such as the California sycamore.

Humboldt State University student and Yurok tribal member Eldon Kinney 

(right) conducts a field sample of encroaching trees and shrubs with Yurok 

Tribe GIS specialist Shaonna Chase and PSW research ecologist Frank Lake.

Partners in Action and Awards

For the birds

High school students learn how to band birds, design research project

High school students from the Center 

for Advanced Research and Technology assisted PSW researchers with 

a bird-banding project at the San 

Joaquin Experimental Range. After 

researchers taught the students how to 

capture birds using mist nets, band 

them, and record physical data, the 

students then developed a research 

project to determine whether a bird’s 

foraging habits were connected to 

where in the mist nets they were 

captured. They found that birds that 

gleaned food from the ground were 

more often caught lower in the mist 

nets, compared to species that foraged 

in trees. The Center for Advanced 

Research and Technology provides 

advanced half-day classes in careerspecific laboratory settings to upperclassmen in the Clovis and Fresno 

Unified School Districts.

Principal investigator: Kathryn Purcell

Urban sustainability

L.A. Urban Center uniting partners, connecting communities to nature

PSW scientists participated in several 

programs this year that brought 

together partners, as well as fostered 

stewardship within urban populations, through the Los Angeles 

Center for Urban Natural Resources 

Sustainability. They shared research 

on climate-resilient trees during the 

“Power of Trees” meeting with the 

California Urban Forest Council and 

California ReLeaf. They also participated in a panel discussion with other 

science organizations to discuss 

research projects and how groups 

could combine resources and efforts. 

Collaborative efforts are geared 

toward connecting urban populations 

with nature and fostering an environmental ethic. 

Principal investigator: Pat Winter

Awards

Volunteer program recognized for diversity

When it comes to restoring native ecosystems, 

the Pu’u Wa’awa’a Dry Forest Unit of the 

Hawaii Experimental Forest doesn’t act as an 

island. For collaborating with 31 organizations 

to restore 39,000 acres, PSW and its partner, 

the Hawaii Department of Land and Natural 

Resources’ Division of Forestry and Wildlife, 

earned the Forest Service Chief’s Volunteers 

and Service Cultural Diversity Award. Local 

schools, scout troops, youth corps, cultural 

practitioners, and even a housing consortium 

combined to design and implement service 

learning opportunities for students that 

connected their culture with their stewardship. 

The award recognized special efforts to 

coordinate with underrepresented communities 

to promote conservation and awareness.

Scientist recognized by plant health 

diagnostic network

Pacific Southwest Research Station plant 

pathologist Susan Frankel was awarded an 

Outstanding TEAM Service Award at the 

National Plant Diagnostic Network 

Conference, held March 8–12 in Washington, 

D.C. The award recognizes public interagency 

and private sector coordination for a cooperative, rapid response to a new wildland 

pathogen, Phytophthora tentaculata. One 

aspect of the station’s invasive species 

research strategy aims to proactively identify 

non-native and native organisms that pose a 

threat to California and Pacific Island 

ecosystems through potential introductions.

PSW Station Director’s Honor Awards

PSW presented its third annual Station 

Director’s Honor Awards in recognition of 

outstanding achievements by station employees. Award recipients were:

Distinguished Science

Connie Millar, a senior research ecologist, 

was recognized for her leadership and 

exceptional scientific productivity, particularly in the field of climate change and 

adaptation strategies. Millar was recently 

named a senior scientist by the U.S. Forest 

Service, the highest designation bestowed 

upon a researcher employed by the agency. 

Science Delivery

Flint Hughes, a research ecologist located at 

PSW–Hilo, was recognized for his ability to 

communicate his research on the effects of 

wildfires, control of non-native species, and 

containment of forest pathogens to help guide 

natural resource policy in affected areas. 

Safe and Healthy Workplace

The PSW–Riverside Safety Committee was 

recognized for its efforts in coordinating a 

highly engaging “Safety Week.” Activities 

included guest speakers, movies, training, 

and group activities to address identified 

areas of concern.

Civil Rights

Pat Winter, a research social scientist located 

at PSW–Riverside, was recognized for her 

dedication and support of the Los Angeles 

Center for Urban Natural Resources 

Sustainability. She has helped facilitate 

networking among urban partners and pooling 

of resources, as well as furthering efforts to 

connect youth to the natural environment.

Innovation and Service

Ann Lindberg, an administrative support 

assistant located at PSW–Davis, was recognized for her exceptional customer service and 

skill helping new and seasonal employees 

navigate the federal hiring system. Her work 

allows new scientists and support staff to 

seamlessly enter the agency and assume their 

duties furthering forest research.

Volunteers replant native vegetation within the Pu‘u Wa‘awa‘a Dry Forest.

2016 Station Director’s Award winners (left to right): Ann Lindberg, Flint 

Hughes, Station Director Alex Friend, Connie Millar, Josh Wilson on 

behalf of the PSW-Riverside Safety Committee, and Pat Winter.

California ReLeaf representative Cindy Blain (left), PSW urban ecologist 

Natalie van Doorn, and CAL FIRE urban forester John Melvin prepare to plant 

a tree during a spring partners’ meeting focused on tree planting and care 

during severe drought.
STATION DIRECTOR

Dr. Alexander L. Friend

(510) 883-8832

afriend@fs.fed.us

ASSISTANT DIRECTOR, RESEARCH

Dr. Jane L. Hayes

(510) 883-8835

jlhayes@fs.fed.us

ASSISTANT DIRECTOR, BUSINESS 

OPERATIONS

Colleen Schneider

(510) 883-8834

ckschneider@fs.fed.us

DIRECTOR OF COMMUNICATIONS

Sherri Eng

(510) 883-8862

sleng@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

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 Locations

April 2017

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

USDA is an equal opportunity provider, employer, and lender.

CREDITS

Director of Communications—Sherri Eng

Writer—Paul Meznarich

Graphic design—Jason Blake

DIRECTOR OF THE INSTITUTE OF 

PACIFIC ISLANDS FORESTRY

Dr. Ricardo D. Lopez

(808) 854-2601

rdlopez@fs.fed.us