Partners

Collaboration with the University of Maine is the 

cornerstone of the Forest Service’s research program 

on the PEF. The University Forests Office is responsible 

for management of areas not currently in research, and 

for overseeing administration of the forest. A Research 

Operations Team consisting of Forest Service scientists 

and University faculty coordinates activities and reviews 

proposals for new research installations. In addition, many 

scientists from other agencies and institutions in the U.S. 

and Canada commonly use the PEF for their work. 

Facilities

The Forest Service maintains an office and meteorological 

station on the PEF.

Outcomes

Though studies spanning decades are long-term from a 

human perspective, they represent a small fraction of the 

lifespan of the dominant tree species on the PEF. The verdict 

is still out on which treatments are the most productive or 

sustainable over the long term, but we already know that 

some treatments have undesirable results.

The principal finding of Forest Service research on the 

PEF is that silviculture matters.

To maintain composition and productivity in stands of shadetolerant conifers, managers must retain those species and 

establish regeneration in partial shade. 

If shade-tolerant trees are harvested without considering the 

residual stand or new cohort, conversion to shade-intolerant, 

low-quality trees is likely. 

For more 

information about 

the Penobscot 

Experimental 

Forest

Websites:

http://nrs.fs.fed.us/ef/locations/

me/penobscot/

http://forest.umaine.edu/

penobscot-experimental-forest/ 

Contacts:

Penobscot Experimental Forest 

U.S. Forest Service, Northern 

Research Station, 686 

Government Rd., Bradley, ME 

04411. (207) 866-7255.

Lead Scientist, U.S. Forest 

Service, Northern Research 

Station, 5755 Nutting Hall, 

Orono, ME 04469. 

(207) 581-2794.

University Forests Manager, 

University of Maine, 

School of Forest Resources, 

5755 Nutting Hall, Orono, ME 

04469. (207) 581-2849.

The USDA is an equal opportunity 

provider and employer.

U.S. Forest Service 

Experimental Forest and 

Range Network

Forest Service Research and 

Development (R&D) works at the 

forefront of science to improve the 

health and use of our nation’s forests 

and grasslands. Research has been 

part of the Forest Service mission 

since the agency’s inception. Today, 

Forest Service researchers work in 

a range of biological, physical, and 

social science fields; their research 

covers all 50 states, U.S. territories, 

and commonwealths. The Northern 

Research Station is one of six in 

R&D, and includes 20 states in the 

north-central and northeastern U.S., 

comprising both the most densely 

populated and most heavily forested 

portions of the country. 

The Experimental Forest and 

Range (EFR) network contributes 

importantly to R&D’s research 

infrastructure and is increasingly 

viewed as one of its most valued 

assets. There are currently 22 official 

experimental forests in the Northern 

Research Station, and 80 EFRs 

nationwide. Taken together, these 

sites provide a record of forests 

and forest change that dates back 

more than 100 years. Though initially 

focused on local and regional topics, 

EFRs are becoming increasingly 

networked to address issues of 

national and international concern 

such as climate change, carbon 

sequestration, air and water quality, 

and invasive plants and animals.

Cover photo by U.S. Forest Service.

Penobscot 

Experimental 

Forest

United States 

Department of 

Agriculture

Forest 

Service

NORTHERN RESEARCH STATION 

EXPERIMENTAL FOREST NETWORK

NRS-INF-13-11 

Revised 2017
The Penobscot Experimental Forest (PEF) is located in 

Bradley and Eddington, about 10 miles north of Bangor, 

Maine. This approximately 3,800-acre forest was 

established in 1950 as a site for U.S. Forest Service 

research. For more than 60 years, Forest Service 

scientists have been maintaining a large-scale, longterm silvicultural experiment on the PEF, and have been 

studying the ecology and management of northern conifer 

forests. Numerous partnerships have developed over the 

years, most notably with the University of Maine. Though 

originally owned by forest industry, the property was 

donated to the University of Maine Foundation in 1994 and 

serves as a premier example of research collaboration. 

Findings have long informed regional management and 

policy decisions and have become increasingly relevant 

to national and international concerns. 

Penobscot 

Experimental 

Forest

012 0. 5

Miles

Penobscot Experimental Forest

Penobscot 

Experimental 

Forest

Penobscot

River

Blackman

 Stream

Government

Road

Chemo

Pond

U.S. Forest Service office

Orono

9

178

N

95

Map by U.S. Forest Service.

Photo by U.S. Forest Service.

The PEF is in the Acadian Forest between the eastern broadleaf and 

boreal forests in the northeastern United States and adjacent Canada. 

Common trees include red spruce, balsam fir, eastern hemlock, 

eastern white pine, northern white-cedar, and hardwoods such as 

maples, birches, and aspens.

Stand-replacing natural disturbances are rare and dominant tree 

species are long-lived and shade-tolerant.

The forest is naturally multi-aged with high structural diversity. 

Features

Soils on the PEF are the result of glacial processes and the 

principal parent material is glacial till derived from fine-grained 

sedimentary rock. Low till ridges consist of well drained soils 

including loams, stony loams, and sandy loams, while flat 

areas between ridges are poorly and very poorly drained loams 

and silt loams. Low areas are underlain by lake and marine 

sediments: poorly drained silt and silty clay loams. The climate 

is cool and humid. Mean annual temperature is 44.2 °F, with 

January the coldest (17.4 °F) and July the warmest (68.6 °F). 

Mean annual precipitation is 40 inches, with 42 percent falling 

during the 156-day growing season between May and October. 

The longest-running study on the PEF is an experiment 

covering more than 400 acres. This study consists of a dozen 

treatments representing a range of even- and uneven-aged 

silvicultural and exploitive cutting practices applied to 

replicated stand-level management units (MUs). Each MU 

contains sample plots on which data have been collected 

at intervals since the 1950s. The Forest Service and its 

cooperators have initiated hundreds of other studies, many 

within the long-term experiment, to determine the effects 

of disturbance on the forest ecosystem.

Photo by U.S. Forest Service.

Research

Science Delivery

Though research on the PEF was initiated in cooperation 

with forest industry, users of findings have long included 

forestry practitioners, researchers, students, landowners, 

policy makers, and the public. Research results are 

communicated through forest tours, demonstration areas, 

presentations, and publications. Visitors from as far away 

as Russia regularly travel to the PEF to see side-by-side 

comparisons of outcomes of management alternatives. 

More than 300 scientific publications have been 

produced so far, and much of the Forest Service’s data are 

electronically available to researchers and students.