Bonanza Creek Experimental Forest & Caribou-Poker Creeks Research Watershed
Creek Experimental Forest and Caribou-Poker
Creeks Research Watershed are the only designated forest research
facilities in the true boreal forest zone of the United States.
Both are on Alaska state land, with Forest Service and university
research activities conducted under a long-term lease and cooperative
agreement, respectively. Bonanza Creek, located about 20 km southwest
of Fairbanks, Alaska, was established in 1963 with about 3,360 ha
of upland, interior Alaska boreal forest. In 1969, the forest was
enlarged to 5,053 ha to include representative flood-plain forests
along the Tanana River. Bonanza Creek lies within the Tanana Valley
State Forest, a unit managed by the Alaska Division of Forestry.
It is leased to the USDA Forest Services Pacific Northwest
Research Station for the exclusive purpose of conducting research
in forestry. Bonanza Creek was declared a Long-Term Ecological Research
(LTER) site by the National Science Foundation in 1987.
Caribou-Poker Creeks is a 10,400-ha upland research site located
45 km north of Fairbanks that is dedicated to research into hydrologic
and environmental questions about the discontinuous-permafrost boreal
forest of the Yukon-Tanana Upland of central Alaska. In 1969, a
cooperative agreement signed by the Interagency Technical Committee
for Alaska and the Alaska Department of Natural Resources designated
the basin as the Caribou-Poker Creeks Research Watershed. In 1996,
the Water and Environmental Research Center of the University of
Alaska assumed management of the watershed.
The climate in interior Alaska is strongly continental, with cold
winters and warm, relatively dry summers; it is characterized by
drastic seasonal fluctuation in day length (> 21 hours on June
21 and < 3 hours on December 21). Mean annual temperatures in
the Tanana Valley area average between -2 and -5 °C. July temperatures
average 16.3 °C, whereas in January the average is -23.5 °C.
Periods of extreme cold in the vicinity of -40 to -45 °C can
occur at any time from late November through February. Daily maximum
temperatures occasionally reach 35 to 37 °C in June and July,
often with only modest night cooling because of the persisting daylight.
The growing season is short (100 days or less).
Annual precipitation in interior Alaska is 250 to 500 mm. About
35 percent of this precipitation falls between October and April
as snow. Although precipitation amounts during the growing season
may be low, evaporation rates are also low because of the relatively
short growing season and cool temperatures. Even so, as much as
75 to 100 percent of the summer precipitation
may be lost as evapotranspiration. Snow covers the ground from mid-October
until mid- to late April, and maximum accumulation averages 75 to100
cm. Soil temperatures are consistently low.
In this area of Alaska, soils are uniformly immature and range from
cold poorly drained soils with shallow permafrost to warm well-drained
soils in the uplands that support mature white spruce communities.
Parent material falls into three main categories: (1) bedrock composed
of Precambrian schist, (2) thick loess deposits originating from
glacial periods, and (3) alluvial deposits in flood plains. Slope
and aspect are critical in the formation of permafrost. North-facing
slopes are usually underlain by permafrost, contrasting sharply
with south-Bonanza Creek Experimental Forest/Caribou-Poker Creeks
Research Watershed (Alaska) facing slopes and their warm, well-drained
soils. Poorly drained black spruce flats of interior Alaska are
also largely underlain by permafrost.
The taiga forest of Alaska consists of a mosaic of forest, grassland,
shrubs, bogs, and alpine tundra. The forest is dominated by young
stands in various stages of succession; mature stands more than
200 years old are rare due to frequent fires. In areas relatively
protected from fires, such as the river flood plains, the active
erosion and meandering of the silt-laden, glacially fed rivers results
in the active production of newly vegetated silt bars and the rapid
erosion of older, mature stands.
Upland forest types range from highly productive aspen, paper birch,
and white spruce stands on well-drained, south-facing slopes to
permafrost and moss-dominated black spruce forests of low productivity
on north-facing slopes, lowlands, and lower slopes. Flood plain
forests of balsam poplar and white spruce are productive on recently
formed river alluvium where permafrost is absent, but slow-growing
black spruce and bogs occupy the older terraces that are underlain
Long-Term Data Bases
There are climate data for both Bonanza Creek and Caribou-Poker
Creeks. The Bonanza Creek LTER also has a long-term vegetation data
base. There are data for all LTER successional control sites, including
tree-growth measurements, litter collections, seedfall counts, seedling
establishment; thaw depth (permafrost), and 15- and 30- year records
for thaw depth after fire, as well as archived soil samples and
archived herbarium specimens and snow-course measurements. All data
from the LTER site are cataloged at www.lter.uaf.edu.
Research, Past and Present
Much of the early Forest Service research in Alaska was conducted
by scientists from the Pacific Northwest Forest and Range Experiment
Stations Institute of Northern Forestry (INF). Early research
on white spruce seed production began in 1958 and continued through
1992. From 1957 until 1966, INF personnel conducted destructive
sampling and stem analysis for the development of growth and yield
tables for white spruce, aspen, and birch. Both flood plain and
upland stands within Bonanza Creek were used extensively. Demonstration
plots were established for different silvicultural systems on an
upland white spruce site in 1972, and various aspects of natural
regeneration (including seedfall, seedling survival, density and
growth, nutrient status, and competition) also were evaluated. Sprout
and sap production in birch stands has also been studied. Beginning
in 1962, INF and the University of Alaska cooperated in studies of the
effects of red squirrel foraging on white spruce cone and seed production.
This work was later expanded to include the red squirrel response to
various silvicultural treatments.
Between 1964 and 1967, nutrient relationships in birch and black
spruce stands on north-facing slopes were studied at Bonanza Creek.
This work was expanded to include above- and below-ground biomass
and nutrient cycling in white spruce and birch stands on slopes
of all aspects. Numerous permanent plots have been used to study
species composition, successional relationships, and soil temperature
fluctuations. Research has also focused on the spruce and Ips beetles,
large aspen tortrix, spear-marked black moth, and the larch bud
moth. More recently, Bonanza Creek has been the site of studies of
flood plain soil moisture dynamics and formation of salt crust on
freshly deposited alluvium, forest reestablishment and insect and
disease dynamics following wildfire, and tree-species provenance tests.
Research at Caribou-Poker Creeks in recent years has examined the
performance of electrical resistivity, ground penetrating radar,
and transient electromagnetic surveys to determine subsurface conditions.
Hydrologic monitoring has been essential in developing a computer
model capable of predicting runoff rates and volumes from watersheds
with permafrost distribution ranging from 2 to 53 percent. An experimental
oil spill conducted in the mid-1970s has provided critically valuable data
demonstrating natural degradation processes following oil spills
on thick organic soils and continues to provide information on vegetation
recovery and the natural resilience of subarctic forests.
Major Research Accomplishments and Effects on Management
Research at the Bonanza Creek LTER site has contributed substantively
to understanding the relationship between independent
factors and internal ecosystem dynamics in causing successional change in the boreal
forest of Alaska. Major findings of the program are that species
effects are strong in the boreal forest and successional changes
in species composition are not a simple consequence of changes in
competitive balance but involve species-driven changes in biogeochemistry
and the physical environment. In addition, vertebrate herbivores
are a powerful force driving successional change through their effects
on plant competitive interactions and biogeochemistry and succession
influences exchanges of methane, carbon dioxide, water, and energy
in ways that could affect climate.
At these Alaska sites, collaborators have come from the University
of Alaska- Fairbanks, National Science Foundation's LTER Program,
Alaska Cooperatively Implemented Information Management System,
Water and Environmental Research Center, Cold Regions Research and
Engineering Laboratory, Tanana Chiefs Conference, Alaska Division
of Forestry, Alaska Boreal Forest Council, Alaska Fire Service,
Alaska Department of Fish and Game, Arctic Region Supercomputing
Center, USDI Geological Survey, Fish and Wildlife Service, and Bureau
of Land Management.
Research topics at the Bonanza Creek LTER site vary widely, with
30 principal investigators listed in the current proposal.
Lat. 64° 8' N, long. 148° 0' W (BNEF)
Lat. 65° 16' N, long. 147° 5' W (CPCRW)
Bonanza Creek Experimental Forest
USDA Forest Service
Pacific Northwest Research Station
University of Fairbanks Alaska
P.O. Box 756780
Fairbanks, AK 99775-6780
Tel: (907) 474-5881
1Information has been updated since original publication.