FOSS Ecoscenarios: Arctic National Wildlife Refuge
General Information
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INTRODUCTION
Biome: Arctic Tundra
The Arctic National Wildlife Refuge (ANWR) is one of the most wild, undisturbed places on
Earth. Located in the northeast corner of Alaska, the refuge covers 76,890 square kilometers
(km2). To the south is the rugged Brooks Range. To the north, lies the icy Arctic Ocean.
Courtesy of US Fish and Wildlife Service
Looking south to the Brooks Range.
ANWR is an arctic tundra ecosystem. The landscape is covered with low-growing plants over a
layer of permanently frozen soil called permafrost.
A great number of large animals live within ANWR. Huge herds of caribou and muskox roam
the vast plain. During the short and soggy summers, insects flourish. Millions of migratory birds
arrive to eat the insects.
The first steps to federally protect ANWR began in 1960, when a huge part of the refuge was
designated as wilderness. In 1980, the US Congress passed the Alaska National Interest Lands
Conservation Act. The Act doubled the size of the protected area and renamed it the Arctic
National Wildlife Refuge. ANWR is the largest designated wilderness in the National Wildlife
Refuge System. Like all wildlife refuges, ANWR is managed by the US Fish and Wildlife Service.
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In Section 1002 of the Act, Congress authorized that future oil development could be considered
in the northern part of the refuge along the coast. This area is called the “1002 Area.” The 1002
Area covers 6,070 km2 of the coastal plain and is the most active part of the refuge for wildlife.
Ever since ANWR was established, people have debated whether oil and gas drilling should be
allowed in the 1002 Area. Some people want to allow drilling. Some people wonder if the oil is
worth the impact on the ecosystem, especially with the risk of accidents. The 1002 Area is only 3
percent of the refuge, but it contains important habitats for polar bears and millions of migrating
birds. It also includes most of the area where caribou go to raise their young.
ANWR offers many ecosystem services. The most obvious are the natural resources like oil, coal,
and natural gas found beneath Earth’s crust in the 1002 Area and just off the coast in the Arctic
Ocean. Another major service is that the open tundra offers habitat for some of the most diverse
communities of organisms found in the Arctic.
Currently, efforts to extract oil or protect these ecosysten services are in conflict. As oil becomes
an increasingly valuable resource, ANWR is in the spotlight of political debates about oil and gas
drilling. Other areas in Alaska, such as Prudhoe Bay, have already experienced oil drilling.
Courtesy of US Fish and Wildlife Service
Caribou give birth on the coastal plain during summer, most within Area 1002.
Another ecosystem service of this arctic region is in the permafrost. Permafrost can store
significant amounts of carbon in its frozen soil. This process is called carbon sequestration.
Humans are adding extra carbon to the atmosphere in the form of carbon dioxide (CO2) by
burning fuels like wood, coal, oil, and natural gas. Increased CO2 in the atmosphere is one cause
of climate change. Scientists estimate that 14 percent of Earth’s carbon is stored in the permafrost
of the Arctic. This process helps keep the amount of this greenhouse gas from accumulating in the
atmosphere. As temperatures rise and permafrost thaws, additional carbon is released back into the
atmosphere. In addition, rising temperatures are causing the Arctic glacial and sea ice to melt.
Other services include the cultural diversity of Native Alaskans that live in and near ANWR. The
refuge also offers aesthetic and spiritual value for many Americans who may never even visit the
area.
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Ecosystem Services
• Climate Regulation: Arctic tundra regulates the global climate by storing greenhouse gases like
CO2 and methane.
• Cultural diversity and heritage: Alaskan natives depend on meat, woolen fur and hides of
muskoxen and caribou for much of their traditional lifestyle, independence, and survival.
• Habitat refuge: The open space of the tundra offers habitat for maintaining many migrating
populations like birds, caribou and polar bears. ANWR has the most biodiversity of any
protected Arctic area.
• Natural resources: Oil, coal and natural gas can be found beneath Earth’s crust beneath the
Arctic Ocean and in the 1002 Area of the refuge.
• Primary production: While the growing season is short in the Arctic, 24 hours of sunlight in the
summer allows for a major burst of photosynthetic production.
• Spiritual experience: Many people value wilderness, even when they may never visit the refuge.
They also find value in preserving it for future generations.
• Water cycle: Arctic tundra stores freshwater as ice and in the snowpack.
• Water regulation: Arctic tundra in ANWR stores freshwater yearlong as ice and snow.
ABIOTIC DATA
The frigid climate shapes the landscape and the organisms that can survive in ANWR. ANWR is
located far north in the Polar Region of Earth above the Arctic Circle. During the summer,
ANWR is oriented toward the Sun as Earth rotates. This is the land of the midnight sun. Around
the time of the summer solstice in June, the Sun never sets, but its long, slanting rays do little to
heat up the air. Summer air temperatures range from 2 degrees Celsius (°C) to 12°C. The upper
layer of the ground thaws and plant growth occurs. This period of productivity is called the
growing season, and lasts only 50–60 days in ANWR.
Courtesy of US Fish and Wildlife Service
The coastal plain of ANWR is pitted with ponds
during the short summer.
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In contrast, during the winters, the Arctic Circle is oriented away from the Sun as Earth rotates.
Because of this, the Sun doesn't rise during the winter solstice in ANWR. At noon the sky is in
twilight, with the Sun remaining just below the horizon. The average air temperature is -34°C,
but can drop as low as -51°C!
High winds, especially in the winter, can have a major impact on the survival of life in ANWR.
Winds can blow up to 160 km per hour (kph), whipping across the flat landscape and blasting any
exposed plants or animals with small ice crystals.
There is little precipitation in the winter or summer. Average annual precipitation, including
snow, is only 15–25 centimeters (cm) per year.
A stable snowpack can benefit plants and animals because of its insulating qualities. Snow cover
can shelter plants and animals from the strong winds and other disturbances. Small mammals, such
as brown lemmings, make tunnels beneath the snow to stay warmer and avoid predators.
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Data courtesy of Environment Canada, Yukon
Snow that falls in the winter often melts during May.
The ground has two layers: the active layer and the permafrost layer. The active layer is the layer
of soil that freezes and thaws throughout the year. Below the active layer is permafrost, made up
of gravel, frozen groundwater, and finer material. Permafrost is soil that has been frozen (below
0˚C) for more than two years.
The top active layer is made of dead and partially decayed plant material. As snow melts in the
summer, the surface soil becomes waterlogged because water can’t drain through the permafrost
below. The ground surface becomes soggy with standing water and flowing streams. The active
layer can thaw as deep as 45 cm in the summer. The active layer is not considered true soil,
because the plant material decomposes too slowly.
BIOTIC DATA
The coastal plain of the Arctic refuge is a vast treeless landscape covered with low-growing
producers. The frigid cold and deep snow make life in the tundra very difficult. New soil forms
slowly. Biodiversity in arctic tundra is generally low compared to other biomes like tropical rain
forests. Plants and animals reproduce quickly in the short summer.
Arctic tundra has low annual primary productivity. Annual primary productivity is the amount of
energy provided by the producers to the ecosystem each year. The primary productivity in
ANWR is low because of the short growing season.
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Artic tundra ecosystems, like ANWR, have low levels of primary productivity, as compared to
other ecosystems, due to the very short growing season.
Tundra plants have adaptations that help them grow and reproduce during the short growing
season, and survive the long, cold winters covered in snow. Because of the permafrost layer,
plants cannot have deep roots. You won’t find large trees or lush vegetation in ANWR. You will
only find hardy, low-growing plants, like shrubs, sedges, lichens, and mosses that can endure the
strong winds, cold temperatures, and dramatic changes in seasonal soil moisture. Dark green to
red leaves allow plants to absorb more sunlight. Many plants rely on simpler forms of asexual
reproduction, like cloning or budding, instead of flowering or forming seeds.
Important producers include grasses and sedges that form protective clumps. Shrubs like alpine
azalea, arctic willow, and Labrador tea grow shorter than usual due to the harsh conditions.
Reindeer lichen is an important producer in ANWR. Lichen is made up of two different
organisms living together in a symbiotic relationship. A photosynthetic alga lives inside a
protective structure of fungus. The lichen grows in a flat, branching structure and spreads on top
of the soil. Lichen is the major food of caribou, especially during the winter. Caribou use their
antlers and hooves to scrape snow cover away to reach lichen in the winter.
Courtesy of Denali National Park
Reindeer lichens provide food for browsing animals. They
are the primary diet of caribou during the winter.
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ANWR is home to some of the most diverse and spectacular wildlife found in the Arctic. The
Refuge is home to 42 fish species, 37 land mammal species, 8 marine mammal species, and more
than 200 migratory and resident bird species.
Standing water on the summer tundra is an excellent breeding ground for mosquitoes and black
flies. Swarms of these insects feed on the caribou herds. Only the coastal breezes can provide the
caribou with relief from mosquitoes and black flies.
Data courtesy of Environment Canada, Yukon
How does temperature affect mosquitoes that bother the caribou?
Caribou migrate in huge herds over 640 km from their wintering grounds in the Brooks Range
taiga to calving (birthing) grounds in the 1002 Area. They return yearly to the same calving
grounds. During calving, the cows and calves are most vulnerable to predators, like brown bears,
and most sensitive to disturbances, like oil drilling.
Courtesy of US Fish and Wildlife Service
Courtesy of US Fish and Wildlife Service
A caribou makes its way across the
marshy arctic tundra.
A huge herd of caribou migrating across the tundra of the Arctic
National Wildlife Refuge.
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Small rodents, like snowshoe hares and lemmings, are common in ANWR. Their population
sizes are closely linked to the amount of food available and size of predator populations. During
summers when food is abundant, rodent populations grow. Larger populations of rodents support
larger populations of predators, such as brown bears, lynx, and snowy owls. As predator
populations grow, the rodent populations decline. And so the cycle continues.
Muskoxen have roamed in the Arctic since the Ice Age. Similar to the caribou, they breed along
the coastal plain in the short summer when there is abundant food.
Courtesy of US Fish and Wildlife Service
Muskoxen huddle together for protection from predators
and cold weather.
Many species of migratory birds nest on the marshy tundra during the short summer. They leave
in fall and fly south to warmer areas where food remains abundant throughout the winter.
Courtesy of US Fish and Wildlife Service
Many North American birds come from as far south as Central
America to reproduce and raise their young, taking advantage of
the long summer days with ample insects and plants for food.
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Animals that live in ANWR all year have adaptations to help them survive the cold conditions.
Mammals tend to have smaller ears, shorter legs and tails, and larger bodies than their southern
relatives to stay warm. Many mammals also have two kinds of hair: an insulating layer that keeps
warm air close to their bodies and a protective coat that keeps snow and cold air away.
A few animals have two phases of color camouflage: one for summer and one for winter.
Snowshoe hares, least weasels, and arctic foxes have heavier winter fur that is white and helps to
camouflage them in snow. This fur is shed in summer to reveal darker brown fur. Similarly,
willow ptarmigan have white feathers in winter and brown plumage in summer.
Brown bears, wolves, foxes, snowy owls, and weasels are the main predators found in ANWR. A
wolf pack will kill 11–14 caribou each year, usually during the caribou migration or during the
winter. Wolves will rarely attack muskox. Arctic foxes and snowy owls are well-adapted to live in
the cold. They hunt small rodents and feed on abandoned carcasses from other predators. Brown
bears eat caribou calves during the calving season, and rodents, roots, and berries the rest of the
year.
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Version date 12/2015