Brooks-British Range tundra

• Category: Grassland, Tundra, and Human Biomes.
• Geographic Location: North America.
• Summary: The Brooks-British Range tundra is the dividing line between interior Alaska and the Arctic. The region is full of magnificent, majestic, and spectacular mountain ranges, rivers, lakes, meadows, and wildlife.

The Brooks-British Range tundra, located in Alaska and Canada, is the northernmost mountain system of the North American Cordillera. The Brooks Range is considered to be the northern extension of the Rocky Mountains. The Brooks-British Range tundra extends about 60 miles (100 kilometers) from the Chukchi Sea eastward across northern Alaska into northern Yukon, and extends a shorter distance into the Northwest Territories. In Alaska, the Brooks Range separates interior Alaska from the Arctic.

The Brooks-British Range ecoregion is a combination of three large areas, including the Western Brooks; the Eastern Brooks Range/British Range; and the lower area of Anaktuvuk Pass, which divides these mountainous ranges. The Western Range has less rugged mountains compared with the Eastern Brooks Range/British Range. This mountainous belt includes the DeLong, Richardson, and British mountain subranges. The Canadian portion corresponds with the British-Richardson Mountain ecoregion. This area of Alaska has several small, predominantly Native Alaskan villages with a total population of less than 500, including Anaktuvuk (population 249) and Arctic Village (152), as well as the communities of Coldfoot (13), Bettles (43), and Wiseman (21). The Canadian side has no permanent settlements.

Climate and Geography

As a biome, the Brooks-British Range tundra spans 61,600 square miles (159,543 square kilometers). The climate of the region is continental sub-Arctic, with temperature variations corresponding to elevation. This type of climate has long, extremely cold winters and short, cool summers. Because the region is so large and includes various low-lying and mountainous regions, average temperatures vary. The average annual temperature in the Brooks-British mountains is 14 degrees F (minus 10 degrees C). The average winter temperature is minus 13 degrees F (minus 25 degrees C), and the average summer temperature is 44 degrees F (7 degrees C). Downdrafts from the mountain passes coupled with cold temperatures can result in severe wind-chill conditions.

Annual precipitation is 7 to 15 inches (180 to 390 millimeters), with the higher elevations and southern-facing slopes receiving more precipitation. The Brooks Range climate is comparable to an Arctic coastal plain, with increased precipitation occurring on the eastern side and at higher elevations.

The Brooks-British Range tundra has been shaped by the folding and faulting of sedimentary rocks, which created several groups of steep, rugged slopes with deeply dissected mountains and ranges from the Cretaceous Period. The elevation extends from 1,600 feet (488 meters) in low valleys up to Mount Isto or Mount Chamberlin, which reach approximately 9,000 feet (2,743 meters). The overall terrain lies from 2,624 feet (800 meters) in the Baird Mountains to the west to 7,800 feet (2,378 meters) in the central and eastern reaches. Small glaciers are scattered throughout the region at around 6,000 feet (1,829 meters); these are remnants of the Quaternary glaciations. Most of the Canadian region is unglaciated. Continuous deep permafrost dominates the region.

Above the permafrost, the dominant soils in the valleys are made up of glacial till and seasonally flooded sandy loams and the slopes of loose sediment and fragmented bedrock. This tundra is sparsely covered with vegetative material due to poor soil, windy conditions, cold temperatures, and the limited growing season. The Brooks-British Range is a drainage dividing line or continental divide, with the northern areas draining to the Arctic Ocean and the southern areas draining to the North Pacific.

Flora

The Brooks-British Range tundra is characterized by low biotic diversity and simple vegetation structures that can survive in its cold and mountainous terrain. Most vegetation grows in the valleys and on the lower slopes. The vegetation consists of prostrate and hemiprostrate dwarf shrubs such as skeletonleaf willow, white Arctic mountain heather, and bog blueberry, as well as erect dwarf shrubs such as Richardson's willow, grayleaf willow, and Lapland rosebay. Other common types of vegetation in the valleys, scree slopes, and alpine areas include forbs such as large-flowered wintergreen, arctic lupine, and alpine bistort; small awned sedge; purple mountain saxifrage; eight-petal mountain-avens; horsetails; lichens such as Arctic kidney, alpine snow, and globe ball; and mosses including splendid feather, turgid aulacomnium, and dicranum. All vegetation is vulnerable to frost at any time.

The southern slopes harbor black spruce and quaking aspens; this area is considered to be the northernmost limit for these trees. Trees in the subalpine areas include subalpine fir, lodgepole pine, stunted white spruce, and dwarf birch. Other than balsam poplar, very few trees grow on the northern drainage side of the Brooks-British Range tundra.

Fauna

The tundra supports several mammalian species. Porcupines and central and western caribou herds seasonally migrate through the river valleys. Common mammals include moose, mountain goats, and Dall sheep. Predators include brown and black bears, red and Arctic foxes, wolves, wolverines, lynxes, and martens. Smaller mammals include common and dusky shrews, Alaska and hoary marmots, northern red-backed and singing voles, ground squirrels, lemmings, pika, and snowshoe and tundra hares.

Avian species include tundra swans, long-tailed jaegers, rock and willow ptarmigans, northern shrikes, American golden plovers, grebes (horned and red-necked), American pipits, sparrows (savannah and white-crowned), redpolls (common and longspur), and horned larks. Birds of prey here are golden eagles, owls (great horned and snowy), marsh hawks, and gyrfalcons. Other common birds are black-billed magpies, common ravens, gray-cheeked thrushes, and sparrows (American tree, white-crowned, and fox).

The only amphibian is the wood frog. There are no reptiles.

Land Use and Conservation Status

Land use consists mostly of big-game/sport hunting and subsistence use. The area is considered to be relatively stable and intact. The Dalton and Dempster Highways run through the area, as does the Trans-Alaska Pipeline, which parallels the Dalton. Beyond the road systems, disturbance to the area is minimal. Threats to the area are small mining operations and increased numbers of recreational-park users damaging the fragile vegetation.

The Brooks-British Range tundra has several large protected areas. In Canada, protected areas include Ivvavik National Park and Vuntut National Parks. In Alaska, the Noatak basin was first proclaimed a national monument in 1978 and later a national preserve in 1980. The Noatak National Preserve covers 6.5 million acres (2.6 million hectares) and is the largest intact wilderness and watershed in North America. On the border of Noatak National Preserve are Kobuk Valley National Park and Gates of the Arctic National Park. Kobuk Valley National Park is 1.7 million acres (675,749 hectares) and was also established in 1980. Gates of the Arctic National Park is the second-largest national park, at 8.4 million acres (3.4 million hectares); like the Noatak basin, it was proclaimed a national monument in 1978 and a national park in 1980. This park is located entirely in the Arctic Circle.

All the US areas were established under the Alaska National Interest Lands Conservation Act of 1980. Of these three national parks, Noatak is the only one that allows sports hunting.

There are also several federally designated wild and scenic rivers in the Brooks Range.

The two Canadian parks cover only part of the Brooks-British Range tundra's extent in Canada. Ivvavik National Park covers 2.5 million acres (1.0 million hectares) and was established in 1984. It lies on the shores of the Beaufort Sea and is adjacent to the Arctic National Wildlife Refuge. Ivvavik means nursery, and the park was created to protect the caribou herds' calving areas as well as a native land-claims settlement. Established in 1995, Vuntut National Park covers 1.0 million acres (434,500 hectares) and shares parts of its borders with Ivvavik National Park.

It is widely thought that as global warming progresses, it will increase the risk and spread of wildfires in the Brooks-British Range tundra, due to somewhat higher average summer temperatures, increased lightning activity, and drier surface conditions. Broader spread of fire will release more carbon into the atmosphere, a positive feedback effect of the greenhouse gas function. On the ground, fires will alter habitats and thereby put pressure on species to adapt or move. The tundra biome may actually increase in size as forests disrupted by wildfire convert to grasslands. Researchers are making concentrated efforts to better understand the effects of fire in the tundra region to assist with future conservation and managment. One such study, published in March of 2024, examined the biophysical effects of old fires on the region. The insight gained from this and similar studies will help scientist as the area is altered by climate change.

Bibliography

Lange, Otto L., et al. “Upland Tundra in the Foothills of the Brooks Range, Alaska, U.S.A.: Lichen Long-Term Photosynthetic CO₂ Uptake and Net Carbon Gain.” Arctic and Alpine Research, vol. 30, no. 3, 1998.

Miller, Eric A., et al. "Biophysical Effects of an Old Tundra Fire in the Brooks Range Foothills of Northern Alaska, U.S.A." Polar Science, vol. 39, no. 100984, Mar. 2024, doi.org/10.1016/j.polar.2023.100984. Accessed 28 Sept. 2024.

U.S. Forest Service. “Wildland Fire and Climate Change.” June 27, 2011. . Accessed 29 Sep. 2024.

Walker, Marilyn D., et al. “Plant Communities of a Tussock Tundra Landscape in the Brooks Range Foothills, Alaska.” Journal of Vegetation Science, vol. 5, no. 6, 1994.