Barren Tundra

Climate

Barren tundra is characterized by a low mean annual precipitation of 357 mm (14 in.) and low mean annual temperature of  -5 °C (-0.2 °F). Most precipitation occurs from June to September, often peaking in August. Despite low precipitation, permafrost prevents much water from moving into the ground, and low temperatures slow evaporation, often resulting in seasonal wet sites.  The climatic diagram below shows the Tundra Biome annual precipitation (cm) and the the average temperature in dgrees Celsius. After temperature, microtopography, or small variations in ground conditions, is an important factor in predicting vegetation because microtopography affects soil moisture. Low sites are generally wet while high sites are generally dry. Each moisture type supports a different community of vegetation. Although the tundra is usually wet in the summer, water is available only in a frozen form most of the year. As a result, vegetation and lichen present must be drought tolerant. Soils are characterized in this area by the presence of permafrost, decreased decomposition due to low temperatures, and seasonal freezing and thawing that prevents horizon development.     

Soils

According to the USDA's Natural Resources Conservation Service, the majority of soils in Alaska, including tundra soils, are Gelisols. These are typically mineral or organic soils of very cold climates that have permanently-frozen ground, called permafrost occurring within two meters of the ground’s surface.  The word "Gelisol" comes from the Latingelare meaning "to freeze", a reference to the process of cryoturbation. Cryoturbation refers to frost churning, or alternating thawing and freezing events and/or ice segeration in the active layer (seasonal thaw layer) and/or the upper part of the permafrost. Overall, these soils have undeveloped soil horizons due to this thawing and freezing that occurs in the warm season (Smith 2001). Brown and Hinkel (Circumpolar Active Layer Monitoring 2003, online) found the maximum depth that soil thawed over permafrost averaged 55 cm (21.7 in). This thawing “allows root penetration, growth and nutrient uptake by tundra vegetation (Massachusetts Institute of Technology 2004, online).”  As shown on the map below, soils of the tundra regions are dominated by the suborder Turbel with smaller areas of Orthels.  Turbels have one or more soil horizons which are irregular or distorted, caused by the cryoturbation process.   The suborder Orthels are soils which do not show signs of cryoturbation and are generally dryer than Turbels. (USDA NRCS 1999, online). 

Directly above the permafrost layer is a layer of mineral soil followed by organic debris. This organic layer is provided by tundra plants and animals which accumulates into an active layer above the mineral soil. Due to the low temperatures of the region and water logged soils, tundra soils are able to store large amounts of carbon (MacLean 1996, online). This has classified them as one of the top three carbon dioxide sinks on the planet. 

Although Gelisols are the most prominent soil order found in the Barren Tundra, Entisols and Inceptisols are also found. Entisols are very young soils that lack diagnostic horizons. Some have the beginning of horizons starting to form but they are generally very weakly developed and have little evidence of weathering. Inceptisols are also young soils with little development although they generally have more than entisols. Most contain weakly formed B horizons. Both Entisols and Inceptisols are found in a wide variety of habitats around the globe and in multiple climatic conditions (Brady, 2008).

Vegetation

Arctic tundra does not have a unique vegetation type, because “structurally the tundra is a grassland and mixed shrubland" (Smith 2001). Temperature is the most important factor that determines what plants can grow in the Arctic. Secondary factors include soil moisture and soil fertility. “The wetness of the soil is controlled by the microtopography of the land much more than by annual precipitation," because permafrost prevents rain and meltwater from moving into the ground. In addition, evaporation is slowed by low temperatures (Pielou 1994).

In a global context, the Circumpolar Arctic Vegetation Map (CAVM) divided the Arctic into five bioclimate subzones. Alaska's arctic tundra consists of the warmest three. Subzones C and D are barren tundra, whereas Subzone E is somewhat shrubby. In Subzone D, "vascular plants generally cover about 50-80% of the surface," according to the Toolik-Arctic Geopotanical Atlas's (TAGA) website on the project. There are about 125-250 local vascular species in this subzone. The mosses contribute to an organic layer in the soils. This is known as the Betula nana subzone. In Subzone C, consisting of only the northernmost tip of Alaska, there is quite a bit of vegetation, "but vascular plant cover is still open, and interrupted by frost scars and other periglacial features," according to TAGA. Although more diverse than Subzone B, Subzone C only has 75-150 plant species total. Legumes are important on nonacidic substrates, whereas Cassiope species distinguish the subzone and are found on acidic substrates. This is known as theCassiope tetragona zone (CAVM Team. 2003).

In Alaska, low wet areas are dominated by tussock-forming sedges and contain “dwarf heath, and a sphagnum moss complex (Smith 2001).” Additional mosses found on wet soil include AulacomniumDitrichum and Calliergon (Bliss 1988 cited in Hagenstein et al. 2001, online).

Species that appear on well-drained sites include a low shrub -- dwarf arctic birch (Betula nana -- see photo at left)-- and heath shrubs -- crowberry (Empetrum nigrum), narrow-leaf Labrador-tea (Ledum decumbens), mountain-cranberry (Vaccinium vitis-idaea) (USGS 2004, online) (Smith 2001). “Mosses (e.g., Hylocomnium splendens and Sphagnum spp.) and lichens (e.g., Cetraria cucullata, Cladonia spp., and Cladina rangiferina -- see photo below) are common between tussocks (USGS 2004, online).”

The driest sites in this land are usually located in the hills and higher elavations. The surface there is often rocky and exposed to frost action. “Plant cover consists of scattered heaths and mats of mountain avens (Dryas spp.), saxifrages (Saxifragaceae), and other cushion plants….”

Relatively warm south-facing slopes support tall shrubs, grasses and legumes. “Cottongrass (Eriophrum angustifolium) dominates the gentle north-facing and south-facing slopes, reflecting the higher air and soil temperatures and greater snow depth (Smith 2001).”

One common vegetation is Caribou moss (Cladonia rangiferina) which is a very important food source for the migrating caribou herds. Not a moss but a lichen, it can become dormant during the cold months of little sun and little water and then start growing again after many months (Blue Planet Biomes, 2000a).  It provides a large portion of the carbohydrates for the caribou during the cold months (Blue Planet Biomes, 2000a). Caribou can smell it through the snow and dig down through the snow to access it.

Animal Adaptations

The barren tundra supports a variety of wildlife but far less than many other environments due to the harsh climatic conditions. Some of the animals that can be seen in the barren tundra include moose, caribou, muskox, wolves, polar bears, arctic fox,  grizzly bears, snowy owls, and ermine (Blue Planet Biomes, 2000b). Space, water and cover are the major factors that most wildlife depend on which creates certain limiting factors in wildlife. The barren tundra has a vast amount of space for wildlife and large amounts of water in the warmer months. However, during the winter, water is hard to find with snow being the major source for water intake. Cover is also very limited in the tundra which can leave animals exposed both to predators and weather.  Many migratory birds also populate the barren tundra during the warmer summer months when a variety of birds fly north from the "Lower 48". The biggest nemesis of the larger wildlife species are of course the tundra insects.  During summer months, animals are surrounded by clouds of black flies, deer flies, no-see-ums,and of course the infamous mosquito.

Current Uses

Current land uses on the tundra include subsistence hunting, commercial hunting, energy extraction, scientific research, recreation and use by wildlife. The North Slope Borough has a resident population of 7,500 people (Alaska Department of Labor and Workforce Development, 2000) which actively subsistence hunt and recreate in the tundra. Sport harvest and recreation is greatest off of the James Dalton Highway or Haul road which was built for the pipeline and starts by Livingood, Alaska and goes North all the way to Deadhorse. Starting around the truck stop town of Coldfoot, the Dalton Highway corridor begins, which includes a 5 mile non-motorized and bow hunting only are from both sides of the road. One reason for this corridor being put in place was concern for bullet holes in the side of the pipeline which could cost millions of dollars to the oil companies. Also, before the 5 mile corridor was in existence it was a slaughter house for caribou hunters. It was too easy for hunters to harvest caribou because caribou migrate across the road system and people were driving on the fragile tundra biome killing vegetation that took years to grow.  

Rural households are generally very successful at subsistence hunting and harvested goods are generally shared with others in the community. Fish is the main subsistence food in Alaska (Wolfe 1989). However subsistence hunting in Alaska can involve harvesting wildlife such as caribou, moose, whales and waterfowl (Kofinas 1993). Plant products are also gathered and used including a variety of berries (Wolfe 1989). Arctic Village harvests an estimated 521.1 pounds of wild food per person per year, and Kaktovik harvested 885.6 pounds of wild food per person in 1992 (Wolfe 2004). Subsistence hunting has cultural significance in addition to being an important part of the rural economy (Kofinas 1993).

Oil was discovered in Prudhoe Bay in 1968, starting the boom in the oil industry in Alaska. Alaskan employment in the oil industry peaked  at 10,700 people in 1991 but Prudhoe Bay itself still employed 6,063 people in 2002. According to a report by Scott Goldsmith in 2008, 31% or roughly 110,000 jobs in Alaska are supported by the petroleum industry. After the pass of the Alaska Native Claims Settlement Act (1971),  the 789-mile Trans Alaska Pipeline was built (DuFrense 2003).  Today more than 1 million barrels of oil a day are produced from existing oil fields in northern areas of Alaska (U.S. Fish and Wildlife Service, 2001). The Alyeska Pipeline brings in enough money to give every Alaskan Resident a personal fund dividend (PFD), which is upward to a thousand dollars a resident each year.

Future Concerns

Future concerns for the barren tundra include oil development in the Arctic National Wildlife Refuge and the effects of global climate change on the region.  The Alaska National Interest Lands Conservation Act or ANILCA was signed into law in 1980 which doubled the size of the Arctic National Wildlife Range now known as Arctic National Wildlife Refuge. It was quoted during the Eisenhower Administration as being,"One of the world's great wildlife areas. The great diversity of vegetation and topography in this compact area, together with its relatively undisturbed condition, led to its selection as ... one of our remaining wildlife and wilderness frontiers." by Secretary of Interior Frederick Andrew Seaton (U.S. Fish and Wildlife Service, 2001). 

 Proponents of drilling in the Arctic Refuge list some of the following reasons in favor of drilling: 1) Less than 10 % of the refuge would be considered for drilling; 2) Drilling could generate billions of dollars for state and federal treasuries; 3) New jobs in Alaska and in other states would be created (Arctic Power 2004). However, in 1999 two thirds of Americans did not want drilling to occur in the Arctic Refuge. The area under consideration is the calving ground for the Porcupine Caribou Herd, and the coast provides terrestrial denning sites for polar bears (Defenders of Wildlife 2004). Drilling and exploration would also impact other wildlife habitat, permafrost soils, vegetation and contaminate water and soils (U.S. Fish and Wildlife Service, 2001). 

Global climate change is occurring, and the arctic is warming faster than the rest of the earth. Average annual temperatures in the arctic have increased at almost twofold the rate of the rest of the world over the last few decades. The arctic is particularly vulnerable to the impact of climate change. Many coastal villages may face increased erosion as sea level rises and sea ice diminishes.  Arctic transportation, industry and infrastructure will also be impacted by ground thawing creating shorter frozen periods which will reduce the time in which ice and snow enable easier transport over the tundra and its waterways (Hassol 2004). The declining sea ice is also an issue for polar bears which require sea ice to hunt.  They bears smell out their prey, preferably seal, and wait in ambush by their breathing holes in the ice or stalk them while they are out of the water (Polar Bears International, 2010).  With the retreating ice, Polar Bears face increased threats from the loss of habitat. In May 2008, the bear was listed as threatened under the Endangered Species Act and remains so today (Polar Bears International, 2010). 

Temperatures of permafrost have also increased (up to 2°C in some areas) in the last few decades and in many areas the active layer depth is increasing. Tundra soils store a significant amount of the earth’s terrestrial-based carbon. If this carbon is released from the ice and tundra soils due to warming, climate experts say it could increase the rate of global warming by adding large amounts of carbon dioxide back into the atmosphere.

References

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