Wooded Tundra

Climate

The Woody Tundra Range type describes a region of the arctic that lies inland from the coastal plain, but is climatically moderated by maritime effects.  In Alaska, the woody tundra range type lies between the high mountains of the Brooks Range at elevations up to 900 meters (about 3000 feet) and latitudes of 69º North and the barren tundra of the North Slope, near sea level.  It also reaches as far south as Unalakleet, latitude 63.5º north, where it abuts the coast.  Temperatures tend to be very cool to cold, ranging from average winter lows of -31ºC (-23.8°F), often lower than -41ºC (-41.8°F), to summer highs reaching 16ºC (60.8°F).  The frost-free season is short, lasting from mid June to late September or early October.  These cold temperatures counteract the humidity of the area.  The woody tundra stands in the rain shadow of the Brooks Range and receives very little precipitation, ranging from an annual average precipitation of 134mm (5.3 in.) at Umiat Station to 330mm (13.0 in.) at Unalakleet.  The precipitation is concentrated mainly in the summer months, increasing in June and reaching a peak late August.  There is usually less than 20mm (0.8 in.) monthly precipitation between November and April.  Winds tend to be persistent, blowing at 50-100 kilometers per hour (about 30-60 mph).

 

Soils

The region of the woody tundra is vast and extremely remote.  Because of this,  few detailed soil studies have been performed.  Much of the soils data available for thisrange type have been extrapolated from very few detailed soil surveys.  Available data sources include the STATSGO vegetative mapping, satellite imagery, and educated guesses. All of the soils in this range type are permafrost soils (Alaska Gazetteer 2000) with continuous permafrost at the northern latitudes and discontinuous permafrost in the coastal, lower latitude regions (Young 1989).  True groundwater does not generally occur in this region of Alaska, however a perched aquifer may occur seasonally in hydrogeologic connection with surface water.  According to the STATSGO data (NRCS 2004), just over 20 per cent of the soils in this range type are rough mountainous lands, with another 11 per cent classified as an additional four types of rough mountainous lands.  All of these soils are Gelisols, which indicates permafrost within 100cm (39.4 in.) of the soil surface, and/or have Gelic material within 100cm of soil surface and permafrost within 200cm (78.7 in.) (USDA soil taxons 2004).  The soils have a suborder of orthel, meaning that they are young soils with little profile development and have no special features (Brady and Weil 2004).  The soils of this region are mostly glacial moraines and fluvial deposit.  

The topography of the woody tundra range type in Alaska includes the foothills of the northern Brooks Range and spans north towards the North Slope.  There are many drainages flowing from the mountains toward the Beaufort Sea, which carve deep and sometimes broad valleys in the mountain slopes. As the land stretches toward the coastal plain and loses elevation, glacial outwash is evident (USDA soil taxons 2004) and the soils become different pergelic classes, pergelic indicating moist, cold, newly formed soils (Brady and Weil 2004).  The pergelic cryaquepts consist of nearly ten per cent of the soils and indicate pergelic soils that experience cryoturbation, or frost churning, are fully saturated, and are either gravely or have some loam material present (NRCS 2004). For the most part, the soils of the woody tundra show very little variation.  The main differences present are due to the extent of erosion: whether the soil is still rocky and high on the mountain slopes or has crumbled and deposited to lower elevations.  The main factor inhibiting the development of these soils is the climatic element of cold temperatures and very little annual precipitation.  Other factors are the inability for organic matter or living organisms to affect much change due to a short frost-free season and the presence of permafrost.  Decaying plant material acts as a nutrient sink. The two major nutrients are nitrogen and phosphorus.  Nitrogen is created by biological fixation, and phosphorus is created by precipitation  (UCMP, Berkley).  Additionally, most tundra soils tend to be acidic (Walker et. al. 2001).  Much attention is being paid to permafrost soils as they are considered to be an indicator of climate change.

 Vegetation

Usually when rangelands are mentioned, people tend to think of the Great Plains and an abundance of grasses.  Amazingly, the woody tundra range type supports a vast wildlife population that can sustain quite well on the vegetation present there.  The woody tundra range is the area where the high alpine tundra of the Brooks Range gives way to the lower elevations, the shrubs, lichen and tussocks of the river drainages, and eventually transforms into the barren tundra of the arctic slope. Because this range type follows the Brooks Range north-facing slope, there is very little southern aspect available.  The lack of solar radiation on the predominantly north-facing slopes, along with the dark arctic winters, cool temperatures, steady dry winds, low precipitation, and young, undeveloped soils, mandates that the vegetation be highly specialized to adapt to these forbidding conditions.

The vegetation of the woody tundra range type consists of lichens (Northern reindeer Lichen, Cladina stelaris L.), tussock grasses (Parnassia palustris L. and Holcus alpinus  Sw.), cotton grasses (Eriophorum callitrix Cham.), low and tall deciduous shrubs (dwarf arctic birch, B. glandulosa L.), and dwarf evergreen shrubs (juniperus communis L.) (geobotony/uaf.edu 2004).  According to Dr. D. A. Walker at the University of Alaska Fairbanks (2004), the hills and slopes of the woody tundra are covered 50 – 100 % with vegetation, mixed with patches of bare soil exposed by cryoturbation.  This cover is achieved with a mixture of low-lying lichens and mosses below with shrub growth above.  Gough et al identify cold, often saturated soils of low nutrient availability and short growing seasons as being negatively correlated with plant species richness at a site; topography, snow cover, snow moisture and soil pH are positively correlated with plant species richness at local and regional scales (2000).

Alaskan woody tundra is analogous to Russian woody tundra due to similarities in temperature and precipitation regimes. In Russian woody tundra, a combination of willow and other shrubs grow together with a moss ground cover.  The shrubs consist of blueberry (Vaccinium caespotosum, L.), cranberry (Vaccinium vitis-edaea, L.), dwarf arctic birch (B. glandulosa, L.), crowberry (Empetrum nigrum, L.), valerian (Valerian bracteosa Britt.) (Anderson 1974), and others, all of which are common in Alaska as well.  The mosses Pleurozium schreberi, Aulacommium turgidum, Campthecium trichoides, and Drepanocladus uncimatus, grow under the shrub stands in the cool soils (Tyrtikov 1976).  Tundra soils have an abundance of microorganisms, predominately bacteria, with a substantial portion consisting of algae.  Aside from the case of mosses and lichens growing under a shrub canopy, the tundra vegetation communities have few layers or only one layer.  (Tundra Biome 1971).  Most of the shrub plants reproduce easily even when heavily stripped of foliage as occurs when moose browse.  The shrubs tend to grow where the soil depth is greatest, usually in the watershed deposit areas.  The lichens and mosses of the woody tundra show heavy degradation from grazing animals (Walker 2004), thus the need for the animals to migrate throughout the year.  Changes in the vegetative communities of the woody tundra have recently been detected, as more shrub species invade the tussock tundra, the cause of which is suspected to be due to global warming (Sturn et. al. 2001).

Animal Adaptations

Most woody tundra animals are active year-round. In order to survive the harsh winters with sub-zero temperatures, they must have some method of regulating the equilibrium between body heat production and heat loss via thermal exchange between the body and the cold environment.  Heat regulation occurs through: 1) heat production, 2) heat loss control, and 3) posture and behavior.

As a means of controlling heat loss, woody tundra animals are equipped with insulated barriers of fur, feathers, and body fat.  These animals also utilize control of circulation, especially to their extremities, and maintain control of evaporative cooling.  Heat production is maintained through the control of basal metabolic rate and other actions such as shivering to increase metabolic heat. 

Animals of the woody tundra have developed unique adaptations to help them survive and raise young in the extreme winters.  For example, caribou have hollow outer hairs that trap heat close to their bodies and musk ox are insulated with a dense under-fur that protects them from experiencing cold even in sub-zero temperatures.  These insulating barriers are put on or shed in layers as the seasonal temperatures change.  Bodies with long ears, legs, and tails lose heat more rapidly than those with shorter limbs, which is why many arctic animals have evolved more compact bodies as a means to conserve heat.   

Ptarmigan, arctic hare, arctic fox, and arctic ermine exhibit a changing of color from brown in the summer and white in the winter as a means of a camouflage mechanism.  In addition to winter concealment, white hair and feathers have a greater insulating value than dark-colored feathers or hair, and the white color also radiates less heat.  

Many woody tundra animals grow slower and reproduce less often than their non-tundra relatives.  Generally, they only reproduce when conditions are favorable.  The availability of food and weather conditions are variable in the woody tundra ecosystem; therefore resulting in opportunism, the ability to regulate growth and reproduction based on environmental conditions.  This capability is a survival adaptation in the woody tundra environment.  Predatory birds such as snowy owls do not nest when lemmings (their main prey) are scarce, and woody tundra-dwelling lake trout may take ten years to reach maturity, compared to six years for those in more southern regions.

Food scarcity in winter induces a range of adaptations varying from hibernation to migration for animals residing in the woody tundra.  Arctic brown bears must obtain enough calories in four months to maintain their body functions during eight months of winter hibernation.  This needed energy is stored as layers of fat.  The arctic ground squirrel usually hibernates in clusters of up to one hundred individuals to communally share a mass body temperature to survive the winter months.  Invertebrates undergo a metabolic change that allows extracellular space to freeze without allowing cell cytoplasm to freeze.  Migratory birds such as the Whimbrel, journey to the woody tundra in the spring to breed, and depart in the fall to escape its severe winters.  Small mammals, such as lemmings, ermine, voles and shrews do not have the ability to hibernate.  Alternatively, they depend on the snow layer to insulate their tunnels and nests from the cold.  In some locations, the snow insulation is so good that woody tundra-dwelling lemmings are able to breed during the winter.

The community energy cycle of the woody tundra is quite complex due to the more abundant variety of local community types and available habitats.  It should be noted that the majority of the animals in the woody tundra are active in both the summer and the winter.  Nevertheless, animls are less active in the winter to conserve energy needed for survival. 

Current Uses

Although it is a remote region, there are a surprising number of land uses currently in the woody tundra region.  Historically, the land was occupied by Inupiat peoples on the coastal plain and a small number of Athabaskan and Nunivit peoples.   The land stretching from the Brooks Range to the coastal plains was mainly used for subsistence hunting. Today, there are several towns and villages in the woody tundra area, most of which are established around the Dalton Highway, with the exception of Umiat and Anatuvuk Pass. This area of Alaska has four primary categories of current uses: subsistence living, industrial development, recreation uses, and research and education.  The Inupiaq of Alaska have traditionally traveled inland to the woody tundra region for hunting of caribou, wolf, musk ox, and grizzly bear, as well as other large and small mammals, migratory birds, and fish. The land provides more than simple tangible resources, though.  It also provides the basis for spirituality, customs, and culture. 

Western industry first moved into the arctic in search of gold and coal, of which little was found.  Later, oil was discovered on the coastal plain, and since the 1970’s, development of the oil resources has expanded rapidly.  As the oil supply on the coast diminishes, exploration moves inland.  Currently there are numerous tests wells located in the woody tundra region (Alaska Department of Natural Resources 2004).  Coal exploration in the Coleville mining district may resume, as there is an estimated 330 billion short tons of high ranking bituminous coal located in the area (AK DNR 2004).   The Red Dog mine on the southern slope of the Brooks Range holds one of the largest zinc reserves in the world, and is an active and expanding mining operation (Erickson 2004).  Large reserves of natural gas are known to exist on the coastal plain, and there is much interest in building a gas pipeline.  The pipeline would be the largest private construction project ever undertaken in North America, costing an estimated $18 billion. This industrial development brings with it the need for airstrips, settlements, and roads (Murkowski 2004).  These infrastructure systems would impact the woody tundra ecosystem.  

Numerous recreational uses exist in the woody tundra such as bird and wildlife viewing and photography, hiking, backpacking and mountaineering, fishing, hunting, canoeing, skiing, dog sledding, eco-tourism and general tourism, wilderness lodges, and air charters and flight seeing.  There are also cultural tours, natural history adventures, wilderness skills training, and educational programs.  There are over fifteen businesses that offer guiding and adventuring services in northern Alaska (AK Wilderness Recreation and Tourism Association 2004).  The ownership of lands associated with Alaska’s woody tundra is split between federal and corporative entities. The 1980 passage of the Alaska National Interest Lands Conservation Act designated the Gates of the Arctic and Kobuk Valley National Parks, the Arctic National Wildlife Reserve, the National Petroleum Reserve – Alaska, and various other holdings such as wild and scenic rivers. The majority of nonfederal  land is owned or managed by various Native Corporations recognized by the Alaska Native Claims Settlement Act. Many people also seek to spend time in the wilderness to provide a relief from busy society and to provide spiritual renewal.  As the famous champion of wilderness Robert Marshall said, “…no comfort, no security, no invention, no brilliant thought which the modern world had to offer could provide half the elation of the days spent in the little-explored, uninhabited world of the arctic wilderness” (Marshall 1970).

The arctic has fast become a vital platform for research in understanding global climate change.  Researchers of various disciplines such as climatologists, biologists, archeologists, glaciologists, chemists, and geologists, to name a few, are visiting the arctic in order to conduct their work.  The University of Alaska operates a research station located at Toolik Lake for the purpose of studying global climate changes.  Various research teams have traveled across the arctic to study and to teach a multitude of topics (Mohrwinkle 2004).  Many of these researchers are drawn to the arctic because of concerns about what the future may hold, and see changes in the arctic as a signal of larger global climate change.

Future Concerns

Extensive studies in the arctic have revealed a warming trend is melting the permafrost.  The melting permafrost may destabilize stored methane, which has been found in the permafrost in continental slope sediments including the woody tundra ecosystem (Bockheim et al. 1999). Since methane is a greenhouse gas, this could produce a potential positive feedback increasing warming effects.  Permafrost also serves as important storage for carbon.  As organic material thaws after thousands of years frozen in place, microbes degrade the material and release carbon dioxide or methane (CH4) as a result. Warming of the tundra tends to promote the loss of the carbon into the atmosphere.  Some evidence has recently been revealed that suggests the tundra system is again acting as a carbon sink due to the capacity for ecosystems to metabolically adjust to long-term changes in climate.  This is a hopeful sign, but the arctic ecosystems are still acting as a net source of CO2 to the atmosphere (Oechel et al. 2000).   

An encroachment of more shrub and tree species into the tundra ecosystem has also been observed, occurring especially in sites where the permafrost has melted and the soil has dried out (Lloyd et al. 2002).  This can have a significant effect on wildlife populations as it presents a shift in food sources and available habitat.  According to a study conducted by Walker et al in 2005, there is an "increase in woody plant dominance in response to experimental warming, especially deciduous shrub cover and height" (Walker et al, 2005).  The study also states that, "a shift from herbaceous to woody tundra will have important consequences for ecosystem processes" (Walker et al, 2005).  The study discusses how taller and thicker shrubs, "will change the surface energy budget, mainly through changes in albedo and increased surface roughness" (Walker et al, 2005).  "The increased height and density of shrubs, graminoids, and forbs resulted in decreased cover of shade-intolerant lichens and bryophytes" (Walker et al, 2005).  This is important because, "The decrease in evenness indicates a change in the dominance structure of the plant communities, where fewer species produce a larger proportion of the cover" (Walker et al, 2005).  So essentially, warming of the tundra contributes to more woody shrubs, which block out some lichen and bryophytes' sunlight.  This leads to a general restructuring of tundra.  Although climate change is of great interest for researchers today, there are many other concerns and problems apparent in the woody tundra ecosystem and region.

For example, the lives of the Inupiaq people have changed dramatically over the last century.  They have suffered great losses from disease, suffered at the hand of abusive government policies and corrupt churches, and have struggled to redefine themselves in the modern world while maintaining their cultural values and traditions.  A deep relationship with the surrounding environment forms the base of their spiritual beliefs.  This foundation is being threatened by the depletion of wildlife populations along with a distinct shift in their values.  The primary community value of acting for common good, replaced with the western individualistic perspective can cause a shift in the treatment of the common property, noticed especially in subsistence hunting.  As individual needs become dominant over the needs of the group, common resources can be abused and over used (Howe 2003).  Native people are also facing the challenge of meshing traditional ways with those of western science, a balance that is difficult to strike. 

Another concern pressing in the woody tundra system is the invasion of non-native species of plants and animals such as Norway rats (Rattus norvegicus) transported in cargo containers (USDA 2003) and many other species emerging as new invaders.   An additional concern for the future to address, is the designated status of the Arctic National Wildlife Refuge (ANWR) and other sensitive arctic lands, some of which lie within the woody tundra ecosystem.   ANWR cannot be designated wilderness due to its use by Native subsistence hunters (Kauffmann 1993).  The area is currently under great pressure from industry to open it for oil exploration and development, and is likely to forever lose its pristine state.  There is much focus on potential negative outcomes, but it is important to remember that the woody tundra region within the arctic is still a magnificent, largely untouched wilderness that holds immeasurable value.  To conclude on a hopeful note, a quote from former President Jimmy Carter, “I hope that all of us can marshal our efforts and inspire American people just to do what’s right…to preserve perhaps the most beautiful place in all the world and that’s the Alaska region.”

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