Upland Tundra

Climate

Cold winter temperatures and cool summer temperatures, resulting in an annual mean temperature of -2.8°C (27°F), characterize the upland tundra, also known as alpine tundra. These conditions, coupled with low precipitation levels with an annual mean of 324.6 mm (12.8 in.) and a near constant wind, have a dramatic effect on vegetative growth (Western Regional Climate Center, n.d.) . The highest period of precipitation occurs in the summer when mean temperatures exceed 19°C (66.2°F). This allows for surface soils to thaw, enabling limited plant growth. Plant growth affects soil formation when plants hold and stabilize soil in place. Most of the plant biomass is contained in the roots. Dead plants also decompose, forming the organic matter in soil and provide vital soil nutrients to numerous organisms. Plant decomposition is, however, significantly retarded by the cold temperatures, which lock up the water supply in snow or ice and stop or slow the chemical and biological aspects of soil formation.

Soils

Soils of the upland tundra vary greatly based on their specific location.  They are generally shallow, not well developed, and consist of bedrocks interspersed between the bare rocks and rubbles.  Upland tundra soils are from the soil order Gelisols which is made up of three suborders (i.e., Histels, Turbels, and Orthels) (Brady and Weil, 2008). Gelisols is derived from the Greek word gelid which means very cold (Brady and Weil, 2004). A permafrost layer is the "principle defining feature" of this soil type (Brady and Weil, 2008).  This is very fitting considering Gelisols have permafrost with in two meters of the surface (University of Idaho (a), n.d.).  Histels are the first of the three suborders and they have large quantities of organic matter in them (University of Idaho (b)).   These soils accumulate large quantities of organic matter because decomposition of organic matter, a process carried out by chemical and biological activity, is greatly reduced under low temperature and moisture conditions.  Upland tundra is characterized  as having frozen water in its soil for a large part of the year.  While the shallow grade mineral soils in the tundra (slopes of 8 to 10%) are dominantly gray to grayish brown and slightly mottled, upland tundra displays a more oxidized soil, and more streaks and smears of color, of mottle. Histosols, soil that contains more than 20% organic matter, can occur in the tundra environment (Arizona State University, n.d.).  Turbels are the second suborder and they show evidence of extensive mixing by frost action, which is called cryoturbation . Cryoturbation moves soil material resulting in broken and convoluted soil horizon (Brady and Weil, 2004). Cryoturbation tends to mix of bury surface material (containing organic materials) with mineral material laid down on ancient flood plains or lake thaws. Some of the ground movement described includes formation of Pingos, frost boils, bumpy ground, polygons, and stripes. When water is trapped under the re-freezing of the permafrost, a pingo, or random hill is formed. As the frozen, underground water builds on its self year after year, the pingo may grow up to about 50 meters tall. Frost boils, or rock rings form when water freezes and thaws year after year. The growing ice pushes rocks out to its perimeter, therefore marking the active layer of the soil. Frost heaves resulting in bumps along the soil horizon are very common. Some factors affecting severity and recurrence of the heaves include plant cover, rocks, or lakes and small ponds. One of the more interesting phenomena found in the upland tundra soils include the formation of soil polygons. Polygons are formed when water is trapped and expands in cracks in the soil, resulting in geometric shapes between 3 and 30 meters wide. Stripes in the soil horizon are formed by the resorting of particle sizes due to the constant thawing and re-freezing of the soil. The third and final suborder of Gelisols, Orthels, is made up of all other Gelisols that do not meet the criteria of Histels or Turbels (University of Idaho (b), n.d.).  Gelisols present humans with a wide array of construction challenges. Many of the Histels are wet and do not provide enough bearing strength to support roadways or building foundations (Brady and Weil, 2004).   Under conditions when permafrost of a construction site thaws, subsidence often occurs, which can and does cause  structures to shift. Soil texture and structure are both contributing factors in soil moisture.  Most Alaska soils are prismatic which also aids in soil moisture infiltration rates.  Volumetric soil moisture is one way we can tell how much soil moisture is in a soil.  By measuring volumetric soil moisture and other factors; Lynch et al (1999) used climate change models to predict how vegetation would respond.   Other influential soil properties that were used in determining these models were porosity, saturation, matric potentials, percent silt, sand, clay as well as color of soil which counts for albedo factor and soil temperature.  It was found that soil moisture can’t be measured as an independent variable but needs to be considered at an ecosystem level combined with vegetative measurements when considering climate change and plant reproduction in Alaska tundra systems.  As a result, the melting of permafrost, including ice lenses (areas of pure ice), often result in damage and/or loss of property and vegetation. In 1951, Sigafoos had predicted that as the soil would freeze and thaw there would be an effect on the vegetation of the tundra.  He predicted that this would happen through a freeze/thaw process that would stir and mix surface layers of cold soils known as congeliturbation.  This process would affect plants by burying them in the soil, by damaging roots and stems, and by changing soil-water relationships in areas of horizontal surfaces, slopes, and thaw lake cycles.

Vegetation

As opposed to several other range types, upland tundra is home to no more than 200-300 species of plants (Holechek, 2004). These plants tend to be specialized to survive in the harsh climate. The plants adapted to these conditions are perennial grasses, sedges, forbs, low-growing shrubs, and a substantial amount of lichens and mosses. Many of them are also mat (cushion) plants, and/or develop short hairs (pubescence) covering their stems (Viereck, 1972). The matted plants grow close to the ground, creating their own livable microclimate (National Park Service, n.d.).  Due to low temperatures, permafrost, low bacterial activity, and almost complete lack of invertebrate soil fauna, biological material is decomposed slowly in tundra areas. Nutrients are thus not readily available for new plant growth. The result is low production, slow plant growth, and slow revegetation where vegetation has been damaged or removed (EEA/NPI, 1996).

Far East Geologica Institute suggests on their website that the representative genera in this climate are:

Liches:  Cladonia, Cetraria, Alectoria, Cetrarta, and Parmelia

Mosses:  Selaginella, Aulocomnium, Polytrichum, Rhytidium, Rhacomitrium, and Dicranum

Shrubs:  Betula spp. (birches), Cassiope spp. (mountain heathers), Rhododendron spp., Salix spp. (willows), Empetrum nigrum (crowberry), and Vaccinium uliginosim (blueberries)

Graminoids:  Carex spp. and Luzula spp.

Forbs:  Angelica, Saussurea kitamurna, Saussurea spp., Bistorta vivipara, Aconutum, Dryas octopetala (alpine avens), Polygonum viviparum (alpine bistort), Trifolium pretense (red clover), Lidia obtusiloba (alpine sandwort), Saxifraga virginiensis (saxifrage), Eritrichium nanum (alpine forget- me- not), and Cacalia

Vegetation can be influenced by the depth of snow.  Snow cover provides insulation to the ground.   Deep, late-melting snow-beds are occupied by black alpine sedge communities. Moderate snowbed communities typically contain dwarf shrub heath tundra that is dominated by heathers, mountain heathers, and grouseberry. Shallow snow areas on ridge tops and other exposed sites typically contain communities dominated by white mountain avens, snow willow and moss campion, or kobresia. Diverse, colorful herb meadows occur in moist sites below melting snowbanks or along streams. According to the Heritage Community Foundation (2001), the highest elevation communities are composed mainly of lichens on rocks and shallow soil. 

Perhaps one of the most important organisms inhabiting the harsh upland tundra is the lichen. Lichen consists of a specific alga and fungus which forms a symbiotic relationship that makes them act like a single plant. Most are composed of fungal filaments with green alga or cyanobacterium living between them. (University of California Berkley, n.d.).   Their ability to absorb water and nutrients directly into their cells allow them to survive without a vascular system that includes roots. Lichen take on three distinct forms: crustose (crust like), foliose (leaf like), and fruticose (stalk like). The fruticose lichen, commonly called reindeer lichen, plays an important part in the diet of many tundra herbivores (Radford University, n.d.).  As the common name implies, reindeer lichen is eaten by semi-domesticated reindeer and caribou alike. Lichens are very susecptible to fire.  Studies show that it may take 50 - 120 years, following a fire, for lichens to recover.  Caribou make very little use of lichen stands that are less than 50 years old.  Therefore, it is important for fire managers to consider the dietary needs of caribou in their fire management plans. In 2004, Racine et al described to us the findings for secondary succession in a vegetation community after a fire on a hillside on the Seward Peninsula.  The tundra vegetation described depended on its location on the hillside. After the fire, the first communities established were bryophytes, sedges, and grasses. Twenty to 30 years after the fire they found evergreen and willow (indicating permafrost degradation). Also noted was that there wasn’t any recovery of certain moss or lichens. 

Despite their small size, the plants of the tundra put on a stunning display during the short summer season (see picture below). They also provide nutrients for many upland dwelling animal species. Whether directly (herbivore and omnivore) or indirectly(carnivore), upland animals rely on the hardy vegetation to sustain their populations in this beautiful, yet unforgiving rangeland. 

Animal Adaptations

Current Uses

Despite the miserable weather which frequents Alaska’s upland tundra (MacMillan, 2001), thousands of people choose to recreate in these areas. Many even spend thousands of dollars for the cold, wet experience that awaits the upland tundra hunter.  Through the use of a guide or just a pilot, people from many parts of the world have unparalleled experiences above Alaska’s tree line.

A few thousand nonresident hunters come for the thrill of hunting.  Some hunt the barren ground Caribou (Rangifer tarandus), (Valkenburg, 1999). Numerous other hunters pursue the massive, palmated antlers of the Alaskan Yukon Moose (Alces alces). The more adventurous come for the thrill of hunting some of Alaska’s most feared creatures, the bear. Regardless of which species you choose, the Brown/Grizzly bear (Ursus arctos horribilis) or the Black bear (Ursus americanus) (Johnson, 1996), you will have an unforgettable experience that few people ever experience.

One might ask: what do all these animals find so alluring about this forbidding landscape? The answers are food, comfort and security.The bears are here for the berries and ground squirrels (Spermophilus parryii). Moose like the upland tundra for its lack of trees to interfere with their movements, and the availability of tender browse from the shrubs.  The caribou are here for one of their favorite foods, lichen. All the animals like the cool breeze that helps keep the insects at bay during the summer months. The ability to spot threats at great distances provides an extra measure of security for all the species that frequent here. 

Humans have harvested upland animals for thousands of years and will continue to do so as long as the animals continue to inhabit this treeless environment. Some hunt for the meat to provide for winter stores, while others hunt for the trophies associated with hunts of this magnitude. They are happy to pay large amounts of money to do it, which provides an annual source of income for many people living near the upland tundra.

Future Concerns

The current grazing habits of these magnificent Alaskan animals in such breathtaking country is currently threatened. If global climate change continues, it could threaten not just the animal’s habits, but the very upland tundra habitat they rely on. As temperatures continue to warm, many believe that the trees will advance higher up the mountain sides (Wilmking et al., 2004). Lloyd et al (2003) conducted a permafrost degradation study on woody vegetation. They concluded that with the rise of regional temperature; ground temperatures are also expected to increase.  Along with this increase in temperature scientists are expecting to see a loss of permafrost therefore improving the drainage of water in the soil which will contribute to the expansion of several plant communities especially for those that previously couldn’t thrive in cold poorly drained soils. If this were to happen, several factors would eliminate the upland tundra as we know it. Instead of open spaces there could be stands of forest (Elliott and Baker 2004).

A canopy of trees would have a dramatic impact. No longer could the bears find the copious amounts of blueberries. They simply would not grow as well in the shade of trees. The ground squirrel will be replaced by red squirrels (Tamiasciurus hudsonicus), which climb trees to escape danger. These things alone would leave the bears looking for sustenance in other areas. Bull moose would find it difficult to maneuver their massive antlers, tender from new growth, around the trees. They would experience a decrease in available browse as trees replace shrubs. Caribou would find a decreasing amount of lichen under the canopy of trees. This would force them to search elsewhere for their favorite meal. The open spaces which currently provide for the cool breeze and unlimited view would be replaced by forest.

Again in concern with a trend in global warming, a legitimate worry is the increase of snow cover to upland tundra regions. A change in the duration of snow cover could severely harm the vegetative community, resulting in harm to herbivore populations. In a study done by Scott and Ross on snow cover impact, experimantal plots with extended snow cover experienced a serious degradation of most lichen species, including up to one meter around the plot boundaries. The additional snow contributes to more available moisture for plants, resulting in eventual emergence of more vascular species. In addition to vegetative changes, average soil moisture and temperatures changed in response to the extended snow cover (Scott & Ross 1995).

Even if none of these things forced the wildlife to leave the area, the trees would prohibit man from hunting the area as he has for time immemorial. He could no longer spot game from afar and plan to stalk or intercept it as he does today. This would result in a decrease in hunter success which in turn would reduce the willingness of clients to pay for the hunting opportunities in these, once upland tundra areas. This could have a serious economic impact on urban and rural areas alike, since the urban areas provide en route services.

To make matters worse, the decrease in hunting success could have a far reaching effect on the ability of Alaskans to harvest the 22,000 caribou they currently take as a food source each year, Valkenburg, (1999). Two studies released in 2004 indicate that perhaps the future is not all gloom and doom. Wilmking et al. (2004) reports that under some temperature regimes, growth may actually be reduced in white spruce (Picea glauca (Moench) Voss) . The other 2004 study by Ganache and Payette indicates that upward expansion of the tree line may be delayed due to suppressed height growth of black spruce (Picea mariana). With these new studies, it appears that additional research will be required before we can predict the future of Alaska’s upland tundra and the magnificent hunting opportunities that accompany its wide open spaces.

Another concern in the tundra environment is pollution. There is always the chance of pollution due to mining, the search for and extraction of oil, and air pollution from other regions of the world. Air pollution is a major concern in the all arctic tundra types. According to the  Global Environmetal Outlook-1 by the United Nations Environment Programme, many of the long range pollutants originate from the Commonwealth of Independent States, Europe, Japan, and North America. Some of the long range pollutants are persistent organic pollutants (POPs), heavy metals, radionuclides, and acidifying gases. The transportation of oil, like in the Alaska Pipeline, is a possible concern for the tundra.  A spill is always the biggest risk in transportation of oil; if a spill were to occur it would have a longer time to contaminant the soils because of the remoteness of the pipeline and because colder temperatures allow for a slower decomposition of the hydrocarbons in crude oil.

References

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Brady, N. and R.Weil 2004. Elements of the Nature and Properties of Soils 2nd ed. Pearson / Prentice Hall Upper Saddle River, New Jersey 07458

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Elliott, G. and W. Baker. 2004. Quaking aspen (Populus tremuloides Michx.) at treeline: a century of change in the San Juan Mountains, Colorado, USA. Journal of Biogeography. 31(5):733.

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