Table of Contents
Tundra is a Russian term meaning a rolling treeless plain. Colloquially it often is called “the barren lands”. It is treeless but not barren. It is a special landscape with a marvellous seasonal array of natural processes flawlessly executed by a carefully selected diversity of ecosystems.
Tundra extends well south of the arctic circle (60 degrees north latitude) including large areas both west and east of Hudson Bay (Ungava) and the northern quarter of Labrador. About 30 percent of Canada lies north of the treeline and that is where tundra begins. Between the boreal forest and the tundra, the Taiga is the “land of little trees”, the land where trees lose out. Tundra is simply what is able to survive after the trees drop out of the mix. Half of the tundra area is north of 60 on the arctic islands. As you go from the southern tundra to the arctic islands, the number of kinds of plants drops from about 400 to about 501. More and more of the land is without any vegetation.
Cold and wind certainly increase but, more importantly, precipitation decreases until only 10 centimetres may fall in a year. These arctic islands are polar desert where there is too little water and vegetation gradually becomes very sparse as a result.
Stan Rowe, ecologist, philosopher and author wrote to Jeff Amos:
Thanks for sending along the piece “A place of terrible beauty at the tree line’s edge.”
I’ve felt exactly the same way in visiting those remarkable landscapes where the open lichen woodland gives way to the “forest-tundra,” with white spruce strings on the eskers and little patches of black spruce by the margins of lakes in a mosaic of tundra-like patches. The East Arm of Great Slave Lake, the Lockhart River, Artillery Lake and beyond are marvellous places.
Box 11, New Denver, BC, 7 December 2001
Our sample of the tundra comes from the Coppermine valley on the western arctic coast, Bathurst Inlet on the central arctic coast, the Richardson Mountains in the central barrens, the Thelon valley west of Hudson Bay and from northern coastal Labrador.
5 – 5: The tundra of Labrador has many coastal influences including foraging by caribou on seaweeds and overlap of ranges of black and polar bears. (Note caribou stag on right shoreline of Dog Island.)
The area that is now tundra has not always been as it is today. Over geological time, the northern latitudes of our earth have been very dynamic. After a long period under a heavy load of ice, during the recent past, the north has been emerging from under its load. With the weight of the ice gone, the shores have been rising dramatically. The earth’s crust is rebounding all around the polar region.
The dynamics of the north have been more than geological. As the crust rebounded, former coastal habitats, such as marshes and rock pools moved continuously inland, dried out and transformed into other habitats. Crustal rebounding drove their inhabitants to move to keep pace with their moving habitats. Much earlier, even greater changes in habitat took place. Beds of stromatolites fossilized in shoreline cliffs of the Canadian north give evidence of times when our north was much kinder habitat for early organisms. The cyanobacteria (blue-green algae) that produced these stromatolites were the organisms responsible for putting the first oxygen into the earth’s atmosphere.
As the name dictates, tundra is treeless. Why can’t trees grow here? Experiments show that trees can survive temperatures well below the minimum experienced on the tundra. So it is not minimum temperature. Many other plants cover much of the tundra’s surface but no trees. The problem is that trees try to grow too high above the surface and the temperatures up there are 7 or 8 degrees C colder than near the surface of the ground. This means that small plants, close to the ground, have many more hours of temperatures at which the chemistry of “Green Magic” can perk along. Up at tree height, there are not enough hours with high enough temperatures for enough photosynthetic “green magic” production of new tissue to take place. A plant can’t grow tall on the tundra, except in sheltered spots such as the bottoms of steep valleys. This is exactly what hunters look for at nightfall. There will be shelter there, a few black spruce, the most stoic of all trees.
Ecologically, the tundra is a ‘wet desert’. Desert because of the lack of precipitation, not because of heat. Snow can bring 2 to 4 times as much water as rain brings but there is very little snow on the tundra. The tundra environment is limited by receiving only about 100 to 170 millimetres (4 to 7 inches) of total precipitation — rain and snow — for the whole year.
Caribou, muskoxen and others depend on lack of deep snow so that they can dig down through the snow to find forage to carry them through the winter. When there is a ‘weather accident’ such as persistent freezing rain in winter, the snow can become impenetrable ice. In the winter of 1974-5, this happened and 75 % of Canadian muskoxen died of starvation. They were unable to dig through the icy crust. Arctic ground squirrels (called “sic-sic” in imitation of their call) have a different approach. They hibernate and in a region of permafrost where earthen burrows are difficult they need deep snow to provide insulation for their overwintering burrow. They seek out deep drifts in gullies.
The tundra gets equally short rations of heat. Up there, ice and cold are a way of life and everything has adapted to that. The tundra gets from 50% to only 15% as much solar energy as the northern edge of the boreal forest, despite longer days. Not only is the total sun energy limited but also it is supplied over a growing season of only 2 to 4 months. This limits the amount of energy for “green magic” but, equally important, it also speeds up the clock and forces all natural processes to scramble to keep up. This compression of natural processes into the short ‘active’ season causes some wonderfully concentrated displays of natural riches.
Once the sun does return to shine even at midnight, the ground, the surface water and the living things warm up. There is little variation in temperature over 24 hours, sometimes as little as one degree C. Even though the temperature one metre above the ground may still be cool, the temperature at the ground can be several degrees higher.
Some plants have adaptations that raise that important temperature, where the natural processes actually take place, to even higher levels. The petals of Arctic Avens (Dryas integrifolia) form a near-perfect parabola that reflects and focuses the sun’s energy onto the flower’s reproductive parts, thus hurrying the most critical annual process. Some insects have learned of this natural heater and gather around the flowers’ private parts to warm themselves.
Other plants, of several species, such as Diapensia, grow in ‘cushions’, accumulations of both living and dead plant matter in a dome-like shape. This mass of insulating material retains heat that has been absorbed and warms the living parts of the plant to several degrees over the air temperature above.
On the tundra, living things must accomplish their goals in a very short period of warmth and plant production. Some moths going through egg, larval and pupal life stages in order to produce an adult simply can’t do all that in 2 or 3 months at tundra temperatures. Consequently, getting through one life history can take up to 14 years. Even spiders that do not have such a complex life history can take 7 years to mature.
It is easy to see how such a severe environment can exert strong forces that will allow only a few selected species to succeed on the tundra. Most are selected and adapted from species found in the boreal forest region. It’s a tough competition and only a few make it. Of the 3200 species of mammals, only a maximum of 23 succeed beyond the treeline on the North American tundra. Of 8600 species of birds, only 6 or 7 live year-round on the tundra. But another 70 species come for the breeding season. Fortunately, about 400 species of plants, not counting the mosses and lichens, succeed in the southern tundra and provide the “green magic” that supports all else. Of the vast diversity of insects, only about 600 species succeed on the tundra. Some succeed beyond our fondest hopes!
Although the number of tundra species is much smaller than in tropical hotspots of biodiversity, the number of individuals of each kind can be huge. Caribou, mosquitoes and lemmings come to mind. The productivity of animals on the tundra is high in a different way. How high can be judged by the successful presence of carnivores. Arctic wolves have been successfully reproducing their population for a long time despite human depredation on both the wolves and their natural prey species. Snowy owls have had similar success harvesting small mammals, although needing occasional forays south in hard times. Even wolverines have limited success on the tundra by ranging widely and eating anything they can catch.
There are a few tundra specialists. Muskoxen are an outstanding example. Their Latin name, Ovibos (sheep/cow), reflects their similarity to sheep in some ways and to cows in other ways. They are the only survivors of a once large group of ice-age “oxen”. For 150,000 years, the environmental forces of the tundra have selected the features that have enabled muskoxen to survive in this demanding environment. How can we even contemplate allowing the loss of such a being?
Both brown and collared lemmings and polar bears are other examples of tundra (and arctic seas) specialists. Polar bears also exemplify the most important solution to the low ecological productivity of the tundra; link the tundra to the sea. Polar bears discovered the advantages of this important landscape linkage but it also is the key to success in the arctic by the Inuit. Both are now undergoing further adaptation as the access to the sea’s productivity by way of the ice is becoming limited. The Inuit can respond by using boats and increasing their access by water rather than by ice. The bears don’t have this option. They can’t successfully hunt seals in the water. Attempts to hunt by swimming are causing drownings. They need ice. And the sea ice is forming later and melting earlier each year as global climate warming affects the arctic even more than other latitudes. Some polar bears are facing much shorter hunting seasons for lack of ice.
The nature of the ecosystem that all these living beings inhabit can be sketched by looking at the amount of each kind of plant and animal that you find on the ground. Clearly, plants will have the greatest amount of living mass on the ground. Give them a score of one million units of biomass. Compared to that, soil microorganisms come next with 30,000, then insects with 4,200. Plant eaters have 160, insect eaters have 45 and carnivores have 3. Species we consider charismatic are not big parts of the system when viewed in this way.
In the tundra, permafrost is one of the most important forces. The ground is frozen to depths of 250 to 600 metres. Permafrost can be large blocks or lenses of ice. In other soils the ice of permafrost is small crystals evenly distributed through the soil. In summer, as the heat input increases, permafrost melts down from the surface creating what is called the “active layer”. Active because there is free water there and the plants can grow seasonally. The active layer can be from 30 to 250 centimetres deep. But in winter, permafrost reigns supreme and ice lenses form in many places.
When ice forms, it expands and takes up more space than the water did. The force of that expansion shapes many features in the tundra.
Cracks in the soil accumulate water in summer. When it freezes in winter, the ice wedges push the soil and organic matter into shapes dictated by the ice-filled cracks. Several types of “patterned ground” result. The patterns depend on the nature of the underlying soil or the overburden of peat. As the ice wedges push on the sides of the cracks, the soil and organic overburden are elevated. That upward movement also raises the soil and organic matter out of the endless surface water and the improved drainage is reflected in improved growth of plants on these ridges. Those improvements result in small mammals shifting their foraging and movements to these little ridges. So everything can take on a pattern of polygons all arising from the pattern of soil cracks and the driving force of permafrost and ice in the ground. For more details, see E.C. Pielou’s excellent book, A Naturalist’s Guide to the Arctic 1.
The commonest form of patterned ground is ‘hummocky terrain’ — the bane of walkers. Ice plays some role in forming these hummocks (some have ice-cores) and as they elevate, plants respond with better growth on the top, thus amplifying the pattern. They are never spaced for easy walking and if you misstep and land in between, you often get a soaker.
Even when the frost has been melted down through an active layer, there still is permafrost for up to 250 metres below. That deep permafrost seals up the soil and prevents water draining down through it. So even with a near-desert, annual precipitation of only100 to 170 millimetres (4 to 7 inches), the tundra has more wetlands than drylands. The water that does come stays because physical evaporation and transpiration by plants are both very low. Rubber boots are de rigeur and the small mammals would love to have some. Moist meadows and semi-marshlands of cotton grasses, other sedges, and rushes fill low areas, valleys and drainageways with very highly productive plant communities. The sedges in these meadows are highly nutritious; they have up to 17% protein when the snow covers them at season’s end and still have 7% under the snow in mid-winter.
The production from these plants puts much dead plant material on the surface of the ground every year, despite the short growing season. That same shortness of the growing season, and the low temperatures and the widespread surface water, all combine to slow the natural process of decomposition. A little time on the tundra convinces an observer that organic matter is accumulating. Much of the ‘soil’ and several types of small landforms are composed entirely of organic matter. Decomposition is slower than production of plant matter. This build-up of organic matter from “green magic” makes highly organic (vs. mineral) soils widely common on parts of the tundra. These stores of organic matter are also stores of carbon taken from the atmosphere by “green magic” and not yet returned to the atmosphere. A ‘carbon sink’. If global climate warms the decomposition process in the tundra, a very large amount of carbon will be returned to the atmosphere instead of being stored for long periods on the tundra. That carbon will escape both in its oxidized form, carbon dioxide, and from anaerobic layers, as an even more effective greenhouse gas, its totally unoxidized form, methane.
Like most other landscape-scale (big, widespread) ecosystems, the tundra is a mosaic of patches of differing habitats — a heterogeneous mosaic. The tundra is not all organic soils, or all wet meadows. In fact much of the tundra has no soil of any sort and few plants. The plants do try hard and there will be one or a few in any crevice that has caught a bit of organic matter and held it or has accumulated a bit of mineral soil from rock breakdown. One of the most beautiful images in the tundra is a single plant blossoming out of a wall of rock.
Development of vegetation, as opposed to single plants, on bare rock depends on the rock gathering and holding a supply of water. Compared to the flat tundra, covered in organic soils, bare rock is a real desert. As plants get a start in a crevice, they add some organic matter and that holds moisture, and eventually, as a mat of mosses or other vegetation develops, a constant supply of moisture will allow development of a diverse plant community in an organic mat layered over the bedrock.
In the tundra, barren rock is actually a friendly place in some ways. In winter, muskoxen will gather against a rock wall where the rock is conducting heat up from deeper in the earth’s crust. The muskoxen have known about geothermal heating for a long time. Rocks can also offer protection to plants by warming and also by providing shelter from the wind.
One of the hazards on the tundra is wind. In summer, it can dry out soft plant tissue and kill it. In winter, ice crystals are blown at very high speeds just above the surface of the snow. Arctic sandblasting! Hiding behind a rock is a favourite trick of small soft-tissued plants to escape such effects of the strong winds of open plains.
Bare bedrock is common in environments as young as the tundra simply because soil takes a long time to form with such short seasons for rock breakdown and decomposition of organic matter to form compost. Although freezing speeds up breakdown by splitting rocks, further breakdown to actually release nutrients depends on chemical processes that are seriously slow.
The tundra is young because the glaciers melted off it as little as one or two thousand years ago. The commonest signs of recent glaciation are eskers, ridges of sand, gravel and rounded, water-washed boulders. Eskers began as the load of gravelly material that was being carried in the bed of a stream flowing in the glacial ice. When the ice melted completely, the gravelly bedload was dumped upside down on whatever the stream was passing over. So eskers are long winding ridges, shaped like an upside-down stream bed and crossing whatever is in their path. If an esker comes to a lake it simply continues underwater and up and out the other side. A band of big boulders marks where eskers crossed modern-day rivers. The river has washed away all the sand and gravel leaving a ‘rock garden’ to challenge canoeists.
Eskers are valuable habitat features for arctic wolves. The elevation and the coarse-textured soil make eskers favourite sites for dens for birthing and raising pups. Eskers also provide good vantage points for the wolves and are easy paths for travel. Tent rings show that the aboriginal people also camped on these high, dry ridges.
Because eskers are full of rock fragments sheared off and carried long distances by the glacier, they may have pieces of fine-grained quartz among their various kinds of rock. The indigenous people knew of these treasures and evidence of arrow- and spear-point ‘factories’ can still be seen along some eskers.
Clearly, the tundra is not “the barrens”, in terms of aesthetics, or monumental beings such as muskoxen or polar bears, or in terms of a source of spiritual renewal. Even in such gross terms as crop production values, the tundra is not barren in any absolute sense. One can calculate the forage that is gathered from the tundra by grazing animals and the herbivore body mass that would be produced from that forage. For muskoxen in the low arctic tundra, the calculation shows that 1.8 muskox per square kilometre can be produced. For caribou, the tundra can produce 4.8 animals per square kilometre. These numbers would not support a ranch but why should we look at the tundra as a ranch; the pressures of economics make that into another attempt to appropriate an ecosystem for selfish support of humans. Instead, the first nations attempted to become part of the ecosystem and let the ecosystem’s processes define their share of the production.
If we wish the tundra ecosystem to continue to grace our planet, we should understand its fundamental differences from other, commoner ecosystems. The tundra has many fewer species. Each one plays a larger, more critical role in the system’s processes. Losing one species, such as the polar bear or the muskox would have a much greater impact on the integrity of the tundra ecosystem than would losing several species from a species-rich tropical system. This is a weak point in much of the biodiversity discussion; without assessing the ecological importance of each species, simply counting species is more like stamp collecting than conservation biology. Recommendations have been made, by eminent taxonomists lacking arctic experience, to focus all our conservation resources on the 25 tropical and subtropical areas with the greatest species counts while allotting few resources to a species with the ecological (and cultural) importance of the polar bear; such directions are unwise. Racking up a large collection of species in our ‘saved’ collection should not be the single goal of conservation biology.
Compared globally, the tundra is a very special place. It supports ecosystems that are spartan. Trimmed by the rigours of the environment — severely limited solar input for “green magic”, cold and dry and needing subsidies from the ocean. These selective forces allow only the most fundamental of natural forces and only the most adaptable species to continue. The resulting ecosystems are the simplest, landscape-scale ecosystems to have stood the test of time and natural selection. Climate change and human activities are impacting the arctic heavily and consequently affecting the Tundra. These systems are essentially the polar opposite of the high-diversity, tropical systems — a different class of living system.
Yet despite the simplicity of tundra ecosystems, their grandeur and their beauty are exceptional. As natural riches, they are invaluable — and irreplaceable.
1 A Naturalist’s Guide to the Arctic, by E.C. Pielou, University of Chicago Press, Chicago. 1994.
Table of Contents
|1||GM||Coppermine River, NU|
|2||JA||Bathurst Inlet, NU|
|3||AM||Richardson Mountains, NT|
|4||GM||Coppermine River, NU|
|5||GM||Dog Island, NL|
|6||JA||Bathurst Inlet, NU|
|7||GM||Bathurst Inlet, NU|
|8||GM||Bathurst Inlet, NU|
|9||GM||Bathurst Inlet, NU|
|10||GM||Fish River, NT|
|11||GM||Youngs Harbour, NL|
|12||GM||Youngs Harbour, NL|
|14||JA||Athabasca Lake, NT|
|15||GM||Coppermine River, NU|
|16||GM||British Mountains, NU|
|20||GM||Coppermine River, NU|
|21||GM||Coppermine River, NU|
|22||GM||Coppermine River, NU|
|23||GM||Coppermine River, NU|
|25||GM||Thelon River, NU|
|26||JA||Bathurst Inlet, NU|
|27||JA||Bathurst Inlet, NU|
|28||GM||Moose River, ON|
|29||GM||Coppermine River, NU|
|30||AM||Thelon River, NU|
|31||JA||Bathurst Inlet, NU|
|32||GM||Thelon River, NU|
|33||GM||Thelon River, NU|
|34||GM||Thelon River, NU|
|35||GM||Coppermine River, NU|
|36||GM||Coppermine River, NU|
|45||GM||Youngs Harbour, NL|
|47||GM||Thelon River, NU|
|49||GM||Thelon River, NU|
|52||GM||Thelon River, NU|
|53||JA||Bathurst Inlet, NU|
|54||GM||Thelon River, NU|
|55||GM||Thelon River, NU|
|56||JA||Bathurst Inlet, NU|
|JA – copyright © Jeff Amos|
|AM – copyright © Aileen Merriam|
|GM – copyright © Gray Merriam|