Ivvavik National Park of Canada
The Arctic is a place of extremes, whether referring to the daylight, the temperatures or the weather. With a month of darkness in the winter and two months of twenty-four hour daylight in the summer, plant and animal life must take advantage of the short growing season, and have the ability to endure the harsh, long winters.
The average summer temperature in Ivvavik is 14°C, and the average temperature in winter is -29°C. The annual precipitation is small enough that the Arctic is actually classified as "desert."
Coastal areas are largely influenced by maritime air masses. More continental subarctic conditions (e.g. less fog, less precipitation, larger fluctuations in temperatures) prevail in the centre and southern areas of the park. The British Mountains constitute a significant topographical feature that influences the regional climate.
The British Mountains
British Mountains near Imniarvik.
© Parks Canada / Karsten Heuer
The British Mountains dominate Ivvavik, accounting for about two-thirds of the park's area. These mountains, along with the Barn Range to the east, the Alaska Brooks Range to the west and the Old Crow Flats to the south, were not glaciated but formed a vast ice-free land mass called Beringia.
The ice-free area extended into eastern Siberia, crossing the Bering Sea via a wide land bridge. Beringia was a refuge where plants, wildlife and people lived during the last glacial period of 30,000 to 14,000 years ago. As the continental ice sheets melted, colonization of the surrounding lands took place. Many features in the park are typical of non-glaciated landscapes. V-shaped valleys, isolated conical hills and sideslope rock outcrops called 'tors' are the most obvious ones. The principal forces shaping the land are frost shattering, wind and water erosion, and the forces of gravity which slowly move material downslope. The ridges and peaks of the British Mountains range from 860 to 1,680 metres above sea level. These mountains increase in ruggedness from east to west. The Babbage, Firth and Malcolm river valleys carve their way through these mountains in a southwest to northeast direction. For thousands of years these valleys have been travel routes for wildlife and humans alike.
The Firth River
Lower Firth River Canyon.
© Parks Canada / Karsten Heuer
The Firth River provides a natural corridor for a rich variety of wildlife, and for park visitors who want to see the diverse arctic landscape. The river offers 130 km of navigable river from Margaret Lake (near the Alaska border), northward to the Beaufort Sea. The flow of the Firth is relatively slow through the initial wide river valley, but increases in force as the valley narrows as it approaches Joe Creek.
Travelling past Joe Creek, the river gradient increases and numerous boulder gardens ranging from Class II and III+ are encountered. About halfway to the ocean the Firth River enters a canyon and does not emerge until it reaches the coastal plain. As the coastal plain is approached, the river slows and braids, forming a delta as it empties into the sea at Nunaluk Lagoon.
Associated with the many springs is 'aufeis'. During the winter, percolating water freezes forming ever-thickening layers of ice. There are extensive sheets of this aufeis upstream of Margaret Lake, as well as on some of the Firth's tributaries, delta, and on other park rivers. This ice can often persist throughout the year.
The Coastal Plain
© Parks Canada / Ian McDonald
The coastal plain is a band of flat to rolling topography extending from the Bucklknd Hills north to the Arctic Ocean. The width of the coastal plain varies from 30 km in the east to 10 km in the west. During the last ice age a tongue of the continental icesheet extended westward from the Richardson Mountains; it advanced along the plain to a point about halfway between the Firth and Malcolm rivers. As the glacier receded it left in its wake piles of sedimentary deposits. Some of these hills of glacial debris scattered along the Buckland Hills harboured chunks of glacial ice which have since melted and collapsed into kettle-like depressions. These depressions, often filled with water, are distinctive features of the landscape, as are the meltwater channels that once contained glacial floodwaters.
Today, the coastal plain is influenced by the cooling effects of the Beaufort Sea. Snow and ice arrive by early October and do not melt until late May, and even then the sea is still frozen. Throughout the summer, ice floes and pack ice sit offshore and can blow in anytime. The ever present ice cools the air, delaying the onset and reducing the length of summer. The ice also creates fog banks which can make days cool and wet. As on all arctic coasts, wind is a factor and is cool even in mid-summer when it blows in from the north.
The Beaufort Sea
Beaufort Sea at Nunaluk Spit.
© Parks Canada / Karsten Heuer
The entire northern Yukon is rimmed by the Beaufort Sea, a section of the Arctic Ocean. This is an ocean that is gripped in ice for at least eight months of the year. Open leads start developing along the coast in April, but the landfast ice does not break up and drift away until June or even July. The frozen nature of the Arctic Ocean makes it technically difficult and expensive to study and it is the least understood of all ocean basins.
The direction of offshore currents affects the shoreline topography as well as the habitats and movement patterns of wildlife. Shingle spits and islands, oriented parallel to the shore, offer important nesting habitat to the sea birds. Brackish lagoons, protected from the open ocean by spits, are important feeding areas for both birds and fish. Ocean currents affect the location of open water leads in the landfast ice each spring. Seals and whales depend on these leads to navigate to areas important for feeding, whelping and calving.
The same currents carry driftwood westward, from the mouth of the Mackenzie River, dispersing logs along thousands of kilometres of coastline. The logs provide essential habitat for a variety of small mammals and nesting birds. In the past, humans depended on driftwood for warmth and shelter while on the coast. The many driftwood shelters, sod roofed huts and grave sites are evidence of this.
Travelling the Firth River is an ideal introduction to the region's geological history. The most dramatic story is evident in the layers of sedimentary rocks that are exposed in its canyon walls. The oldest of these rocks were once sediments that were slowly deposited in an ocean basin between 580 and 380 million years ago. At that time, the shoreline of the North American continent lay several hundred kilometres to the south and east. Since then the northern Yukon has emerged, risen and fallen repeatedly in a succession of mountain building and erosion episodes.
About 400 million years ago, massive plates of the Earth's crust changed their patterns of motion. Around the world, mountain ranges soared skywards when crustal plates collided. In Ivvavik, evidence of uplifting is exposed in the canyon walls of the Firth River as intensely folded layers of shale and limestone. The landscape has since been worn down by countless years of wind and rain.
Sediments, deposited either on the ocean bottom or by rivers that traversed broad floodplains, formed horizontal layers of rock on top of the deformed beds. Over time, sediments became the limestone, sandstone and shale that form the foundation of the park. Some sediments were deposited during periods of much warmer climate than today.
This story is told, in part, through the fossilized remains of plants and animals preserved in the region's rocks. Skeletons of marine animals, known only to inhabit warm waters, are preserved in canyon shales. Corals, fossilized in limestone, can be found throughout the southern portions of the park.
Even though we are between glacial ages at the moment, the climate of the northern Yukon is still a harsh one. Winters are long and cold and summers are all too short. The average temperature over the year is so cold that the majority of ground in the park is permanently frozen.
Despite this, the northern Yukon in summer can be surprisingly lush and teeming with life. Any precipitation that does fall, along with the melting snow, sits on the surface. Water is then available for a range of plants and animals that would not otherwise survive. As well, the warm summer sun is able to melt the upper layer of ground to varying depths, thereby freeing up soil for root development.
The continual freeze-thaw action on the different types of soil and substrates produces a variety of features that are distinctive to permafrost terrain - hummocks, tussocks, frost boils, sorted and non-sorted circles, and high and low centred polygons. Solifluction lobes, a layer of thawed soil sliding on top of a permafrost layer, creep downhill. Subsurface rocks squeeze to the surface, piling up in vertical slabs. Wedges of underground ice, exposed along river banks and shorelines, melt in the summer sun and cause mud slides and ground slumping. The landscape of the northern Yukon has been created as much by the effects of its frozen ground as it has been by the more dramatic forces of its geology.
Wild crocus ( Anemone patens L. ).
© Parks Canada
There are three main vegetation types in the park: arctic tundra, alpine tundra and taiga. Arctic and alpine tundra are the most common. Taiga is the transition between boreal forest and tundra. It consists of open stands of stunted spruce and balsam poplar. These trees grow to within 30 kilometres of the Beaufort Sea and represent the northernmost extension of their range in Canada.
Depth of permafrost and availability of moisture both affect the distribution of plants in the northern Yukon. Day length, air and soil temperature, exposure to wind, and snow conditions also have an impact on how and where plants grow. In the Firth River valley, the more delicate flowering plants as well as stands of stunted trees grow on south-facing mountain slopes and stream banks. These areas are protected and receive plenty of direct sunlight. As a result, permafrost is lower in the soil. The Malcolm and Babbage river valleys are strongly influenced by Beaufort Sea weather: frequent fog, cool temperatures and steady winds. Typical vegetation of these valleys include tundra grasses, sedges, herbs and low shrubs.
On the coastal plain, with its proximity to the ocean, permafrost is close to the surface and precludes the growth of trees and many other plant species. The tallest plants here are willows that grow along the ground. Polygon wetlands are filled with arctic grasses, rushes and sedges. High-centred polygons, hillsides and ridges are covered with blueberries, cranberries and cloudberries. Wildflowers bloom throughout the park with the peak of colour occurring from late June through early July. Blooming is delayed in places where snow lingers (e.g. on the coastal plain) or has accumulated (e.g. along river banks or on the leeside of hills).
All plants that grow in the Arctic have evolved the means to live in harsh conditions. Some species develop a thick layer of protective fuzz to protect them from the cold. Others find protection by growing in cushions or mats. Some plants angle their cup-shaped flowers to the sun, thereby concentrating the rays onto the seed heads in the flower's centre. Others have dark coloured hairs which absorb more solar heat. Most arctic plants are low growing, finding more suitable conditions closer to the ground. Many of these plants change colour in mid to late August, leaving a brilliant patchwork of yellow, orange and red across the landscape.
© Parks Canada / Wayne Lynch
The northern Yukon, with its diverse vegetation, is able to support a wide range of animal life. Many mammal species move freely between vegetation zones while other animals prefer very specific habitats.
The Porcupine caribou herd migrates annually from the forested valleys of north-central Yukon to calving grounds on the Beaufort coast. Muskoxen prefer the open tundra of the coastal plain, but will sometimes wander south into the mountain valleys. Polar bears spend most of their time north of the park hunting for seals amongst the open leads of the offshore pack ice; however, they do come ashore throughout the year, especially during winter. Grizzly bears range over the entire park. Red and arctic fox are both found in Ivvavik. Dall's sheep are at the northern limit of their range here in the British Mountains. Moose occasionally wander onto the coastal plain but prefer to forage in valley bottoms. Wolves and wolverine travel wherever there is enough prey to sustain them. Marten and porcupine are forest dwellers that venture as far north as the treeline.
The arctic ground squirrel thrives wherever it can find soft soil for burrowing. The same holds true for other species that den underground. There are six species of voles in the park and two of lemmings. The singing vole is noteworthy, being the most vocal. Its high-pitched trill can be heard echoing across the tundra. Lemmings, renowned mainly for the cyclical nature of their populations, litter the tundra with their trails, burrows and caches of winter hay.
Ivvavik, together with the Arctic National Wildlife Refuge to the west and Vuntut National Park to the south, protects approximately 94,500 square kilometres of land. This area, as large as it seems, is only a small part of the circumpolar region. Species like the barren ground caribou need vast tracts of undeveloped land. Their movements do not stop at park boundary lines or along international borders. Ivvavik does, however, provide a refuge that with careful management, will be able to sustain healthy populations of wildlife for many years to come.
Arctic grayling and Dolly Varden char are the best known fish species in the park. The most distinctive feature of grayling is their large dorsal fin that ripples like an unfurled sail. Grayling feed extensively on insects, of which there are an abundance in the northern Yukon. The Firth and Babbage rivers host healthy populations of char. Most char are anadromous: migrating each summer to the Beaufort Sea to feed and then back to the fresh river waters to spawn and overwinter. Underground springs occur on several of the rivers and creeks in the park. At some of these springs fresh water continues to percolate to the surface year-round. As a result of this continual flow these waterbodies do not freeze to the bottom. It is here, in the fish holes, that char and grayling can overwinter.
© Parks Canada / Brian Johnston
Ivvavik National Park is important habitat for a wealth of migratory and resident bird species. In a world where bird numbers are declining due to habitat destruction, Ivvavik offers a safe refuge for birds to breed and raise their young. Some migrants (northern phalarope, golden plover) travel from as far south as Patagonia in Chile, and some even from Antarctica (arctic tern). Others, like the Northern wheatear, yellow wagtail and bluethroat migrate from across the Bering Sea. Some species, such as the snowy owl, ptarmigan and hoary redpoll, are year-round residents and have developed strategies to survive the cold and lack of daylight. Ravens and gyrfalcon are so well acclimatized that they can start nesting as early as April.
Most birds that breed and nest in the northern Yukon cannot survive the rigors of winter. As the sun returns to the Arctic, so too do the majority of birds. Many arrive when there is still snow on the ground, and do not leave until after the first frost. It is a short season to ensure the survival of their species, and the tundra fills with life during the long days of summer.
The numerous lakes that dot the coastal plain, the rich deltas and brackish lagoons, and the shallow marine passageway all offer essential avian habitat. So too do the mountain valleys, canyons, tundra uplands and forested slopes. By August, the sounds of breeding and nesting are over and autumn migrations are underway. Snow geese, southbound from arctic island nesting grounds, descend on the coastal plain by the thousands in early September. By the time they leave, the ponds are freezing over and winter is only weeks away.