Stop # 1. At the Divide

Looking Four Ways

To the north our view is of sharp and angular mountains, typical of mountains that have not been over-run by glaciers Figure 1.1b. In the valley beyond the hills is the Firth River, which flows northeast to the arctic coast. We are standing on the arctic divide where all waters to the north flow to the Arctic Ocean, and all to the south flow south and west to the Bering Sea via the Yukon River system. Vuntut National Park shares the western half of its northern boundary with Ivvavik National Park, and everything we see looking north is in Ivvavik.
Figure 1b. At the divide between watersheds. Click photo to enlarge.

Looking to the west we see over the international boundary into Alaska. On the other side of the border is the extensive protected area called the Alaska National Wildlife Refuge. Just on the other side of the Firth River, as it crosses the boundary, is Riggs Mountain, from which the local ecodistrict takes its name. (Riggs was the leader of the American part of the team that surveyed and marked the boundary in 1911-1912).

Looking out to the south we can see the huge bowl-shaped structure known as the Old Crow Basin (Plate III). Lying between the eastern and interior mountains of the northern Cordillera, the Old Crow Basin consists of the Old Crow Flats which form the floor of the basin, the British, Richardson, and Old Crow Mountains which form the Basin's upper rim, and the slopes between the mountains and the Flats which form the sides of the Basin.

To the east beyond the ridges is a lowland which is the origin of both Muskeg Creek, which flows north into the Firth River, and Timber Creek, which is our route south through the Park. Beyond the lowland is "Horseshoe Hill", a structure shaped like a volcano, that marks the boundary between Ivvavik and Vuntut National Parks.

Everything that can be seen from this point, in all directions, is part of a huge area of land in Alaska, Yukon, and northeastern Russia that remained generally ice-free during the time of the last Ice Age. Known as Beringia, this area is now separated into eastern and western parts by the Chukchi Sea, Bering Strait, and the Bering Sea. Many plants and animals that exist in the area today are thought to have survived in Beringia during the last ice age. Some "Beringian species" survived the ice ages in the northern Yukon refugium area, then dispersed outwards. Others that survived in this glacial refugium are not found elsewhere in Canada. This role as a glacial refugium has had a major impact on the distribution of many life forms, including invertebrates and plants, as well as the more obvious birds and mammals. It also has a lasting legacy in the form of one of the world's most abundant deposits of Ice Age fossils.

Since the northern Yukon was not covered by continental ice sheets during the last glaciation, the underlying geologic structure in this region has not been extensively modified by glaciers as has so much of Canada. However, there are many other geomorphic (earth-shaping) processes which have affected the landscapes of the Old Crow Basin. In the northern parts of the area especially, where vegetation is sparse and does not cover much of the ground, these ongoing processes are easily seen.

The particular features of this view point area at the northwestern tip of Vuntut National Park result in it being classified as part of the British-Richardson Mountains Ecoregion. This Ecoregion is very mountainous and streams are probably typical snow-fed arctic mountain streams and may even dry up in at the height of summer. More details about the ecological land classification of the Park and Special Management Area are found in Appendix I and Plates V, VI, and VII.

Looking At Your Feet

Here in the mountains it is easy to appreciate the underlying geological structure of the Park. It is perhaps less easy to see how the structural geology influences the ecological relationships of the surface elements. The earth's surface, or substrate, upon which plants grow and animals move is a product of a varied geologic history and many physical processes working on the earth's surface. Over time, the underlying structure continues to be modified by ongoing processes which erode and deposit materials. The chemical composition of the bedrock itself influences the type of plants that can exist and also their rate of growth. Some rock types are never vegetated.

On our ridge top view point, there is little or no soil, but farther down the mountain slopes and in other areas with suitable conditions, soil is present. The bare substrate, necessary as a starting point for plant succession, is created through the wedging and shattering of rock by freezing, chemical weathering, frost heaving, movement of loose soil material or rock fragments deposited by rock falls or soil creep (colluvial movement), and deposition by streams associated with snowbeds. Under the harsh conditions of the arctic, soil development has unique features. A major characteristic of cold arctic soils is cryoturbation, the intermixing of surface sediments due to freezing and thawing, often resulting in a lack of the usual layers of soil known as horizons. Arctic soils are also characterized by their high content of ice.

When drainage of soil is poor, the layer of permafrost that melts in summer, called the active layer, often remains saturated with water. In this condition, soil can flow downhill, even on very shallow slopes, though the flow is usually conspicuous only on slopes exceeding 3 degrees. This soil movement (called solifluction) displaces unsorted surface materials and often results in long stripes of soil and stones and striking lobes of soil material. Occasionally, whole mats of vegetation can be displaced downslope without much disruption. Surface soil also moves by frost creep, where particles lifted by freezing are redeposited slightly downslope as they thaw. The same process can move even large boulders downhill. Although these processes result in an instability that disturbs vegetation and leads to barren habitats, at the same time, they can lead to an increase in the diversity of habitats downslope, especially habitats that occur on a micro scale.

On the higher mountains, alpine tundra vegetation consists of mostly crustose lichens and flowering plants and low shrubs, especially mountain avens and alpine bearberry. Arctic and alpine plants show a variety of adaptations: the cushion-like growth form of the certain saxifrages which helps to trap heat, the storage of nutrients below ground to allow for a quick start to growth in spring as shown by sedges, and the surface hairiness of the lousewort which cuts down on the loss of moisture to the wind (Savile 1972).

Up here on the ridge top, where conditions for growth are poor, we can see more easily the effect of geology on vegetation. Depending on the chemical composition of the rocks, different plant species may occur. While some plants seem to do well on any rock base, others "prefer" certain geological types. For example, the greatest number of species in alpine sites is found on limestone rocks like the ones here at the divide in northern Vuntut National Park (Welsh and Rigby 1971).

Mountain slopes are also a good place to observe plant succession, the gradual replacement of one type of vegetation community by another over time. In alpine tundra, succession proceeds from lichen communities toward dwarf shrub or grass tussock communities depending on the amount of moisture available. Frost action disrupts the successional sequence. On the alpine tundra of the Richardson and British Mountains it apparently takes a longer time to reach the point of a stable plant community than in forested areas where the presence of trees softens the effects of the environment (Hettinger et al. 1973).

On the slopes or at the foot of the mountains, the loose rock or scree slopes are mainly colonized by vascular plants. Where the site is more stable, sedges increase in abundance and in the Richardson Mountains sedges are followed by Lapland cassiope. In the British Mountains unstable slopes are colonized by dwarf willow and lichens. Fireweed and false asphodel become more abundant as the slope become more stabilized.

The combination of adequate warmth and moisture, along with specific landscape and soil conditions, can produce an area of increased growth and greater diversity of vegetation. For example, the vegetation of the northern part of the Park area is generally classified as low arctic (Edlund and Alt 1989), but certain conditions in sheltered river valleys permit the growth of trees in the northern parts of the Park beyond the designated treeline or northern limit of trees.

Looking Around

The numbers of birds that one would expect to see on mountain tops or hill crests is relatively low. Here where there is more exposed rock than plant cover, the food supply is limited and only a few species can exist. Most common are the typical arctic or alpine species, horned lark and American pipit, and less frequently, rock ptarmigan, Smith’s longspur and lesser golden plover.

This area is just south of where parts of the huge Porcupine Caribou Herd usually spend their summer season. They come to the cool and windy mountains to escape the hordes of biting insects that are found at lower elevations. Mosquitoes and parasitic flies are more active during warm summer weather forcing caribou to spend more time standing in insect relief areas such as late snowbeds and upland areas, and less time feeding (Russell et al. 1993). During July and August of some years, some caribou may use the uplands here in the northern part of the Park as insect relief areas (see Mammals).

Caribou may be found within northern Vuntut National Park at various other seasons depending on the routes and timing of migration. Caribou seldom pass through the northern and northeastern parts of the Park during the spring migration and pre-calving period. Some pregnant cows may stay in the northern part of the Park in the early June calving period if they are unable to reach the coastal calving areas on time (Porcupine Caribou Technical Committee 1993). During the fall migration the herd uses the northern part of the Park in less than half of the years for which information is available. Caribou migrating south from here are on the "Old Crow" migration route which brings them close to Old Crow in most years.

Looking Up

Seeking relief from insects in the mountains is one of many examples of how the living beings (such as caribou) in an ecosystem interact with the non-living components (such as temperature).

High in these northern Yukon mountains, all forms of life, from insects to humans, have had to adapt to a certain set of non-living factors that makes survival difficult at best. Most of these factors all ultimately derive from the relationship between earth and sun that leads to the extremes of arctic winter and summer. The conditions that we call "arctic" are a direct result of the earth's orientation to the sun and the earth's movement around the sun. These specific features of our solar system create the nature of the light that strikes the earth and the consequent temperatures on various parts of the planet. The tilt of the earth means that for part of the year the northern regions of the earth are facing away from the sun, losing the heat and light necessary for abundant life. The long cold winter with little or no radiation is followed by a relatively short summer growing season characterized by higher daily radiation than occurs in the tropics. This pattern of extreme seasonal changes in the incoming radiation from the sun leads to generally low temperatures year-round, limiting which plants and animals can survive and affecting their success.

As well as being one of the most important factors in the general ecology, climate also has an important impact on the landscape. Aside from the obvious link between climate and permafrost, there are strong links between precipitation, runoff and erosion; and between temperature, moisture availability and breakdown of bedrock. Climate, through runoff and erosion, also directly affects soil conditions and habitat, and therefore vegetation, wildlife, and the people who live on the land.

Looking Back

Although it would be unusual to see other people at the divide today, in past times people were more a part of this landscape. At certain times of the year, from this vantage point one might see people walking or driving a dog team over the divide from Thomas Creek into the valley of the Firth River. One of the Vuntut Gwitchin's Heritage Routes runs just west of here, connecting the Old Crow Flats to the Firth River and Herschel Island at the arctic coast (see History). The Vuntut Gwitchin also travelled in winter to the Fishing Hole on the Firth River to catch overwintering arctic char. In the late 1800s the people who lived part of the year at Rampart House (on the Porcupine River, 140 km south) also travelled this heritage route to trade at Herschel Island. This route was also used in travelling from Old Crow or the Old Crow Flats north to the caribou fences at Thomas Creek. In winters past the sound of bells would announce the arrival of a traditional Vuntut Gwitchin dog team.

As well as the traditional Vuntut Gwitchin movements through this area, there were also groups of Inuvialuit moving south to the Flats for fishing and trapping and to Rampart House for visiting and trading. Other groups moved into the area from Alaska to hunt caribou.

In the early 1900s prospectors working with Dan Cadzow, trader at Rampart House, explored for gold somewhere along the divide in this area. The impact of this early mining exploration on the ecosystem remains unknown as the location and extent of these activities are also not known.

During the early part of the last century, a significant impact on the ecosystem in this area from land use by Euro-Canadians would have been the activities of the International Boundary Commission survey parties in 1911 and 1912. The Commission surveyed the boundary between the U.S.A. and Canada to the Arctic Ocean, establishing camps and trails for the men and packhorses, cutting a broad path along the boundary through forested areas, and constructing boundary monuments. The trails used by the horses probably followed the heritage route where it was close to the boundary, especially near Rampart House.

To the southwest of this point the cut line of the boundary through the forested area can be seen where the boundary climbs from the forested valley to open hilltop(see Plate VIII).

The impact of scientific and other explorers on the wildlife of Vuntut National Park was probably not as significant as elsewhere, though hunters from the early expeditions used whatever resources were at hand, especially caribou. A more lasting impact was in how their presence affected future land and wildlife use by the Vuntut Gwitchin.