Excursion to the Arctic Circle

Natural History, July, 2000 by Robert H. Mohlenbrock

The Yukon Territory's Dempster Highway takes motorists through mountains and tundra.

During the late nineteenth century, the great Klondike gold rush created a well-beaten path to Dawson City, but the northern reaches of Canada's Yukon Territory long remained relatively inaccessible. The construction of the Dempster Highway, which was completed in 1979, established a road link from near Dawson City (now simply called Dawson) all the way to Inuvik, in the Northwest Territories. This gravel (and sometimes dirt) road is one of just two public highways in North America that cross the Arctic Circle; a third is under construction. Intent on exploring the environment along this route, my wife and I set out on the highway very early one August morning, with plans to drive north and reach the outpost of Eagle Plains, 255 miles away, by nightfall. Because no services or facilities are available in between (except for a couple of government-operated campgrounds), we made sure our vehicle--appropriately, a GMC Yukon--had a full tank of gas.

Early morning is a great time to observe wildlife, and very soon we saw moose, bald eagles, red foxes, and ptarmigan. For some distance, the highway passed through boreal forest, where white spruce and balsam poplar are the dominant species. Before long, the Ogilvie Mountains came into view in the distance, and eventually we neared the craggy peaks of Tombstone Mountain. Approaching the visitors center for the Tombstone campground, located at kilometer 71.5, we saw a grizzly bear feeding halfway up the mountainside. Unfortunately, it was scared away when a highway-department truck came rumbling along the road.

As we continued our drive northward, the forests soon began to thin and patches of tundra appeared. At North Fork Pass (4,265 feet above sea level), we crossed the Continental Divide. The highway then passed through two river valleys before again crossing the divide, which zigzags through the territory. Our journey continued on a relatively flat, high plain. Along the way, we stopped several times to make short forays on foot to get a closer look at the tundra. Our boots were absolutely essential for traversing the flooded ground.

Dominated by low-growing vegetation, tundra is a habitat that extends from the polar ice cap south to the boreal forest. The ground is underlain by permafrost, a layer of soil that remains frozen throughout the year and that may extend deep into the earth (in Siberia, it has been reported at a depth of 4,757 feet). Generally, permafrost develops in glacier-free polar regions because glaciers are excellent insulators and keep the ground beneath them from freezing. The northern Yukon (not covered by ice during the last continental glaciation) is primarily tundra, while the southern Yukon (once covered by glaciers) is now mainly boreal forest.

Tundra soil is usually acidic and poorly aerated, and although high in organic matter, it offers limited nutrients for the growth of vegetation. Roots cannot penetrate the permafrost, so tundra plants have shallow root systems. And because water cannot penetrate it either, there is little drainage after rain or snowmelt. As a result, numerous shallow pools develop during the summer, transforming the tundra into an extensive wetland. When vegetation is removed from the tundra--for example, as a result of construction activity--the Sun's rays begin to thaw the permafrost, the soil erodes, and the ground slumps.

Because of the harsh environment, most plants that survive in the tundra are dwarfed, and many have stems that creep along the ground. Some wildflowers, known as cushion plants, form a tight, rounded cluster of closely arranged stems and leaves. The cushion shape reduces the plants' surface area and thus lessens their exposure to the elements. Most tundra plants are perennials, and the greater part of their tissue is underground, where nutrients are stored.

A showy grass known as foxtail barley was common along the highway, while here and there we saw bogs dominated by black spruce and larch. These bogs, called muskegs, are often dotted with pools of water and are extremely spongy underfoot because of the underlying layers of peat, which consists of decayed sphagnum moss. We also stopped at a dry ridge top where rocks had been heaved to the surface by cycles of freezing and thawing that sorted them into a honeycomb pattern.

It was nearing 8:00 P.M. when we arrived at Eagle Plains, an outpost settled just before the completion of the Dempster Highway. This oasis in the tundra consist of a hotel, a restaurant, a gift shop, and a service station. The hotel is built on an outcrop of bedrock--the only place in the area where the ground is not permafrost. After refueling our vehicle, checking into the hotel, and getting a quick meal, we headed north again for another twenty-two miles so that we could say we'd reached the Arctic Circle. Here, at 66 [degrees] 33' north latitude, the Sun remains visible for a continuous twenty-four hours on the summer solstice. Although we finally got to bed in the Eagle Plains Hotel at about midnight, it was 2:30 A.M. before the Sun went down, only to rise again a couple of hours later. By 7:00 A.M., we were on our way back to Dawson via the same exciting route.