This past summer, I had the chance to visit this unique BC park, located just off Highway #5 (13 km north of Valemount and 6 km south of Tête Jaune Cache) with views of Mica Mountain, Mount John Oliver, Mount Arthur Melghen and Mount Lester Pearson of the Cariboo Range.

Jackson Flats is a beautiful and unique ecosystem of shifting sand structures and rare vegetation communities within the Upper Fraser Trench Ecosection of the northern Rocky Mountain Trench. This particular ecosection is xeric (dry) in the sub-boreal spruce (SCS dh) biogeoclimatic sub zone and supports four rare plant communities and two communities not found elsewhere. Though not immediately apparent, a highly diverse plant and animal community thrives here: lichens, mosses, fungi, beetles, ants, digger wasps, tumblebugs, many wildflowers among the junipers, stunted lodgepole pines, and occasional spruce, alder and poplar in moist depressions. Three species of lichen, one of which is not found in any other areas of the province, are considered endangered. This ecosystem is also home to moose, deer, coyotes, and martens, along with close to 40 species of birds.

The signs on the interpretive trail of the park tell us that to get a pure sand deposit like this one, you need two things: a source for the sand and a way to separate the sand from the mud and stones it is usually mixed with.

Origin of the Sand and Dunes of Jackman Flats in the Rocky Mountain Trench

The Trench itself is a large crack (fault) in the Earth’s crust. Geologists theorize that shifting plates compressed the crust, causing it to lift and form mountains. Further shifting caused the ridges of fractured crust to pull apart and the land in between dropped, creating the floor of the trench. Erosion and deposition of rivers and glaciers also contributed. During the ice ages a large part of the Rocky Mountain Trench was occupied by vast glacial lakes. For instance, glacial Lake Invermere spanned 210 km in the upper Columbia and Kootenay River valleys of the Rocky Mountain Trench, between Skookumchuck and Donald, B.C. The lake was 2.5 km wide and about 100 m deep. The northern end of the ice age lake was blocked by retreating glacial ice from the Trench and Beaver glaciers and the southern end of the lake was dammed by outwash gravel, till, and bedrock outcroppings.   

Glacial Lake & Jackman Flats

Rivers from the Cariboo Mountain Range carried mud, sand and gravel into the glacial lake of the Trench. When the climate warmed and the lake dried up, wind picked up what was exposed in the lake bed. It left the stones, blew the very light material down the valley in clouds of dust, and dropped sand-dune deposits in the flats. That’s how Jackman Flats was formed.

Unfortunately, this fragile ecosystem has changed with disturbance by people who do not keep to the designated paths. Trampling by motorcycles, bikes and walkers have destroyed fragile plants and exposed bare areas of sand, making them vulnerable to wind action and blowouts. Open shifting sand does not support much vegetation and can invade established areas. But a fragile layer of tiny mosses, lichens, and fungi—called a cryptogamic crust—first forms and begins to bind the sand together on the surface.

These blackish crusts that look like animal droppings help stabilize the sand, allowing larger organisms such as reindeer lichen, wildflowers and shrubs to establish and eventually restabilize the substrate. I saw areas of dune colonization by the cryptogamic crust, which seemed to consolidate the sands so other organisms could settle there.

The Pine Tree Trail

We started our walk on the Pine Tree Trail, heading toward the Juniper Trail. The area supported healthy lodgepole pines (Pinus contorta) growing amid low junipers, kinnikinnick, lichen and grasses. The lodgepole pine is one of the most widely distributed tree species in western North America and reproduces from seeds housed in their cones. The cones can be either closed (seritonous) or open (non-seritonous) and can shift from one to the other depending on the environment. In areas prone to fires the lodgepole pine produces serotinous cones (protected by a waxy coating) that require the heat of fire to release their seeds. Trees may produce up to 9,000 cones in a single growing season. I’m told that it is common for multiple years’ worth of cones to build up on a tree. The average serotinous cone can remain on a tree for at least 15 years, some lasting for decades, before a fire blazes through to open them. The lodgepole pine gets its name from its use in teepees and lodges; it remains highly desirable timber for rail fences, barn structures and log cabins. The lodgepole pine commonly lives to 150 years; some live up to 400 years.

Despite the beneficial role of wildfire in the regenerating natural succession of this ecosystem and the life cycle of lodgepole pine, this natural disturbance event has been eliminated by park managers for safety reasons; as a result, the pines are now more prone to insect and disease events. I saw a number of dead pines covered in charred cones that had burned some time ago. Poisonous fruticose wolf lichen (Letharia vulpina) covered man branches and cones with clouds of bright yellow-green. This lichen is somewhat toxic to mammals due to its yellow pigment vulpinic acid, and has been used historically as a poison for wolves and foxes. Wispy hair lichens, dark brown Bryoria known as Horse-hair lichen, hung off the dead branches. Grey-green Usnea, also called Old man’s beard, formed long tassels anchored on the bark and twigs of the old pines.

The Juniper Trail

As I made my way through the Juniper Trail, I saw large patches of what I thought was part of a sand dune. When I got closer, I realized that they weren’t sand patches at all; they were puffy colonies of pale-green reindeer lichen (Cladina mitis) growing amid grey clouds of coral lichen (Stereocaulon condensatum). They covered the ground everywhere, and in slight depressions accompanied by bearberry (Arctostaphylos uva-ursi) also called Kinnikinnick.

Unfortunately, off-path use by people, bikes and motorcycles has disturbed this fragile sand habitat, creating ever-expanding dunes. The colonization of sand by fungi and bacteria then lichen and moss and finally larger shrubs and grasses takes time. Given their value as burning wood, pine trees have also been illegally harvested from the park for firewood. Removal of the trees encourages wind blowouts and expansion of the sand dunes.