Thursday, December 31, 2009

New Year's Eve at the Boardwalk

This afternoon my daughter Susan and I walked around the Boardwalk and for a change we had it all to ourselves. Maybe that's because the temperature was -20 and there was a stiff breeze. Regardless, tracks in the snow showed that others had braved the path before us. And there were other stories written in the snow. We saw numerous tracks of snowshoe hares, especially where the brush was thick.

Snowshoe hare populations follow a cycle that peaks about every 10 years before crashing. We must be near the peak this winter because there are lots of hare tracks.

The hares get their name from their enormous hind feet which serve as snowshoes to keep their owner from sinking into the soft snow. I think it's pretty likely that people copied the hares when the first human snowshoes were invented. In typical rabbit family fashion, hares hop with both hind feet, and the hind feet actually land ahead of the front feet in the somewhat heart-shaped track.

Snowshoe hares use the same trails over and over again to move between feeding and resting areas. Some of these cross the Boardwalk, either under or over depending on how far above the snow the structure is. I looked underneath at one crossing location and found where a hare had rested. Hares spend their resting time in sheltered locations called forms and it seems at least one hare thought the Boardwalk made an excellent shelter.

All the best to everyone for a prosperous New Year!

Wednesday, December 16, 2009

Trees of the Boardwalk - Lodgepole Pine 1

Although the lodgepole pine is the most abundant tree species in the Alberta Foothills, it isn't very common around the Beaver Boardwalk. Partly that's because the local soils are very calcareous and pine prefers more acidic soils. Another likely explanation is the history of fires in the area and how pine reproduces. Some people call the lodgepole pine the phoenix tree. Why? Because lodgepole pine requires fire to assit the reproduction process. Like the mythical phoenix a new pine generation rises from the ashes of parent trees scorched by forest fires.

Pine cones contain the secret. Cones take two growing seasons to mature after tiny yellow pollen grains produced by tan-coloured male flowers fertilize the reddish female flowers. Each summer pine and spruce trees produce huge quantities of pollen blown by the wind to female flowers. The excess pollen coats surfaces and forms a yellow film on puddles, and makes some alergy sufferers miserable.

Mature pine cones remain fixed to the parent tree. Cone scales protecting the precious seeds remain tightly locked by a bond of resin, waiting for a fire. It takes a temperature of 45-60°C to melt the resin and release the seeds. Normally that much heat is only produced by a forest fire, which kills the trees but doesn't completely burn the cones. The seeds fall to a cooling and fertile ash bed on the forest floor, where they germinate in incredible numbers.

Pine seeds aren't easily dispersed by the wind or other agents. In nature, fires must usually kill cone-bearing trees to establish a new generation. If there are no pine trees to kill or fires occur infrequently, other tree species replace pine as dominant species in an area.

Sunday, December 6, 2009

Bear Tracks

It's a pretty fair bet that most local bears have entered their winter dens, but it's still possible to see bear tracks in the forest if one looks carefully. Several aspen trees along the Beaver Boardwalk have old scars in their bark made by black bear claws. Let me qualify that - the marks were probably made by black bears. Young grizzly bears can climb trees, but they don't do it a lot. I wouldn't either if I were a grizzly cub with such a powerful Mom to defend me.

Black bears climb trees for lots of reasons. Getting food and escaping danger are probably the most common activities. The method is pretty straightforward. A bear grabs the side of the tree with it's front paws and their longer claws, jams the shorter claws on the hind feet into the bark, and hitches up the tree front to back. Black bears can go both up and down pretty fast - as fast as or faster than human climbers you see in lumberjack competittions.

Bruin claws easily penetrate the relatively soft and smooth aspen bark. Damaged bark darkens as the tree heals from the injury, leaving a permanent record of the claw marks. So why climb aspens? The smooth bark is fairly slippery when compared to other local tree species, as anyone who trys to shin an aspen could tell you. Of course, people don't have nice sharp claws to assist the process.

Every spring hungry black bears climb a lot of aspen trees. They are after the nutritious reproductive catkins that appear very early in spring greenup when there's not much else for a bear to eat. I once flew over a patch of aspens on an early spring evening and saw 5 black bears up in the treetops feasting on catkins. That aspen patch was the only one in the area. It drew bears like a magnet, but only for a very short period of time that I was fortunate to witness.

Thursday, December 3, 2009

Trees of the Boardwalk - Tamarack

Alert folks have noticed that the interpretive sign describing tree species found in the Beaver Boardwalk area was missing a prominent local species. That's because there was no tamarack close to the trail in the first two years. However the 2009 construction passes by lots of tamarack. The resolution of the original sign was also below standard, so we're redoing the sign and the new version will include Larix laricina.

The tamarack is an oddball tree in one respect. It's a conifer, which means it bears its reproductive structures in cones. But unlike most local conifer species that have evergreen needles, the tamarack needle clusters turn a deep gold in the autumn and join the parade of falling leaves from aspens and poplars.

In our area tamarack usually grows in fens, which are wetlands on organic soils that have water flowing through them. This makes them more nutrient rich than bogs, which usually have stagnant water. The relationship is so strong that tamarack trees are diagnostic - if you see a tamarack you are likely looking at a fen.

The word tamarack comes from an Algonquin word that translates loosely as "wood used for snowshoes". The tough springy wood of this small to medium sized tree is also used for posts and poles because its high resin content provides good decay resistance. The James Bay Cree use tamarack twigs to make goose decoys which are true works of Canadian artisan craft.