Cone Explosion

When the wind blows through my Jasper cul-de-sac, the spruce trees brace themselves against the gusts, the way millions of years of evolution have designed them to.

This year, however, the tops of some of the spruce are so laden with cones, it seems possible that with one good blast, they might just snap off.

This phenomenon can be seen everywhere around the park, from the middle of the townsite, to the sub-alpine near the Columbia Icefield. From a distance it looks like the tops of trees have faded to red, but it’s really an explosion of cones so prolific, the green conifer needles below can’t be seen.

Sally Aitken, professor of Forest and Conservation Science at the University of British Columbia, says there may be a number of reasons, or a combination thereof, that have caused this profusion of cones.

“In general, conifers will produce more cones the year after a hot, dry summer,” she explains. The buds that initiate the cones form during the hot spell, and the actual cones become visible the following year.

Aitkens says another factor in the production of a big cone crop may be that it is simply the right time in their reproductive cycle. Many trees only produce cones periodically—not every year. It’s a process known as masting.

“It takes a lot of energy to produce seeds,” says Aitken, explaining that they are high in fat and nutrients. “It’s hard for a tree to put resources into forming new buds at the same time it is expanding and developing this year’s cones.”

Masting helps trees get around a huge energetic output year after year.

Aitken says that masting may also help avoid the build-up of insects and animals (like squirrels) that feed on seeds. “It’s thought that through masting, trees space out their seed production, and then produce a seed crop that is just too big for the available seed predators to wipe out.” This ensures seed is left over to grow into new trees.

The cones that developed last year are even more obvious this year because they’ve grown bigger and browner, says Aitken, who suggests it’s likely this cone crop was initiated in 2012.

She says that regardless of the cause, bumper cone crops are a natural phenomenon. While some wonder if the abundance of cones is a type of “stress crop”—dying trees producing tons of cones in an attempt to pass along their genes en masse—Aitken says, “I don’t think that’s the pattern you’re seeing here, because the trees aren’t otherwise looking unhealthy.”

In fact, from what Aitkens says about tree ecology, it’s just the opposite. For whatever the reason, we’re looking at a massive cone crop on healthy trees.

There has got to be some squirrels pretty excited about that.