30 Aug 2011

Harvest Time in the Forest

posted by Claire Eamer

It's harvest time here in the Yukon, at the northern edge of the boreal forest. The leaves on the aspen trees are beginning to turn sunshine-yellow, the fireweed is crimson, and the high alpine bushes are showing red. People are out in the bush every weekend, picking berries and gathering mushrooms.

So, I might add, are the bears, so the wise human berry-picker makes plenty of noise!

The forest here can look pretty sparse -- spindly trees and a forest floor covered with tiny plants, mosses, and lichens. You'd think that by the time the big two-footers and four-footers were done harvesting, there wouldn't be much left for anyone else.

But you'd be wrong. A lot of little creatures depend on the foods provided by the boreal forest to make it through the long winter, and they're out harvesting too. If you look closely at the tiny plants that flourish beneath the trees and along the forest's edge, you'll find plenty of goodies to gather.

In the alpine, where forest gradually gives way to alpine tundra, pikas are building up their haystacks. A small cousin of rabbits, a pika can stash away 20 kilograms of grasses, leaves, seeds, and flowers over the summer, much of it in large piles just outside the entrance to its burrow. When the winter wind whips across the bare mountainside, driving snow before it, a pika doesn't have to go far for a snack.

Down on the forest floor, the voles are also tucking away winter groceries. They're less ambitious than pikas, and a lot smaller -- like tiny, delicate mice. Still, a single northern red-backed vole might store up to 3 kilograms of seeds, berries, and fungi near its winter burrow.

But voles and many other creatures of the forest floor don't just depend on food hoards all winter. When snow covers all that autumn bounty and the forest looks barren, many of the forest's smallest creatures are still out there, awake and busy.

They scurry around all winter under the snow, in an area called the subnivean zone where the warmth of the ground partially melts the snow above it. There, tiny animals search the buried vegetation or scoot through tunnels in the snow above, still harvesting frozen blueberries, bearberries, cranberries, rosehips, seeds, kinnikinnick berries, fungi, and all the other tiny jewels of the boreal forest's treasure chest.

If you'd like to know more about what people and animals are harvesting in the Yukon forest, Jozien has a blog called Yukon Wild Berries.

To find out more about the physics of the subnivean world, the Cable Natural History Museum of Wisconsin has a nice online article about Subnivean Temperatures.

And here's a nice article in the St. Albert Gazette (Alberta) about subnivean life a little farther south in the boreal forest.

Or you can check out the chapter about life in the cold -- "Ice is Nice" -- in my book Lizards in the Sky: Animals Where You Least Expect Them.

Best of all, go for a walk in the autumn woods, with your local guidebook and a berry bucket. Happy harvest!


No comments: