Vanishing forest

By: Patricia Janes


A long the rim of Earth's northernmost land-masses sits an ancient forest. Its mix of pine, spruce, and other hardy trees encircles the globe like a giant green halo.This interconnected web of trees, mosses, birds, and other organisms is called the boreal forest. It is the world's largest intact forest ecosystem--It's even bigger than Earth's tropical rain forests.


But many regions in the boreal forest are under assault. According to scientists, logging, mining, and oil and gas companies are yelling "timber," leveling trees more often than the forest can sustain. "In many areas of Canada, the rate of tree cutting is faster than the rate of regrowth," says David Schindler, an ecologist at the University of Alberta in Canada.

That spells trouble for more than just the forest. Trees absorb carbon dioxide gas, a culprit in global warming, or the increase in Earth's average temperature. Fewer trees could speed up this warming. Tree loss could also affect the survival of the billions of animals that call the forest home.

SENSITIVE SPECIES


Each spring, approximately 3 billion migratory birds that winter in South America or southern North America turn tail and fly northward to the boreal forest. Why do the birds--from white pelicans to dark-eyed junco songbirds--undertake the lengthy journey, which may span hundreds or even thousands of miles?

Although vast swaths of the boreal forest are losing trees to deforestation, the ecosystem is approximately 70 percent intact. "It is one of only a handful of ecological systems that's still largely untouched and unfragmented by humans," says Jeff Wells, a scientist at the Boreal Songbird Initiative in Seattle, Washington. Once the birds--famished from their long journeys--finally reach the forest, they feast on a rich smorgasbord of insects and fruits that have sprung to life following a harsh northern winter. The nourishment helps prepare the birds for a successful breeding season in the boreal forest.

Many other animal species also rely on the boreal forest for survival. For instance, woodland caribou feed on the lichen that blankets the forest floor. This complex plant is composed of a fungus and an alga that grow together, relying on each other for survival. "It isn't until forests are middle-aged--from 50 to 100 years old--that the forest develops the lichen species that the caribou like to feed on," says Schindler.

But rapid deforestation in many areas of the boreal forest is robbing animals, including boreal birds and woodland caribou, of their food sources and secure breeding grounds. "Human development has meant that we've seen a decline in certain animal species that rely on the forest," says Schindler. "Particularly under threat are large carnivores (meat eaters) such as boreal grizzlies, lynx, and wolverine."

TIMBER!


Why is the boreal forest vanishing? The forest is a rich mine of natural resources. "Every sheet of paper that people use has come from a tree--most likely from the boreal forest," says Schindler. But that's not the only reason why saw blades are whirring.

Beneath the forest's ground lies a treasure trove of minerals, petroleum, and natural gas. To extract these resources, huge stretches of North America's boreal forest are being razed.

In the 1940s, the boreal region in the Canadian province of Alberta covered an area two thirds the size of California. At that time, only two or three roads cut through the forest. Today, "development has been so rapid that you can't walk more than 300 or 400 meters (980 to 1,300 feet) without coming across a road or other track, where people have gone through with a bulldozer to test for the presence of oil and gas underneath," says Schindler.

HEATING UP


But leveling the boreal forest does more than destroy homes for birds and animals. It also contributes to global warming. Every tree photosynthesizes, or uses sunlight to convert water and carbon dioxide from the atmosphere into the energy the tree needs to grow. As long as a tree is alive, the carbon it absorbs during photosynthesis stays locked in its trunk and leaves. This helps remove carbon gas from the atmosphere so it doesn't add to global warming, explains Schindler.

When industries shave large areas of the forest, the ecosystem's ability to store carbon is sharply reduced. This could set off a string of catastrophes: As the amount of the heat-trapping gas builds in the atmosphere, temperatures in the boreal forest and around the globe heat up. The heat dries out the trees. A dry forest is more likely to catch fire than a healthy one. And when trees burn, they release the carbon they've been storing.