By Katrina Marland
If I say the words “Arctic tundra,” what comes to mind? Winds whipping across a cold and barren plain? Though tundra is cold, it’s also home to a number of unique species of flora and fauna specially adapted to its harsh conditions. It only appears barren because of its lack of trees — one of the tundra’s defining characteristics. In fact, the word actually comes from a Finnish term for “treeless plain.” So although the tundra may be a complex and fragile ecosystem in its own right, one thing that it does not have is trees … or does it?
As Michelle wrote a couple weeks ago, climate change is already causing forests to migrate. For the most part, we are only starting to understand what this will mean for our forests. We know that native ranges will change, that some species will be more vulnerable than others, but we are only beginning to piece together a detailed picture of what these changed forests will look like.
In Alaska, nature isn’t making us wait. Researchers at the tree ring lab at Columbia University’s Lamont-Doherty Earth Observatory have completed a new study showing that although Arctic warming is affecting much of the world’s forests negatively, some trees are actually benefiting from it. Researchers analyzed the rings from living, dead and fossilized white spruce trees along the border of Alaska’s northern tundra, including the Arctic National Wildlife Refuge (see Amanda’s recent post on this important sanctuary). The patterns of the rings helped them compile a climate record going back nearly 1,000 years, and using this timeline, they found that the trees in this region have been on a steep growth spike for the last century, particularly in the last 50 years.
Temperatures in the far north have been rising at a rate several times faster than those in lower latitudes, giving the trees a longer growing season than they are used to. As the trees grow and the forest expands more rapidly, the treeline is moving slowly north, into the tundra. This might seem like great news for the forests, but for the tundra, the rising number of trees and shrubs are disrupting some of the existing flora in that range, which in turn affects the other plants and animals that depend on those species.
So is this good news or bad news? Some trees are thriving despite the effects of warming temperatures, which is great to hear amidst all the problems that climate change is causing for our forests here in the U.S. But at the same time, we’re talking about drastic warming in a climate so cold that it enjoys an average temperature of just 10 or 20°F, and winter temps of -30°F — and I find that a bit unsettling.