How to Change a Biome – Just Add Heat

If someone mentions the word tundra, usually you will think of an image such as this:

colin grice [CC-BY-SA-2.0 (http://creativecommons.org/licenses/by-sa/2.0)], via Wikimedia Commons

Very cold, lots of snow, very little vegetation. Yet, increasingly, researchers are seeing tundra that looks more and more like this:

Image Credit:BC Forbes, University of Lapland, Finland

This is an area of tundra called the Eurasian tundra and it is located between Finland and western Siberia. Siberian tundra was historically considered to be one of the most extreme environments on the planet, with temperatures ranging between -34ºC (-30ºF) and 12ºC (54ºF). Annual rainfall is usually less than 25 cm (10 inches). Those are shrubs in the pictures, but whereas the shrubs of the tundra are normally very small, the shrubs of the Eurasian tundra are now small trees. Show how does tundra turn into a small forest? Simple, just add heat. The diagram below is from the Biology 11th edition textbook that I co-author with Dr. Mader. If you can a look at the top of the diagram, you will see the basic characteristics of tundra (cold and dry).

Mader/Windelspecht Biology 11e 2012 – used by permission

Now, if you raise the temperature by 5-10 degrees Celsius (downward on the chart), and keep the precipitation relatively steady, you enter into a biome called the taiga (sometimes called a boreal forest). Taigas are characterized as slow growing northern forests, often with poor soil and low annual precipitation. The conversion of arctic tundra to taiga is the result of global climate change. And the changes show above are just the beginning. Some researchers predict that the annual temperature of the tundra could increase by almost 9ºC, which has the potential to convert a tundra into a woodland (especially in the southern regions). So why should we care? On the surface ad least, it seems that converting a low-productivity environment, such as tundra, into a more productive woodland is not really a bad idea. But the problem lies in the snow cover.

The tundra regions reflect a significant amount of the incoming sun’s radiation back into space, but plants (especially trees) absorb incoming radiation. While they do conduct photosynthesis, a significant amount is released as heat. And heat is the last thing we need on the planet at the moment.

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