Lessons from Travels: Trees vs. Permafrost

by Carl Strang

Last week I contrasted our local trees with those of Australia. This week I want to go in the opposite direction, contrasting our forests with the lack of them in the far North. I did my graduate research in western Alaska, on study areas close to the Bering Sea. That area is a patchwork of habitats, but today the focus is on the upland tundra.

Upland tundra from the air. There were no roads where we were, and the only ways in are by plane or a very long boat ride.

On the ground, an upland tundra landscape looks like this:

The area behind the bluffs at Kokechik Bay.

Note the fine-grained pattern of colors. The ground is covered by a diverse mix of mosses, lichens, and dwarfed shrubs and herbaceous plants.

In this frame are cloudberry plants, mosses, at least four kinds of lichens, and at least two kinds of dwarfed shrubs. By the way, mature cloudberries are among the most delicious I have ever tasted.

The plants are kept small in part by the brevity of the growing season, combined with the severity of winter. That last factor is made clear by occasional patches of shrubs reaching two to three feet in height, where breaks in the topography accumulate snow which shelters the plants from the cutting winds (you can see an example in the top photo, the dark patch at the edge of the lower, grassy area which is an intermittent lake bed).

Another limiting factor is permafrost. Even at the height of summer, if you dig down you will reach permanently frozen ground less than two feet below the surface. Tree roots could never penetrate it. The soil also churns slowly but with great force in winter.

Cemetery at the abandoned village of Old Chevak. The dead cannot be buried. Their coffins would be crushed, and the bones and wood fragments brought to the surface, by the churning compaction of the seasonally freezing ground.

Tree roots similarly would be destroyed by this process. If you go inland you eventually begin to find trees. This makes for a common joke when towns are at the edge of the tree line. The following sequence of photos provides the example at Bethel, the dominant city of the Yukon-Kuskokwim Delta.

Bethel National Forest, entry sign.

"Bethel National Forest"

And the joke is complete.

There will be many future chapters from western Alaska in this series.



  1. jomegat said,

    November 9, 2011 at 7:45 pm

    Today is a good day to not be in western Alaska. I read that the storm they’re having now is the worst since 1974.

    • natureinquiries said,

      November 10, 2011 at 6:58 am

      I heard about that, and that the impact is worse because sea ice forms later now and is not there to dampen the waves. The fact that I was there in the summers of 1971-74 illustrates how rapidly climate is changing.

      • jomegat said,

        November 10, 2011 at 9:23 am

        I loved the National Forest gag BTW. 🙂

  2. December 5, 2011 at 7:13 am

    […] it. After all, I had lived in what I regarded as the real thing, when I conducted my thesis research in western Alaska. To my way of thinking, any tundra south of the great treeline of the North could not be anything […]

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