The Kodiak Treeline

A strange thing happens in Kodiak, although there are probably people who have lived there for many years and never taken particular notice of it. The peculiarity is that the port city lies exactly on the line of demarcation between the coastal spruce forests around the Gulf of Alaska and the treeless expanse of the Aleutians to the southwest.

It is possible to have a barbecue with your neighbor under towering spruce trees on the northeast side of town, and return home to the southwest side in the shadow of Pillar Mountain with nary a tree in sight. What's more, if you continued along the curving line of the Aleutians, you would 't see any more trees until you reached Russia's Kamchatka Peninsula, some 1600 miles to the west.

It is difficult to explain why Alaska's southeast panhandle supports some of the lushest forests in the world, while the Aleutians have none. Both lie in the same latitudes and receive the same amount of sunlight. Both are subject to weather that is windy and rainy, so why the difference?

As a matter of fact, ancient traces of forests show that the Aleutians once did support trees, but the last ice age of some 20,000 years ago put an end to that. Surprisingly, the glaciers did not cover interior Alaska, although the entire North Pacific coastline from the Aleutians to Washington State was buried under a load of ice up to two miles thick. When the glaciers pulled back, the islands were stripped bare.

Reseeding occurred in southcentral Alaska and the panhandle from small stands of forest that were left exposed during the glacial epoch and from the Interior, which was ice-free. However, Kodiak Island and the Aleutians were not so fortunate. Their chances for reseeding were slim because seeds could only come from the mainland, and the wind and weather patterns were against them. The new forests lay to the north and east, but the prevailing winds in the islands blow from the south and the west after passing over thousands of miles of ocean. Furthermore, dry weather is needed to scatter the seeds, and that is a rarity on the islands.

How those first seeds made it over to Kodiak is anybody's guess. Perhaps they were carried by birds or a drifting log. Maybe natives brought them along in cones.

At any rate, now that the forest has a foothold on Kodiak Island, it shows every indication of staying. Young and vigorous, it is marching southward at the rate of about a mile every hundred years. Given time, even the Aleutians will probably once again be forested. It is not that trees won't grow there, it is simply that they have never been reseeded. Spruce trees planted on the islands by the Russians in 1805 are doing just fine and reseeding themselves naturally, although the total tree population hardly amounts to a forest. In recent years, trees have been planted at military bases along the chain, and the State is now shipping out seedlings for reforestation projects all over Alaska.

Who knows? Some day in the distant future, there may even be an Aleutian State Forest.