Forest Fires
Once again, it is forest fire season in Alaska, and this year, as in every other, fires are destroying growth in forest and tundra areas and occasionally threatening to destroy homes and property.
Each year during the past decade, forest fires have burned an average of 600,000 acres of forested land in interior Alaska. So the few tens of thousands of acres swept by fires during early June represent a small part of what is likely to burn before summer is over. During the 30 years between 1940 and 1970 the average forest area burned annually was close to a million acres, so there actually has been a decrease in average area burned this past decade.
The worst fire year of all in Alaska was 1940. That summer, fires raged over 4.5 million acres of forests in the Yukon, Tanana and Porcupine watersheds and on the Seward Peninsula. The years before that saw some sizable fires, also. In 1935, a single fire near Lake Iliamna burned 1.9 million acres. Other notable fires of that era were on the Sheenjek River in 1937 that burned more than 300,000 acres and the Mosquito Fork Flat fire along the old Valdez-Eagle trail that consumed 900,000 acres in 1922.
In 1915, sparks from a train at Chitina set a fire that burned nearly 400,000 acres. That same year, a woodcutter near Kennicott decided his work would be easier if he first burned over the tree-covered area he planned to cut. Things soon got out of hand, and before it was over the man had 100 square miles of dead trees to work on. Near Fairbanks, in 1926, a group of children set a tree on fire to dislodge a squirrel. Both they and the squirrel were soon in trouble when the fire spread to burn 38,000 acres. The next year another Fairbanks resident burned 5,000 acres of forest in an attempt to scare away bears that he said were muddying the water hole used by his horses.
Although man has set many of the fires that burned through Alaska over the years, most of the area burned--about four-fifths each year--is due to lightning-caused fires. Except in southeastern Alaska, where fires are rare, natural fire is an important part of life everywhere in the forest and tundra areas of Alaska; there are few areas that have not been burned during the last 200 years. Some forest areas burn as often as every 50 or 60 years, and trees older than 170 years are rare.
When a fire occurs, a new succession of forest growth begins, usually to end with the growth of tree types that were there before the fire. In fact, fire may be a requirement critical to maintaining stands of the most productive forest tree types--white spruce and birch. As these trees grow older, especially the white spruce, thick mats of moss build up on the forest floor. Unless fire comes along to destroy the moss, it eventually causes the development of permafrost in the forest floor, making it impossible for white spruce and birch to grow there. Then, these tree types may give way to stands of black spruce, hardy trees able to grow atop cold and frozen soils but which grow slowly and produce little wood usable for lumber and fuel. This is one reason why forest managers are inclined to let many forest fires burn, unless they are endangering people and their property.
