Alaskan Earthworms

The article on earthworms that appeared in this column in early October 1980 contained a regretted error. The mistake was the statement that northern forest soils were too alkaline to support earthworms. Ms. Lola Oliver of the University of Alaska's Forest Soils Laboratory correctly notes that these soils are acidic. Earthworms like neutral soil; they can handle slightly acidic or slightly alkaline soil, but not the more-acidic soil typically found in northern forests.

Also, thanks to Fairbanksan Bob Cummings, who has loaned me two books on earthworms) I've learned more about the topic. One book in particular, The Earthworm Book by Jerry Minnich, published by Rodale Press in 1977, is a goldmine of factual and interesting information.

Like snakes, earthworms are cold-blooded, so they slow their activity when the temperature moves toward the freezing point. Even those earthworm species that live at latitudes where the soil freezes are easily killed by sudden fall freezes unless there is substantial mulch cover to slow the freezing process. The earthworms evidently prefer some time to burrow deeply enough to stay below the frost line, but can survive the winter in frozen soil. Even so, one can be pretty sure that where there is permafrost there are no earthworms.

Of the 1800 known species of earthworms, Jerry Minnich says that the only recorded natural Alaskan is the species Bismastos tenuis, one of the smaller earthworms. He suggests experiments to see if the deep-digging (to 15 feet) nightcrawlers, Lumbricus terrestris, and the common field worm, Allolobophora calignosa could be successful introduced for the purpose of building garden soil. Bob Cummings is experimenting with both and says that earthworms found at Chena Hot Springs near Fairbanks are the common field worm species. Earthworms also occur at Pilgrim Hot Springs, near Nome.