Fewer Fungus Among Us?
The family freezer holds an Alaska mix of store-bought and wild-caught foods, a ready resource for the span of feasts between Thanksgiving and New Year's. This year it's missing only one familiar standby; the freezer holds no native mushrooms.
The absence of wild mushrooms means little here. Crops of the local edible fungi vary greatly from year to year, and I'm a very conservative mushroom hunter, sticking only to species I can identify with certainty.
But elsewhere mushroom hunters' larders are empty because mushrooms are disappearing from places where they've endured for decades. European mushroom hunters report fewer species and fewer, often smaller, specimens than ever before. (That may be one reason why European buyers were so keenly interested in Alaska's outburst of morel mushrooms after the Tok forest fire).
According to Eef Arnolds, a fungal ecologist at the Agricultural University of the Netherlands, woodland fungus species are in a "catastrophic decline" throughout Europe. If that were true only for prized edible mushrooms like chanterelles or boletus, it would be easy to assume that they had fallen victim to overharvesting. Yet even so-called toadstools, inedible or downright poisonous species, are more scarce than they have ever been. Arnolds asserts that changing forest management practices are not to blame because fungal quantities and varieties have declined in all types of mature forest, no matter how the trees have been tended.
Arnolds' work, as reported in the journal Science, quantifies the decline in the Netherlands. Surveys carried out between 1912 and 1954 recorded an average of 71 species; surveys between 1973 and 1984 found an average of 38 species. During the past 20 years, the number of species in some study plots has gone down better than two-thirds, from 37 to 12 species per 1000 square meters.
Arnolds' colleagues agree with his findings. One mycologist, Johannes Schmitt of the University of Saarbrucken in Germany, has been weighing the wild mushroom crop sold in the local market every year since 1950. Both total numbers and individual sizes of the chanterelle and boletus mushrooms offered in the market have shrunk spectacularly. In 1975, it took 50 times as many local chanterelles to make up a kilogram as it did in 1958.
It would be easy to shrug off such statistics as bad news only for European devotees of wild edibles, but it appears that mushrooms in a forest may function a little like canaries in a coal mine. Their death is a sign of danger for other forms of life.
In this case, it means trouble for the trees. The vanishing fungi are generally those living symbiotically with certain tree species. Their fine subterranean filaments extend the trees' root systems, providing water and nourishing minerals in exchange for the trees' provision of carbohydrates. Trees that lose their fungal associates become more susceptible to all kinds of stress, from germs and drought to pollutants.
Of course, it may be that unhealthy trees can't provide well for their fungal associates. Possibly we can see symptoms in the annual growth of fungal fruiting bodies decades more quickly than we can in the slow growth of trees. Most probably, whatever causes the trouble makes both partners suffer, and feedback effects speed the demise of both.
Arnolds thinks the culprit is air pollution, since he has found strong correlations between the most polluted air and the most severe declines in mushroom populations for various areas of the Netherlands. If he's right, Alaskan mushroom lovers can breathe easy for now; in areas lying outside our cities, Alaska's air quality is very good---so far.
