Mt. St. Helens: a wildlife laboratory
Mt. St Helen's ash fallout has been hard on crops, livestock, and machinery. What about wildlife? In the immediate area plants, animals, and insects were destroyed or forced out, as would be expected. However, farther afield, effects are showing up that indicate scientists have an opportunity to study some of the subtle aspects of environmental damage and recovery which are part of the ecological development of this volcanically active region.
For example, A. R. Gittins, an entomologist at the University of Idaho, finds that the ash is decimating honey bees by clogging breathing pores and abrading their waxy outer skin coating. Even when rain cleans off plants, ash is soon in the air again when it has dried. Workers returning to a hive can contaminate the whole colony.
Commercial honey bees are not native to North America. Nevertheless, the readily observable effect of ash on them does suggest that other insects, which are native, would be similarly affected.
Indeed, Don Scott, also of the University of Idaho, says populations of yellow jackets, grasshoppers, and some weevils and moths will also probably be reduced. Hundreds of small weevils, for example, have been seen kicking helplessly in the ash. This could be beneficial from a human viewpoint, since these insects are considered pests. Meanwhile, Roger Akre of Washington State University has found that worms, slugs, and some of the large ants (which sink in the ash, whereas small ants run on top of it) are also bothered. Substantial numbers of slugs, especially, have died -- confirming the old garden wisdom that a barrier of ashes will keep out slugs.
Effects such as these on insects, which are key links in many wildlife food chains, suggest how far-reaching the volcanic impact can be. Wildlife experts do expect the area to recover. The Mt. St. Helens Federal Coordinating Office notes that, while heavy ash has slowed plant growth, most plants seem able to poke through several inches of overburden. This suggests that wild habitats can restore themselves.
In the devastated zones, natural restoration will take considerable time but could begin soon. Grass and weed seeds should arrive with the wind. And, although it will take centuries to regrow the forests, a ground cover should spring up relatively quickly. Small rodents are likely to move in rapidly as grasses and bushes take hold. And, when they arrive, they should find insects for food awaiting them, since insects move back into such areas even faster than mammals. Birds and larger animals will likely follow. Although populations of some seed- and insect-eating birds have thinned out and many waterfowl and game birds have abandoned nests, there should be enough of them in surrounding areas to restock the region.
Thus, over the long run, scientists have gained a natural laboratory in which to study the re-establishment of a wild community in a volcanically devastated zone. It could be a replay in miniature of the kind of development that has produced the rich land and timber areas of the Pacific Northwest.
