Jerry Franklin was one of the first ecosystem scientists to visit Mount St. Helens after the eruption 20 years ago this May 18. Appearing particularly stark to the University of Washington researcher was the 125,000-acre blast zone, which looked like a moonscape, uniformly gray and, from initial appearances, sterile.
Investigations would, however, reveal that even in desolate-looking areas there were often what Franklin began to call "biological legacies" -- whole plants protected by snow, seeds, spores, root balls from which new plants could sprout, even downed trees as well as debris that offered footholds for other plants to take hold.
The importance of these remnants, the varied ways survivors and invading plants have both competed and depended on each other and the role happenstance can play revealed that classical studies of plant establishment were often too simple for what happens after major disturbances. Work at Mount St. Helens came at an important turning point in thinking about vegetation both for scientists interested in natural processes and for those interested in new ways of managing landscapes disturbed by human activities such as logging.
On and around the mountain, layers of snow and soil helped preserve plants and animals. At the higher elevations the relic sites were the size of a living room or smaller, according to UW botanist Roger del Moral, whose teams have worked at sites above 3,500 feet on the north side and above 4,500 feet on the south side of St. Helens.
One school of thought said the plants in those biological hotspots would colonize outward causing a re-greening of the area. Another said the red alderberry, slide alder, goatsbeard and other relic plants, many of which prefer shady conditions, would wither because the trees were flattened or obliterated in the blast.
But what del Moral and his fellow researchers found was that the patches tended to die back mainly at the edges. The exposed soil became a
Contact: Sandra Hines
University of Washington