As a Metro scientist, Kate Holleran sees nature's biggest challenges and most glorious surprises – and she has the muddy boots to prove it. Read her latest reflections on restoring the land protected by Metro's voter-approved Natural Areas Program.
By Kate Holleran, Metro Scientist
Conserving nature, one acre at a time
Sometimes the unexpected in the forest is so big, even I can't miss it.
Last week my colleagues and I walked up on a massive 6-foot-diameter, old-growth Douglas-fir. We were completing our field reconnaissance of one of Metro's newest natural areas in east Multnomah County, identifying the work needed to take care of the land. Four of us gathered around the big tree and began to guess its age: 220, 350, 400 years old? There were other large trees in the stand, many three feet or more in diameter, but very few close in size to the old Douglas-fir tree. This large tree was a biological legacy of the forest that once grew here.
Remnant old-growth trees that survived fires, logging and land clearing are scattered throughout Metro's territory. Forest science research indicates these large, old legacy trees have significantly higher species diversity than adjacent younger trees, meaning they provide habitat for a greater number of species and individual animals. In contrast to relatively simple conifers less than 200 years old, older trees have much more character. Centuries of out-competing adjacent trees and enduring winter storms, insects, diseases and the occasional fire have sculpted massive branches, deep bark crevices, broken tops, cavities in the trunk and fire scars. This diversity of form in one tree leads to a rich diversity in function. Many bat species use the fissured bark and tree trunk cavities as roosting sites, the wide, platform-like branches provide nesting sites for red tree voles, the thick crown shelters slow-growing epiphytes such as Oregon lungwort (Lobaria oregana) and literally hundreds of invertebrate species call old-growth trees home.
One tree, if it is in the right place, makes a huge difference. I think we¹ll just take care of the weeds on this property and let the forest grow old.