Field notes: The art of snag creation
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.
Conserving nature, one acre at a time
"How does 50 feet sound?" Scott Hyde asked, surveying the trunk of a Douglas fir. We were soaking in the rare December sunshine at Metro’s Chehalem Ridge Natural Area. "Sounds good," I said. No sooner than I had agreed, the gaffs of Scott’s climbing spurs bit into the bark of the tree. His gear included a climbing harness, rigid spurs encasing his lower legs and a flip-line. I knew as I watched him smoothly toss the line around and up the bole, removing and re-inserting his spurs, that he was at home in the arboreal world.
This work is part of a long-term restoration strategy for the 1,200-acre natural area near Forest Grove. Scott was topping a Douglas fir tree, which was competing with an Oregon white oak. Oregon white oaks are a rare habitat in the northern Willamette Valley, and they’re often shaded from the sun by younger but taller Douglas firs. Cutting the tops off the tall firs or girdling them (removing the cambium layer in circles around the tree bole) eliminates the competition and creates a valuable habitat feature in the forest: snags.
Snags, or standing dead trees, are important ecological features in our forests. For those of you who like numbers, they are notable. In Pacific Northwest forests, more than 100 species of amphibians, reptiles, birds and mammals use snags to feed, rest, roost, breed and find shelter. But human use over the last 100 years has resulted in a significant reduction or removal of snags from the landscape. Chehalem Ridge Natural Area exemplifies this condition. For decades most of the natural area has been farmed or logged, resulting in forests less than 25 years old and very few snags.
I spent the day watching Scott, our contractor, climb up to 60 feet high, cutting off tops (some more than 30 feet long), girdling tops (so only the top dies), or girdling trees at the base so the entire tree becomes a snag. Technically, I was directing Scott on the trees to cut and which technique to use. But in truth, he was the expert; he’s spent more than 20 years creating snags in public and private forests. He often suggested methods that both protected our oaks and made the condition of the newly created snag better for wildlife – by leaving forked trunks, branches with small nests abandoned for the season and perching branches.
At the end of the day, as Scott gracefully rappelled down the last tree with his chainsaw dangling behind him, I imagined the oaks stretching out their branches into new wide-open growing space.