Field notes: G is for girdle
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
"Did you bring black paint?" I asked my colleague Ryan.
We were marking trees for girdling or topping in one of our oak habitat areas at Chehalem Ridge Natural Area, near Forest Grove. Managed as a commercial tree farm for decades before Metro bought it, the property is dominated by fast-growing Douglas fir trees. They shade out Oregon white oaks, reducing the habitat for uncommon species such as Western gray squirrels and white-breasted nuthatches.
By girdling or topping the young but tall firs, we create snags – standing dead trees. Over time, the snags decay and provide food and shelter for mammals, birds and bugs. With a little bit of chainsaw work, we can give our oak trees more sunlight, which helps them thrive.
An orange paint mark of "G" means girdling (cutting partially through the trunk to cut off water and nutrients), "T" means topping (removing just the top of the tree), and "F" means falling (cutting the tree down). The black paint is for mistakes.
I marked a Douglas fir for girdling and then looked up at the top. The bole of the Douglas fir and the adjacent white oak tree appeared to merge into one trunk about 30 feet above my head.
Girdling the Douglas fir would result in a dead tree leaning against the white oak. With no way to fall the fir without hitting the oak tree, I needed to "erase" my orange G, hence the need for black paint.
We will let these two trees continue their competition for sun and space without our interference. May the best tree win.