The evergreen! How beautiful, how welcome, how wonderful the evergreen.
—Jane Austen (1775-1817) from Mansfield Park, 1814
🌿 🌿 🌿 🌿
The day dawned gray and cloudy, the kind of mountain weather that often leads to dulled photographs, but it wasn’t raining, and it wasn’t cold. In fact, conditions were above average, and in Northwestern Oregon that’s a plus! We opted for a hike, and so Chris and I headed to Brightwood to hike a trail known mostly to locals.
At the muddy parking area, we shouldered our packs, and crossed a dry culvert into the dimly lit woods. The smell of evergreen spiced the air; a smorgasbord of intoxicating green fragrances that made me to breathe fast and deep for want of more.
In the distance, the sounds of the river were like a whisper. The woods were peaceful, almost too peaceful, and seemed empty of life. Of course, nothing could be further from the truth. Animal sign told of their comings and goings that revealed these woods are a busy place. At trailside, piles of dirt the size of cow pies revealed the ambitious work of the Townsend’s mole—the Northwest’s largest mole. Cedar trunks, with their numerous carvings were telling signs that the pileated woodpecker prospers in these woods. Non-animal signs told stories of their own like the wind-felled Douglas fir with its upturned root wad. What a sound this big tree must have made when it fell! Root wads, while not the most attractive sight, provide habitat for various plants and animals. Also notable were snags, both living and dead. They too are important in that they provide forage, shelter, and nesting sites for birds, bats, flying squirrels, insects, and other creatures.
Not far in to our hike, I saw something that stopped me in my tracks. Chris had gone on ahead, but came back moments later wondering what had happened to me. I showed him a Douglas-fir that was seeping heavy amounts of sap. Not the usual trickling sap we often see, but thick rivulets. It is what is called a “sap stream” or “pitch stream” that a Douglas-fir releases to usually combat insects, namely the Douglas-fir bark beetle (Dendroctonus pseudotsugae); a destructive wood-boring beetle that attacks trees weakened by drought, fire, and/or disease. While most beetle outbreaks are short-lived, the damage they cause is often significant, and can result in the loss of hundreds of trees.
So how do sap streams work? When a tree is under attack, it releases large amounts of sap that (if all goes well) plugs the insect holes, thus trapping and drowning the insect. If infestations are too significant, sap streams are ineffective, and the tree will die.
It was unclear what caused the sap stream. There were no dead needles in the canopy, and no sawdust to suggest an infestation. To my eyes, the fir looked healthy enough, as did its neighbors. What I did notice, however, was what looked like dirt in and around the sap. Unfortunately, it was too high on the trunk to look at more closely. So what had caused this reaction? Insect? Injury? Or was it something else?
I recorded my findings in my journal adding them to an ever-growing list of questions that might or might never be answered. On the ground lay a sprig of leaf lichen. I picked it up, attached it to my pack strap, and started down the trail.
Copyright 2013. All rights reserved.