There’s a lovely stretch of the Mashel River, just a few miles above its confluence with the Nisqually, where several old growth trees still stand along the bank. Land Trust volunteers have helped clear Scotch broom and blackberry, and plant native trees and shrubs along shoreline nearby. This is a great spot for contemplation and once the habitat work is done for the day, we always spend a little time just sitting on the riverbank, watching the water flow by.
Last February, after a morning of planting trees, we started to talk about one particularly huge Douglas-fir on the opposite bank. The sort of tree that would take at least four people to reach all the way around – more than 5 feet in diameter and about 250 feet tall. We noticed that the bank was being rapidly eroded, exposing the roots. We mused about the earth shaking event that was destined to come, and how we’d love to witness it from a safe distance.
Sometime in the past few months, this event has come to pass. This ancient tree fell directly across the river, spanning from the opposite bank to the bluff on the Land Trust side of the river. With little sign of damage to the trunk, I imagine this log will be here for quite some time.
Events like this have the power to change the course of rivers, and I immediately began to fret about all the trees we’d recently planted downstream of this log. I knew that we were planting in a channel migration zone, but the reality of that didn’t sink in until this tree fell. The area that we planted may end up underwater or scoured away, so I will have to rest assured that Scotch broom can’t grow in those conditions.
Although the life of this ancient tree may be over, its role in the ecosystem is far from finished. It will most certainly collect logs and debris and create new and diverse habitat features for years to come. Over time it will continue its journey down the river, adding nutrients to the water and food for insects and other animals. For the short term though, this will definitely be my favorite lunch spot!
The importance of large logs in river systems has been well documented in recent years and in some places it’s necessary to design and install engineered log jams to increase instream habitat complexity where there are few opportunities for natural log jams to develop. In places where large, old trees still grow along the shoreline, sometimes we can just let nature take its course.