Douglas Fir Roots

Douglas Fir Tree Fall

As I was proceeding down the trail toward Carter Falls, I came across a recent tree fall. I thought it would be a good opportunity to demonstrate the root structure of the type of forest on Mount Rainier.

Douglas Firs can grow to be huge trees, upwards of 400+ feet (125m) tall and 15 feet (5m) in diameter.  Although this tree was not that tall, my crude measurements had it at about 150 feet (45m) tall before it fell.  To give you some scale, the tree sticking out to the left in this photo is approximately 6 feet (2m) off the ground.  That means that the main root structure to support this tree is about 15 feet (5m) in diameter.  When looking at the side view, you can tell that the roots for this tree are maybe 5 feet thick (<2m) at the widest.  


Side View of the Root Structure

It seems incredible that a tree that size can remain standing with that small of a base.  The reason that they don't fall over more often is that the roots of neighboring trees intertwine, forming a mesh that helps keep the trees upright.  Treefalls such as this usually begin a cascade of fallen trees because the support for all the roots are removed, making them much more unstable. 

In urban areas in the Northwest, it is understood that when a number of large trees are removed, the remaining trees are very susceptible to being blown down in wind storms.