10/02/2011

Giant Fallen Douglas-fir Snag

The huge Douglas-fir snag took out a branch of a Bigleaf maple on the way down

On a recent trip up Sooke River road to Sooke Potholes Park to view spawning salmon, I noticed this massive ancient Douglas-fir snag that recently succumbed to the relentless pull of gravity. It looks like it probably made a sound - a big sound.

I am surprised I didn't notice this massive remnant from the ancient forest of days gone by before it fell. It is just off the road, and it is huge! The Douglas-fir had already lost its top which was nowhere to be seen. The 20 meter wind-snapped snag remained, and stood until very recently.


This tree was probably hundreds of years old when the top came off. The remains could have stood for another hundred years or more. During that time insects moved in creating pathways for other organisms that slowly eat and break down the wood. Beetles, sow bugs, termites, centipedes and slugs all came to the banquet.

Soft, decaying wood in large snags allows cavity nesting birds, like woodpeckers, to dig out comfortable homes. A spotted owl may have used the broken top to settle down in and raise a family. A squirrel family may have moved in after the birds moved out. The snag was a vertical ecosystem unto itself, hosting literally billions of organisms.

Having fallen, the snag changes status. Now it is 'large diameter woody debris', an integral component of old growth coastal forests. It will add to the forest floor for hundreds of years more as it breaks down further, providing rich nutrients and habitat for many more organisms.

Perhaps a salamander will discover and occupy the log. Salamanders have smooth, unprotected skin, that requires a moist environment. They don't like heat or dryness, so the fallen log is a perfect haven.

Slabs of thick bark
Decaying logs are sponges that soak up enormous amounts of water over wet coastal winters. During summer droughts the log provides the moisture that the salamanders need.

The tree's status may yet change again, as the log decays into the forest floor and tree seeds establish themselves on it. Then it will be known as a 'nurse log'.

When this huge snag fell, echos of the past resounded through the forest. It was a reminder of the change that happens constantly in intact forest ecosystems.

It was also a reminder of how humans have interfered in this process. Trees like this one are rare today due to our misguided intervention.

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