Root Rot in the Evergreen Woods

Today I was walking along a trail through the woods near Evergreen State College. I came to an area where I noticed many large windthrown Douglas Fir trees, some ripped out of the earth at a snapped-off root crown , some with trunks cracked and broken a couple of feet above the ground. There was a gap in the canopy above me. I poked around some stumps and noticed cream colored mycelial pockets and white mycelial fans growing just beneath the top layer of bark. The roots themselves where rotted to a white spongy texture and were riddled with little holes. I looked around and noticed many other trees leaning to varying degrees, some a little bit and some quite a lot.  After inspecting all the trunks  I found conks of Fomitopsis cajanderi, a sometimes pathogenic and often saprobic fungus. But I don’t think this fungus was the culprit that rotted the roots of these mature Douglas Fir trees. This fungus probably colonized the log through stem and branch wounds soon after the trees fell. Noting the cream colored pockets of mycelium beneath the bark, the white spongy rotten roots riddled with small holes parallel to the grain, and the lack of any noticeable delamination of the wood I think Heterobasidion annosum is the root rot fungus present at this spot.