conifer mystery on the Loup

[treeguy]

Many of the burnt trees have broken upper trunks. I thought that trees would first rot at or below ground level, and then fall. Any theories?

[moose]

Geoengineering

[BaublitzBurgars]

A tree is like a coral reef. The live part of the tree lives on the outside layer of the tree, always building out and up or for the roots down and outward. Underneath is the cellular dead structure left behind we call wood. So when the tree dies it is weakest where the underlying structure is thinnest-the top. It’s a design that allows snags to stand for decades. And think of how long it takes for the trunk to rot. I also have noticed the large roots are tight grain and often packed with resin which I’m guessing counteracts rot. So there’s my theory and probably some one can google and prove me wrong!
Len Baublitz

[Reapward]

Good question and theory.

Many trees behind our house from the 2015 fire and in Elbow Coulee have broken off at the height you are describing. They seem to weaken most there and then the wind does it's thing or have heard them come down even on a still day. A changed ecosystem for sure.
Or bugs do come in afterward and weaken them.

[WCC Tile]

Not a huge mystery, and I’m not a treeguy. But it seems that after the fire years ago, bugs found food in the dead trees, (above the intense heat level).
Then the perching birds (woodpeckers etc) found food (the bugs) and perforated the trees at the same elevation where the bugs were eating the tree where it was most beneficial for them.
Then the wind blew.

[george]

In older trees, cubic brown butt rot may begin to grow up the center of the tree. This fungus is brown because it eats the white cellulose and leaves the brown but weaker lignin intact. Trees can still live a long time so long as they don't fall over because the fungus operates mostly in the center of the trunk, but the rot will continues to grow either way, even after the tree is dead. This rot is common in Douglas fir, and you can see it working in the center of old stumps, some of which can be hollowed out to make drums. Eventually the butt of the trunk will decompose into a smudge of brown chunks of sawdust that are square in shape, hence the name cubic brown butt rot. Another name for this rot is crack rot because it predisposes trees to crack off above ground. Other types of root decay cause the tree to rot at the crown, and these trees fall with the root ball still connected to the trunk, e.g., laminated root rot. You can classify wood decay fungi into those that grown in the center of the trunk (heart rot and butt rot) and those that grow outside the roots, or you can classify them by whether they eat the cellulose or the lignin.

[Reapward]

Thanks George. Does this fungus get into older live trees? Have not seen that happening up here, only the burnt trees. I almost don't recognize the landscape.