Saturday, January 31, 2009

Fallen Giants

I, like most of you, have a list of blogs I like to read regularly. Two of my favorites are sectionhiker, by a fellow hiker from the Boston area named Philip Werner (on the boards he goes by Earlylite), and Ozark Highlands of Missouri, by an ecologist named Allison Vaughn. A few months ago Earlylite posted an entry about a book he had read called Reading the Forested Landscape: A Natural History of New England. I haven't read the book but it sounds facinating. Often as I'm hiking in the Ozarks I will look around at the forest and wonder "what happened here? why does it look different than it did a few miles back?" By reading Allison's blog I'm learning more about the ecology of the Ozarks and I'm learning to understand what I see better.

Here's a sight that I often see along the trail. A fallen forest giant that has had it's very roots ripped out of the ground.

This was a pretty common sight on my Middle Fork section hike. In fact in that post I showed a picture of my camp that just showed my bivy and tarp. But zooming back a bit you see that I was camped right next to one of these fallen giants.

In fact I was in between two of them. Here was the view looking out from my camp.

Natalie and I saw lots of fallen trees on our Buford Mountain hike also. At first I didn't know what to make of it. But after reading Allison's blog recently it hit me.

Here in Missouri (and all over the Midwest really) we occasionally have winter ice storms. An ice storm is where rain falls and freezes immediately on the first object it touches. The ice build up on limbs can be pretty heavy. In the city that means power outages. But within a few days the repairmen have come with chainsaws to remove the fallen limbs and trees and fix the lines. In the forest the trees just stay where they fall.

I think that's what has happened in these pictures. That would explain why it's the biggest trees that fell (even though they appeared to be healthy and not diseased). They tower over their neighbors and so collect the most ice. Then, if they are leaning slightly, that weight uses the long trunk of the tree as a lever and rips the roots out of the ground. That's how the forest removes the tall trees and makes room for new ones.

There's one more thing I wonder about though. Often these trees fall across the trail and then the trail maintainer comes through and cuts a chunk out of the fallen trunk so a hiker can get through. Often the trunk is hollow at the time. At least I guess this must be true because these cuts don't look very old.

I wonder what this means. Are all tree trunks hollow? Or does this indicate some weakening of the tree due to age or disease? I still have lots to learn about the forest before I really understand what I'm seeing.


Grant said...

Of course, the tree featured in your last picture does not appear to have fallen by itself. It got chainsawed, possibly because it was sick and rotting out on the inside.

My best guess: wood on younger trees is softer, perhaps because it is growing more quickly. Thus the wood on the inside of the tree (from when it was young) rots more quickly, whether it be while the tree is standing or after it has fallen.

I'd love to talk to a biologist and get a more expert opinion, though.

Heber Farnsworth said...

No, the tree fell because of the storm. The chainsawing happened afterward to clear the trail.

Philip Werner said...

I bet wind bursts could also be another reason for the tree falls. If you can, you should get a copy of the Wessels book I reviewed, either at Amazon or by inter-library loan. It is really an eye opener. Thanks for turning me onto your other favorite blog about the Ozarks. It is wonderful.

John said...

Most of the uprooted trees you see along the Middle Fork fell during ice storms in December 2006. Because of the shallow soil on the ridges and hillsides, the root systems of these trees don't have much to hold onto, and when laden with ice, the roots fail and the tree topples. It doesn't help that many of the black oaks in this area are stressed from oak borer beetles and recent droughts (which explains why so many are hollow and rotting; if you look close at the cuts you'll often see the 1/4" bore holes from the beetles).

The northern Middle Fork and southern Trace Creek sections were just trashed from the '06 storm. We sawed no less than 500 trees from along 20 miles of trail. If you look just off trail on some hillsides you'll see 50 or more uprooted trees in a single place.

There were also some high winds and even a tornado in the area in early 2006. We about wore out our chainsaws cleaning trail that year.

You can see the tornado swath on Goggins Mountain just south of Padfield Branch.