|Home, Dead Home|
|Written by Jeff Shimonski -- BT Contributor|
A decaying tree can provide a wonderful habitat for wildlife -- just make sure you’ve got a place for it to fall when the time comes
When I drive home every day, I pass by a small, well-known plant and animal sanctuary. Something that always catches my eye is a very tall, dead, and still-standing pine tree.
It is probably 40 feet tall and has been dead for at least a couple of years. One of the things I do for a living is evaluate trees for their overall health and structural stability, so I can’t help but mentally measure the probability of this tree failing at some point, and wondering what its likely targets would be. A target is people, animals, or property that could possibly be struck and damaged if and when a tree, or parts of it, fail.
We all know that, at some point, a dead tree will fall down. So why are dead trees sometimes intentionally left standing (and did the property owner first check with his or her insurance agent)? The dead pine tree I mentioned easily could fall onto a well-traveled sidewalk or adjacent road.
Just this past month a superior court judge in California upheld a $7.6 million jury verdict against a city for not taking care of a palm tree that ended up toppling over in a storm in 2010, striking a man standing in his yard and paralyzing him.
The photo that accompanies this article shows a squirrel on the trunk of a dead palm, checking me out. She’s standing just below her nest, a hollow cavity in the trunk. This palm succumbed to the fungus ganoderma a couple of years ago and, since it is in an isolated section of my yard at home, I decided to leave the 25-foot-tall trunk as a habitat for wildlife.
My experience tells me dead palm trunks typically will remain standing a couple of years before they fall down under their own weight, but I check the stability of this one every couple of weeks. When I deem the trunk too unstable, I will just push it over. (That’s how I found out the squirrels had moved in; they got really fussy one day when I pushed on the trunk, rattling their home.)
Meanwhile I’ve been watching a series of animals nest in a single hollow on this trunk. A family of red-bellied woodpeckers first made the hollow and raised two babies to maturity. Next came a pair of screech owls that chased out nonnative starlings that had been checking out the cavity. That was really cool.
The owls raised three babies. I would see the family gather in neighboring trees in the evening once the babies fledged (grew wings and were able to fly on their own), at least for a month or so before they all flew off. After the owls came the squirrel family, which currently inhabits the trunk and has already raised a couple of offspring. I know this trunk will not last much longer, but it has been valuable as a wildlife habitat.
Dead trees are a big thing in wildlife conservation. I once read an academic paper published in a serious forestry journal on how to create dead wood and snags in the canopies of tall forest trees so birds would have more nesting areas. The paper described how students infected shotgun shells with various species of wood decaying fungi and shot the bullets into the upper trunks of trees. It was a very interesting read, but I’m not sure how successful they were.
Woodpeckers are able to excavate a cavity in dead and decaying wood for a nest and, after they have raised their brood, other species can utilize the cavity for their own purposes. This is why many people leave dead trees standing. My wildlife habitat palm trunk was an excellent example of leaving a dead tree for a “highest and best use,” and I plan to keep dead trunks standing in my yard as long as possible.
(I also utilize dead tree trunks to grow edible mushrooms. It’s not too difficult to inoculate the wood with the fungus mycelium, the stringy white or black threads that grow throughout the wood that are actually the body of the fungus).
But since I’m also aware of the serious consequences of a falling tree, I’m very careful about what surrounds these trees. If I owned or managed the property where that tall dead pine tree resides, I would have removed the top 20 feet or so of the tree, so when it fell, it would not reach the sidewalk or street and possibly injure people or damage property.
Those of you who have enough yard space to give native wildlife a home in dead trees, remember to keep an eye on what surrounds the tree, in preparation for the day it comes down.
Volume 13, Issue 1, March 2015
Art and science collaborate in “anthropoScene”
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