Who would want an old, dead, standing tree, called a snag, in
their front yard? Answer: me, only so long as it wouldn’t land
on our house when the time came for natural forces to fell it.
Here is a perfect situation to recall the poem that George Pope
Morris wrote in 1830, "Woodman, Spare That Tree."
There was a time when it was thought that a snag was of far
greater harm than value to a forest. Why not plant a new tree in
its place? Perhaps lightning might strike this dry
"tinderbox" and spread fire to the rest of the forest.
Or maybe insects would use the punky old veteran in which to
breed, multiply, and infect other trees. I can easily imagine
our friend of past years, Miss Emma Toft, replying to all of
these worrisome thoughts with one of her favorite sayings;
"Don’t shake hands with the devil ‘til you meet him!"
Fortunately research has put an end, at least on paper, to
these and other somewhat inaccurate assumptions. Now, as
officially declared in U.S. Forest Service policy, land and
forests managers will, "through resource coordination,
provide the habitat needed to maintain viable, self-sustaining
populations of cavity-nesting and snag-dependent wildlife
species. This coordination will include the retention of
selected trees, snags and other flora, to meet future habitat
requirements."
There are about 85 species of birds in the U.S. that are known
to nest in tree cavities. This number includes house wrens, tree
swallows, bluebirds, woodpeckers, great crested flycatchers,
chickadees, nuthatches, screech owls and American kestrels.
Remove these birds from a forest and the trees may be in for a
great deal of trouble. European foresters of past years, such
as in Germany and Spain, learned that highly manicured forests
were not healthy forests. Today they spend thousands of dollars
annually putting up and maintaining nest-boxes while they
patiently wait for nature to take its course and eventually
produce dead snags. The very existence of the forest depends
upon various living creatures – mammals, birds, predatory insects
– for their role in protecting it from an unbelievably large
population of plant-eating insects.
We could very well consider an old standing snag as a wildlife
high-rise apartment. Blown to the ground it becomes a bungalow
virtually alive with dozens of insect species as well as small
mammals, worms and snakes. One has to marvel at that wonderful
complex of organisms, dependent, interacting with each other in
countless ways, living, growing, dying, disintegrating, the great
and eternal cycle of the woods, the living depending upon the
dead. Herein lies the very essence of biodiversity.
Enter an old-growth woods that has essentially remained
untouched and un-logged and you will witness biodiversity at its
finest. Among the leaders in the U.S. strongly promoting this
exciting concept is the new Center for Biodiversity at the
University of Wisconsin – Green Bay, directed by Professor Robert
Howe.
Each woods has a carrying capacity. A wildlife species, be it
a white-footed mouse, carpenter ant, red-eyed vireo or barred owl
can reproduce only to the extent that the forest can supply food
and shelter.
Many snags have provided me with dozens of memorable wildlife
experiences. For example I can vividly recall an ornithology
professor and his college students wanting to bet me and my
younger students $10, as we sat around a campfire at Wyalusing
State Park in around 1958, that we could go to the edge of a
certain river-bottom slough the next morning, sit patiently
observing an old snag leaning out over the Wisconsin river, and
see a pair of brilliant prothonotary warblers feed their young.
I had taken 14 of my sixth graders, our "fledgling"
bird club at Shorewood Hills School near Madison, on a three-day
camping/birding trip in early May to observe and study birds.
What an exciting time we had, camping, cooking all our meals over
campfires, and witnessing the spring bird migration at one of the
best places to do so in the entire Midwest. How fortunate it was
that I didn’t take up the professor and his students on their
proposed bet, because we surely did see the prothonotary warblers exactly as we had hoped!
The U.S. Forest Service recommends in general that two or
three good snags per acre should remain standing. Based upon
experiences in our own woods of around 17 acres, I like to think
that eight or ten snags per acre should be left alone. These are
old trees having a diameter of at least five or more inches.
Actually the bigger the tree the better. Fewer snags per acre
are needed if they are a foot or more across the trunk.
Examine the old standing dead trees in your woods carefully
before leveling them. Check for the obvious nest-holes, a hollow
base of the trunk, and other evidence of animal use. Remember
that a dead tree can be alive with birds and other wildlife.
Check your dead snags before removing them. Remember that a
dead standing tree can be alive with birds and other life.
This column appeared in the Door County Advocate
on 03/21/2003.
© Copyright 2003 Roy Lukes. All rights reserved.
