By Joe Rankin
posted
Aug 9, 2012
illustration by Adelaide Tyrol
When we bought the old farm two decades ago, the Ghost Tree came
with it. He was an old sugar maple with a knothole face, tears in
the trunk and branch stubs. He looks like one of the Ents, the
walking trees in the Lord of the Rings movies.
The Ghost Tree stands at the edge of an old pasture, inside a
stone wall. Both sides of the road and driveway and adjacent stone
walls were once lined with his kin, probably planted at the same
time in the decades before the Civil War. It must have looked
impressive. Today, fewer than a dozen of these mighty maples are
left. Every few years we have to turn one into firewood.
We decided early on to leave the Ghost Tree alone. Massive as he
was, there wasn't a heck of a lot of good firewood there. He didn't
pose a danger to buildings or utility lines. His hollow trunk was
home to many creatures.And he was beautiful, despite the decay.
There are lessons here in impermanence and equanimity; also, a
firsthand look at how trees decay. Kevin Smith, a scientist with
the US Forest Service's Northern Research Station in Durham, NH,
told me that it can take a huge sugar maple like the Ghost Tree 60
to 80 years to decompose, from the time it really starts to go
downhill until it's a pile of humus.
Smith was a student of Alex Shigo, an eminent forest pathologist
who developed the "expanded concept" of tree decay: that trees
react to injury and decay by walling it off, or compartmentalizing
it. Humans repair injuries: bones knit, cuts heal, skin regrows.
Trees, faced with a broken branch or a scrape, use chemicals to
wall off the injury. Then the tree's outer living tissues grow
around it.
While the forest often seems peaceful and quiet to us, it can be
less idyllic for a tree. High winds, ice storms, gnawing animals,
woodpeckers, insects, people with heavy machinery. Rare indeed is
the tree that doesn't start collecting injuries as a sapling.
Some species, like aspens and birch, are poor compartmentalizers
and thus don't tend to live very long. Others, like sugar
maples, osage oranges, and giant sequoias "invest a lot in
chemicals to resist decay," said Smith. "But part of the beauty of
nature is that eventually some fungus or a group of fungi will be
able to break the defensesdown."
An unseen cloud of micro-organisms and fungal spores swirls
around every tree in the forest, waiting for their moment. First on
the scene of a wound are non-decay organisms hungry for sugars in
exposed sap. They're followed by bacteria and wood decay fungi
armed with special enzymes to break down cell walls to get at the
locked-up carbohydrates.
Decay can involve many types of microorganisms. Some work at the
same time, some follow one another. Some are specific to particular
species, others are generalists. They're often aided by insects,
animals, or birds. At some point, the tree can't summon enough
energy to take care of the living tissues it's responsible for, and
an inexorable decline begins.
The Ghost Tree has definitely deteriorated in the 20 years since
we became part of the scenery. When we first made his acquaintance
he had no top, but did have a couple of living limbs - each perhaps
18 inches or more through - that jutted out from the trunk then up,
and looked like arms. Combined with his "face," he looked like he
was perpetually startled by something he saw coming down the
road.
One arm dropped off a few years ago and the other is now dead.
More of the top part of his massive trunk has disappeared. He is
only a shell of his former self. The only green he wears is a toga
of Virginia creeper.
He's no longer a living tree since he has no leaves to process
sunlight into energy. But he's alive in another sense, Smith told
me. "If you count all the fungi, bacteria, and insects, and birds,
and whatever else uses a dead standing snag, you'll find that
there's more life associated with a dead treethan there is with a
sound, healthy, living tree."
Joe Rankin is a former newspaper reporter who lives in
Central Maine, where he writes on forestry topics, keeps 70 hives
of bees, does market gardening, and walks his dogs in his 70-acre
woodlot. The Outside Story is assigned and edited by Northern
Woodlands magazine and sponsored by the Wellborn Ecology Fund of
New Hampshire Charitable Foundation.
Tagged:
The Outside Story, Ghost Tree
