Such Beautiful Skin

Nov 2aa 015Fierce winds that went on for several days blew most of all the leaves on the trees to the ground.  Yesterday what few leaves on my big maple that survived the initial blow, gave up, floated down, and landed on my drive with an audible sigh.  I sighed too; November in Michigan is cold, blustery and unfriendly. My leaves usually fall over a period of weeks; this helps to get used to the idea that winter is not far off.  But that all at once drop got me to looking at what is left behind.  Tree bark-such beautiful skin. 

Nov 2aa 003The bark of this linden is comprised of a number of layers-the outermost layer, or cork, is comprised of cells that are no longer living.  This cork protects a tree in much the same way that skin protects people.  The bark slows the loss of water from the interior living layers of bark.  It is a deterrent to insect invasions, fungal and bacterial infection, and damage from animals. 

Nov 2b 005My skin surely reveals the amount of time I have spent outdoors; the trees are heir to all manner of insult from the environment that goes on non-stop. My corgi Milo has been trying to chase our resident squirrel up the trunk of my maple for three years now.  His toenails have grooved the bark, but not damaged the tree.  The variation in the appearance of tree bark makes it possible to identify trees by the bark alone; the diversity in plant forms is amazing. Old bark is beautiful in its texture and color. Rough, smooth, patchy, furrowed, scaly, exfoliating-we have so many words to describe the characteristics of bark.

Nov 2b 017The bark of a tree can be a host to all manner of mosses and lichens; some relationships are symbiotic.  Other plants such as mistletoe, are parasites.  Bark also protects a tree from sun scald, and frost cracks. In the summer, the horizontally held leaves of my maples protect its bark from sunburn.  Lacking leaves, freezing and thawing in the winter can crack the part, and expose the inner living layers to pathogens.  This big leaf linden conditions has many frost cracks which have just begun to heal. 

Nov 2b 001This old crabapple reveals many scars-some from pruning, some from insects-some just a result of age.  The appearance of the bark is an important element in the selection of trees for the landscape.  In Michigan, bark is the prominent visual feature of a tree for the better part of six months. The climax beech maple forests in the upper peninsula of Michigan are breathtakingly beautiful-as are the old cedars, and birches.  The trees are so old, large and tall, most of what you see is all that gorgeous bark.

Nov 2b 012The Popples, also known as Aspens, have very beautiful smooth bark that has a decidedly greenish cast.  Its sepia colored ridges and furrows are equally as attractive.  The stands of poplar trees on the slopes in Aspen are my favorite part of that landscape.  Bungeana pines, old Kousa dogwoods, and London Plane trees shed their old bark; this process known as exfoliation is incredibly beautiful.

Nov 2aa 025The bark of a tree will callus in response to a grave injury.  This linden was struck hard by a careless driver; five years later it is still alive and thriving, though its woody interior is exposed on over one half of its trunk.  The thickened bark is a healing response.  Some bark grows thick enough such that it can be carefully harvested from a living tree use; this we call cork.  The bark of the sequoia tree can grow as much as two feet thick-a proper scale for a tree of such great size. 

sept12 030Though the bark  protects the life of a tree, it does not protect forever.   Like people, trees have a lifespan.  This very old maple is in serious decline, partially from age.  Trees with limited life spans may not be a good choice for a landscape you hope to have a long time.

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Fungus has managed to invade this maple via a crack in the bark that could not heal.  This fruiting body of the fungus is a sure sign the tree will not survive much longer.  But given how long they usually do survive and prosper, careful thought as to the selection and placement of the trees will benefit the landscape.  Late fall is the perfect time to observe, enjoy, and plan around the beauty of the bark.