100_1228Winter lurks in the shadows on this late November day. I look up though the hardwood tree branches over my head and note that the sun is about as high in the southern sky as it is going to get on this chilly autumn day.  While my eyes are focused in an upward direction I notice the intertwining branches of a sugar maple and oak, growing too close for comfort.  Their naked and still form looks like a granite statue of two lovers embracing each other.  The pale blue sky, somewhat obscured by high thin clouds provides a peaceful backdrop to the branches that sway in the a light breeze.

I redirect my line of sight back to the forest floor.  The textures of bark are somehow more visible than they are in the summer.  Perhaps there are fewer distractions when the foliage of saplings and shrubs are not present.  The area of trees before me is really diverse.  There are black cherry trees with dark gray, almost purple, bark that is coarse and rough looking like old shingles on a shanty.  The bark on the white birch is mottled with dark gray patches; white thin papery strands of the bark flutter as a gentle breeze moves the air through the forest.  The sugar maple that is next to me has gray bark with deep furrows and ridges resembling streams joining together on a dry desert-like landscape.  The red oak that stands next to the sugar maple has even deeper furrows that line up vertically along the trunk pointing in an upward direction.  This tree has large, nearly round green patches of lichen interspersed over the southwest side of the tree trunk.  A mature black birch, about 20 feet from where I stand, has dark bark similar to the black cherry dashed with obvious horizontal lenticels.  This diverse section of forest also holds ironwood, yellow birch, red maple, white pine and hemlock; each with a different textured bark that makes up the forest collage.

Trees have unique adaptations that help them survive the bitter cold that will soon cloak the landscape.  Thousands of years of evolution have provided our northern forests with adaptations specific to cold climates.   Hardwoods loose their leaves by mid-autumn.  Scar tissue forms over the place where the leaf stem broke off lessening potential water loss.  Common sense would tell us that the loss of leaves stops the photosynthesis process, but some deciduous trees still do some photosynthesis in order to survive the winter through special cells that are located beneath the cambium of the bark.  Two trees that utilize this process are the American beech and quaking aspen.  Some birches do this as well. 

Conifers which are uniquely adapted to cold climates, also have significant adaptations that help them get through the long winter months.  Most conifers retain the majority of their needles throughout the winter months.  The needles are dark green and are photosynthetic on warmer, sunny days.  Photosynthesis can make an evergreen thirsty and water is not always readily available during the winter months.  The thick waxy coating found on most conifer needles conserves water by keeping the available water in the tree.  Extended periods of freezing also presents a problem for water movement within many conifers.  There are several adaptations that help with this.  The first is that many evergreens grow in groups.  Large areas of dark green trees act as a heat sink and can account for a microclimate where temperatures are a little elevated, particularly on the ground.  Another adaptation that some needled trees have is a system to maintain pressure within the water transport mechanisms of the tree.  When temperatures fall below 32 degrees farenheit the water within these transport tubes is frozen.  These transport tubes are called tracheids.. These tracheids have little check valves capped with a float (called a torus) that helps to maintain pressure within the water column.  When temperatures climb above freezing the water column is still continuous and can be utilized as needed by the photosynthesizing conifer.  Most conifers also have a single stem with branches that are wider at the bottom than the top.  This gives these trees the shape of an arrow which is critical in helping to shed snow loads after big storms.

As I turn and put my face into the wind that is coming from the northwest the sun warms the left side of my face.  The ground is covered with leaves.  Many are still brown and yellow but some have changed to the color of clay.  The light that filters through the overhead branches and strikes the surface of the forest floor highlights patches of individual leaves.  The checkerboard pattern of light and dark is fluid, morphing into moving shapes as the light breeze puts branches into motion overhead.  This movement is mesmerizing.  As I stare at the changing patterns it takes on a kaleidoscopic view of a lost summer. 

The breeze increases slightly and some of the leaves that have one end anchored to the ground from the last few days of frost make a rapid chattering sound.  The wind carries a pungent smell; deep dark earth exposed with the moving leaves. 

I want to enjoy the moment so I sit at the base of the sugar maple.  This tree is mature, about 20 inches in diameter, and the trunk holds steady in the increasing wind speed.  Before I sit I pull some leaves into a pile to cushion my rear end from the cold ground and make sitting a little more pleasant.  The leaf pile is compressed flat beneath my large body as I settle in.  The insulation value of this homemade blanket will be short lived.  As I rest my back on the tree I look up, once again, through the branches.  Spatters of light fall on my face as individual beams filter through the branches above.  The sky is now bright blue creating a majestic pattern of gray branches on a cerulean background. 

I feel at peace and can sense that I too am making a transition.   Like the forest around me I know that winter is about to begin.

 Written for in November 2009.

  • Ratty

    I really like the way you’ve given this lesson on the trees. I know a black cherry tree when I see one, but I’m still learning to identify the rest on sight just by the bark. This helps a lot.

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