Wednesday, July 13, 2011

I fell for this tree

I went for a walk in the Morton Arboretum today, looking at tree bark. Yes, tree bark. For my biomimicry coursework, I have certain prescribed iSite assignments where I go out and observe nature. One of them included looking at tree bark and the differences between different species. This was on my mind after a conversation I had with Dr. Robert Fahey, a forest ecologist on staff at the Arboretum, about tree bark and its (marginal) insulative values. He spoke about Oak forests and how the rough bark fissures that Oak trees present actually create air pockets that help insulate the tree from fire and extreme cold.  It's cork-like texture also traps air pockets, adding insulation.  He was quick to mention that the cell structure of the live phloem has more to do with a tree surviving cold than the dead bark, but it was an intriguing idea for me and I resolved to contact a plant physiologist soon.  Dr. Fahey spoke about the the chemistry of bark and how some species create chemicals in their bark that protect the tree from predators.

Sketches from conversation with Dr. Fahey
But back to this tree that I love. The species is called Katsura (cercidiphyllum japonicum - another reason why I love the Arb: every tree is labeled!). The structure of this particular tree reminds me of Fred and Ginger, Frank Gehry's Dancing House in Prague, or dancing lovers the way the trunk splits off and intertwines. The bark of the tree dances in a pattern that weaves back and forth, overlapping and forming a gorgeous pattern so unlike any other tree I saw today. And the heart-shaped leaves grow in clumps like a Quaking Aspen or a Redbud. Simply beautiful.  Ok, so I'm a tree hugger. Everyone knew that already.

Katsura bark pattern
Tree bark, compared:
(Blogger REALLY needs a table function or I need to figure out a way to hack one.)

American Elm
The American Elm is a gorgeous tree.  No doubt about it.  It's branching structure that resembles a vase of flowers make it easily recognizable.  So is its bark.  The ridges, while they sway and flow with the tree, are linear and deep, likely to channel water down to the base of the tree.  The texture is rough to the touch.
Weeping European Beech
The Beech tree is the opposite of the rough Elm. It is smooth and flat with no ridges except for imperfections and scars.

Chestnut Oak
The Oak tree bark is not linear like the Elm nor smooth like the Beech.  It is rough and clumped and reminds me of the dry skin called "cradle cap" that formed on my newborn son's head.
The Maple tree is close to my heart because I have a beautiful old maple tree as the centerpiece of my back yard.  The bark is not as rough or deeply fissured as the oak and lichen are able to grow over its ridges.  I wonder what it is about the chemistry of the Maple bark that allows this plant to thrive on it?  It must be more than a structural reason because the smooth beech didn't have lichen growing on it.

I took many more photos of different trees, but I'm overwhelmed with bark right now and am stopping.  I may go back in the future and do bark rubbings to see if I have missed any observations that they could provide.

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