Friday, November 25, 2011

Life of an Oak Part 4: the Eastern Forest Tree of Life

Life of an Oak part 4 of 4

After twenty or so years of slow continuous growth, the oak tree enters the next stage of life.  At this age most oaks begin bearing their first large harvests of acorns.  Ground fire disturbance during decades leading to mast production help the acorn bearing process along.  Native Americans knowing this would purposely burn oak woodlands to increase production.  While most oaks produce some acorns every year, years of large mast production typically happen every two or three years.  A few oaks, such as the White Oak, will only have large mast productions every five or so years.  Large mast production typically depending on spring weather conditions that affect pollination of the trees flowers.  During the spring flowering period for oaks, freezing temperatures will kill flowers or overly wet conditions will prevent pollination, both of which prevent large acorn crops from being produced.  Further complicating this matter is the fact that some oaks require only one summer to produce acorns such as White Oaks, while Red Oaks require two summers to mature acorns.

Mother of the Forest
Once mature, the open canopy of oaks allow flecks of sun to pass through the tree and across the forest floor.  Greater amounts of sun reaching the forest floor allows for a greater diversity of plant-live and
greater total plant production.  As a result, the oak tree not only feeds an abundance of animals with acorns in the fall, but by aiding thicker more diverse vegetation on the forest floor an abundance of organisms are fed through spring and summer.  Spring in an oak woodland is filled with a variety of delicate beautiful flowers such as Bloodroot, Dutchmans Breeches, Trillium, and Wild Geranium.  During the summer a thick green blanket of vegetation covers the forest floor.  Where oaks are more spread out such as in savannas or open woodlands even prairie plants can begin to establish themselves.  Other trees such as Maples have such thick canopies that forest floors under mature trees can often be quite bare.
These fallen pin oak leaves resist decay because of the chemical tannin within the.   By resisting decay and curling up like these leaves, oak leaves encourage low intensity ground fires in the fall.  
The Oak doesn't stop here however.  At the end of each summer and through early spring an abundance of dry curly leafs fall from the tree.  Other trees typically produce leafs that lay flat against the ground, absorb water, and rot quickly.  Oaks however produce hardy leafs that curl-up, resist decay, and remain dry.  These fallen leafs, as well as additional ground cover as a result of the oaks open canopy, produce an abundance of ideal fuel for a low burning ground fires. These fires clear forest floors, befitting both the oak tree and the overall community, as well as encouraging the growth of new oak seedlings.  And so the oak forest or savanna is perpetuated with its own help.

Cycle of Forest Life
The oak is truly a mother and nurturer of the forest, part of a larger cycle involving humans providing fire, wildlife being fed and dispersing seed, and the forest community being structured by the presence of this magnificent tree.  The mature mother oak produces an abundance of seed feeding forest wildlife.  Light is let through the tree canopy growing more plants that provide more food for wildlife.  Fallen leafs and thicker ground vegetation encourage fire that clears invading plants.  Forests cleared by fire encourage the tree to grow stronger and produce more acorns.  Wildlife, fed by the oak, disperse and plant acorns in new areas.  Fire in-turn produces ideal locations for acorns to sprout and grow into new oaks which will again nurture a healthy forest habitat.  And so the oak comes full circle.

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