Thursday, August 4, 2011

What Makes a Broadleaf Deciduous Forest: If I Were An Oak...

A mature White Oak.
If you were an Oak tree, where would you plant yourself?  This is not some flippant decision, planting an Oak  is quite a commitment.  As an Oak, you are committed to that spot for the rest of your 500 or so year life (if you are one of the few to survive).  Over the past weeks several entries have been on different types of Eastern Deciduous Forests found in Iowa.  This begs the question, why are eastern forests located in the east anyway?  So imagine: you are an Oak tree.  Where would you plant yourself?  Of course real trees can't plant themselves, they rely on gravity, water, wind, birds, or animals to carry seeds to hopefully ideal place to grow.  This process is sort of cruel in that greater than 99 percent of these seeds will die before growing to maturity, and of course I don't want 99 percent of my hypothetical trees to die.  Instead, imagine you are already a mature Oak tree and can plant yourself anywhere.  No irrigation or fertilizer allowed.  Since we are talking about the Eastern Deciduous Forest you can choose to be a White, Red, or Bur Oak.  You must choose somewhere you will be protected and have everything you will ever need for survival.  Plants aren't like animals, plants can't move around to find their energy and nutrients, everything must be obtained right where they are at.  This immediately excludes a lot of very scenic locations such as mountain tops.  Mountain tops just too windy and cold for Oak trees.  To answer this question we must first consider what our needs are as Oak trees. 

Bur Oak
White Oak

What an Oak needs
First, what is an Oak?  First, an oak has broadleafs.  This basically means large leaves, which are unlike conifer or pine trees that have needles for leaves.  Secondly, oaks are deciduous, meaning they loose their leaves in the fall and grow new ones in the spring.  So an Oak is a broadleaf deciduous tree, what are the requirements for this type of tree?  Well, growing leaves on an annual basis takes a lot of time, energy, and resources.  So we must plant ourselves in a location with a long growing season, plenty of sun for photosynthetic energy, and plenty of water and nutrients.  Deciduous leafs require plenty of water evenly throughout the growing season and can't have extremely hot or cold or dry conditions during the growing season, otherwise they fall off and the trees die.  So we can narrow our planting locations down to areas with stable moisture through the growing season and where temperatures consistently are warm but not too warm during growing season. 

Summary of broadleaf deciduous requirements
1. Long growing season, 2. Plenty of moisture through out the growing season,
3. Not too hot and not too cold during growing season, 4. Plenty of sun, 5. Good soil.
Red Oak
A desert has a long growing season and has plenty of sun, but lacks moisture, is too hot, and has poor soil.  The entire western half of the United States can be eliminated for these reasons.  Alaska might have plenty of moisture and good soil, but lacks a long growing season, lacks sufficient sun, and its too cold.  Almost all of the northern portion of North America can be eliminated here also.  This leaves the eastern portion of the United States.  Yes, I know, big surprise...  But why do broadleaf deciduous forests grow in the eastern United States?  The growing season is long, often six or more months a year.  Climate and seasons are very predictable, winter, spring, summer, and fall happen the same time every year and have consistent temperature and rainfall patterns.  Temperatures never get excruciatingly hot and never freeze during summer.  Rainfall is even throughout the growing season minimizing drought.  Finally, there is plenty of sun and good soil.
An oak forest
So you would plant yourself in the eastern United States, but lets be more specific.  You would also want an area protected from extreme fires so you don't burn down.  Oak trees can easily survive small surface fires but not anything larger.  Good soil is a must, so you would have enough moisture and nutrients.  Avoiding areas where their is too much water or flooding would also be important.  So based on these requirements, select a spot and plant yourself!  (Hypothetically speaking)

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