Thursday, May 5, 2011

McDowell Grove Forest Preserve

Fallen Limbs at the Forest Preserve in Spring
I took a walk in the McDowell Grove Forest Preserve by my house today. I had never been to this area before and I'm so glad I visited for the first time in spring. There weren't any real flowers to speak of but the floor was a carpet of green. I know in a few months, I won't be able to walk through the fields like I did today because the grasses and under story brush will be too high.  

There were fallen branches everywhere, creating a natural clearing. I don't know if it is normal for so many branches and trees to lie on the the forest floor or if there was some event that caused the branches to fall. One fallen log had a reddish moss growing on it but the majority did not. I wonder what was different about that log - the age, type of bark, moisture content of the wood? I'm guessing the latter, but I'd love to bring an ecologist to find out next time.

Pools of Algae from a Flooded River
As I walked a little further into the forest, I noticed that the adjacent DuPage River has been flooding into the forest floor. Flood stress over time could be what caused the the downed limbs and trees.  The flood waters were interesting.  In urban environments, we rarely get to witness how nature responds to floodwaters.  At the flood's edge, pools of water with rippling centers and stagnant edges play host to algae.  In the rippling water, the algae takes the form of thin filaments like threads flowing through the water.  In the stagnant water, fluffy pillows of algae obscure the view below.

While on my walk, I started to think about how this environment responds to the life's principles I've been learning about in my class.  The floodwaters made me think of the "Adapt to Changing Conditions" principle. Clearly the river floods repeatedly - likely almost every year.  The trees in this area must have adapted themselves to this condition or they would not have survived.   My tree classification skills are rusty, but I'm fairly confident that the tree mix was of elms, maples, and birch trees, among others.  Each of these tree species are somewhat tolerant to flooding but a particularly prolonged flood would cause root die off, and consequently limb damage or tree death.  This diversity of species will help the system maintain itself if one species is more susceptible to flood damage.  But the loss of limbs also aids in the system renewing itself.  The trees and limbs decay, host insects that return nutrients to the soil for new limbs and leaves to be created from the old.  This continual self renewal allows the tree and the system to maintain its integrity.

More photos, just because it was fun to take my walk today.  Next time, I will bring a better camera than my iphone.
Tree Decay 
Flooded Tree Roots
Downed Limbs in a Forest of Trunks

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