Mission Statement

Bearing Witness to Local Natural History-- from the wildness of Indiana

Saturday, November 10, 2012

The Colors of Autumn

Autumn is gone. The colors this year were unexpectedly spectacular after the drought this summer. I noticed the last leaves on many of my trees at home have fallen after today's wind.

I thought I would share autumn scenes from October since today was a warm reminder (60+ degrees) of just a few weeks ago. 

It is fascinating how leaves change color. There are three types of pigments present in leaves. Chlorophyll gives leaves their basic green color. It is necessary for photosynthesis. This is the chemical reaction that enables plants to use sunlight to manufacture sugars for their food. Trees in the temperate zones store these sugars for their winter dormant period. Carotenoids produces yellow, orange, and brown colors in such things as corn, carrots, and daffodils, and bananas. Anthocyanins, which give color to such familiar things as red apples, blueberries, cherries, and strawberries. These are water soluble and appear in the watery liquid of leaf cells.
Both chlorophyll and carotenoids are present in the chloroplasts of leaf cells throughout the growing season. Most anthocyanins are produced in the fall, in response to bright light and excess plant sugars within the leaf.  During the growing season, chlorophyll is continually being produced and broken down and leaves appear green. As length of night increases in the autumn,  the production of chlorophyll slows down and then halts. The carotenoids and anthocyanins present in the leaf are then revealed to show their colors.

A succession of warm, sunny days and cool, crisp but not freezing nights seems to bring about the most spectacular color displays. During these days, lots of sugars are produced in the leaf but the cool nights and the gradual closing of veins going into the leaf prevent these sugars from moving out. These conditions-lots of sugar and lots of light-spur production of the brilliant anthocyanin pigments, which tint reds, purples, and crimson. Because carotenoids are always present in leaves, the yellow and gold colors remain fairly constant from year to year. The amount of moisture in the soil also affects autumn colors

Certain colors are characteristic of specific species.

Oaks > red, brown, or russet

Hickories > golden bronze
Aspen & Yellow-Poplar > golden yellow
Dogwood > purplish red
Beech >  light tan
Sourwood > crimson 
Black Tupelo > crimson

Maples differ species by species.
Red Maple > brillian scarlet
Sugar Maple > orange red

Elms shrivel up and fall showing little color but dull brown.

When the leaves fall they are not wasted. They decompose and restock the soil with nutrients. Fallen leaves become food for many soil organisms vital to the forest ecosystem and the ecosystem of your yard and land! You can benefit your yard by not raking all the leaves that fall and allowing them to enrich your soil.

The seasons change and beauty of each one enriches my life. Adventures await with the coming of winter-- the cycle continues.

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