Monday, October 10, 2011

Fall in the Eastern Deciduous Forest

Fall in the Eastern Deciduous Forests has to be one of the most dramatically beautiful events of any ecosystem in the world.  With fall, a series of events take place that begin the transition to winter.  Thick green of late summer, growing from canopy to forest floor, slows with shortening daylight and cooler temperatures.   With less daylight, chlorophyll which normally colors leaves green begins to breakdown.  As it breaks down, colors normally hidden by the green begin to express themselves.  Bright yellows from carotenoids in ashes, reds from anthocyanin in maples, and browns from tannins in oaks.  Red and yellow pigments breakdown even further and the leaves turn brown and fall to the ground.  These leaves form a layer of mulch across the forest floor, insulating the ground through winter, protecting plants, seeds, and animals from extreme temperature changes.  In spring, the leaves decay returning nutrients to the soil and fertilizing plants and trees in spring.
Normally green leaves gain their color from chlorophyll.  But when daylight decreases in the fall, chlorophyll breaks down and other pigments are shown, changing the color of leaves.
Hickory leaf colored yellow by the presence of carotenoid pigments.
Maple leaf colored orange by anthocyanin pigments.
But to pretend that brightly colored leaves are the only thing happening in the fall is far from the truth.  Not only do leaves fall from the trees, but an abundance of nuts also.  Acorns, Walnuts, and Hickory nuts fall to the ground providing "bread from heaven", fattening forest creatures up for the coming winter.  These nuts are the perfect fall food, calorie dense with fat and easily stored, providing body fat for calories through the winter and stored food when food is scarce.  Forest creatures such as turkeys, bears, and deer gorge themselves on these nuts until none can be found.  Other creatures such as squirrels, chipmunks, and Bluejays scurry around, both gorging themselves as well as storing huge numbers of seeds in tree cavities and underground.  These nuts are to be relocated when food is scarce and eaten.  Many, if not most, of these seeds will be relocated but many also will be lost, and thus a new crop of trees and a future forest is planted.
Hickory Nuts
Acorn and oak leaves.  The tan coloration of the small oak leaf above is caused by tannins oak leaves contain.

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