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Carpenter Costin's Blog

Why Do Leaves Turn Color in Fall?

Posted by Carpenter Costin

Oct 14, 2016 10:05:32 AM

Autumn in the Northeast can be a spectacular season of bright blue skies, cool temperatures, and brilliant leaf color.

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Tree and plant leaves contain pigments that give them their color. Three pigments are involved in fall color:

  • Chlorophyll — gives leaves their green color
  • Carotenoids — provide the yellow, orange, and brown colors
  • Anthocyanins — give the red and purple colors. In contrast to the other two pigments, anthocyanins are produced in the autumn, in response to bright light and excess plant sugars in the leaf cells

During the growing season, most tree leaves are green because they are full of chlorophyll. Plants use chlorophyll to capture sunlight for photosynthesis, the process that enables them to manufacture their own food. The amount of chlorophyll is so high during the summer that the green color masks all other pigments present in the leaf. As the days grow shorter in the fall, chlorophyll production slows down and eventually stops. The carotenoids and anthocyanins that are present in the leaf then become visible.

Do Different Kinds of Trees Turn Different Colors?
Certain colors of leaves are characteristic of particular species of trees.

  • Oaks turn red, brown, or russet;
  • Hickories turn golden bronze;
  • Dogwood turns purplish red;
  • Beech turns light tan;
  • Red Maple turns brilliant scarlet;
  • Sugar Maple turns orange-red;
  • Black Maple turns glowing yellow;
  • Sourwood turn crimson;
  • Birches turn golden yellow.

Why Do Leaves Fall?
Deciduous trees drop their leaves in order to survive the harsh conditions of winter. Stems, twigs, and buds are equipped to survive extreme cold. Tender leaf tissues however, would freeze in winter, so plants must either protect their leaves or shed them.

Fallen leaves are not wasted, they decompose and restock the soil with nutrients. The rich layer of decomposing leaves protects the roots of other plants on the forest floor and absorbs and holds rainfall. Imitating nature by mulching with shredded leaves provides similar benefits for trees and shrubs in the home landscape.

**Excerpts from US Dept of Agriculture, Northeastern Area Fact Sheet SP-01-01

Topics: Fall Landscape Care