Fall always seems to sneak up on us. Summer weather still prevails on the first day of autumn and then suddenly and without warning the heat and humidity of summer are replaced with drier days and cooler nights.
Here and there, one glimpses autumn colors peeking out of the green landscape. Then just as we're beginning to enjoy the colorful landscape, those warm hues are replaced by dismal browns as leaves carpet lawns and gardens.
Actually, this leaf-shedding process, known as abscission, has been occurring for several weeks. Cells, located at the spot where the leaf stem is attached to the tree, toughen and begin to form a protective, waterproof scar. The cells in the leaf stem itself swell, weaken and degenerate. This interferes with the flow of moisture and nutrients into the leaf, reducing the production of a pigment, known as chlorophyll, which gives leaves their green color.
The leaf is the food factory for the tree. Chlorophyll in a leaf uses the sun's energy to convert carbon dioxide and water into sugar-food for the tree. As the days shorten, there is less sunlight energy to manufacture food. Nutrients and minerals are withdrawn from leaves and transported to the permanent parts of trees such as the trunk, stems and roots.
As the chlorophyll breaks down, the other pigments in the leaves-which were masked by the chlorophyll-are revealed, giving trees their fiery fall colors.
The final step in the abscission process occurs when a tree sheds its leaves. Gradually, the bond between leaves and a tree weakens. The tiny veins that carried sap to the leaves all summer long are sealed off. Leaves fall to the ground, encouraged by wind or by the sheer weight of gravity. Now the dominant color is brown as the chemical reaction of decomposition starts.
If you, like me, detest the idea of raking and bagging leaves just to have them dumped in a landfill, there is an alternative.
These dry, brown leaves may not be beautiful, but they are valuable. Instead of bagging leaves, try composting them. It's the most ecological and economical (and least labor intensive) way to dispose of leaves. Composting is the decomposition of organic materials, such as leaves, grass and food scraps, by microorganisms. The result is a recycled, earthy-smelling, soil-like material. It's a way to get rid of yard waste. It's also easier and cheaper than bagging wastes for the landfill and saves landfill space.
Mulched leaves can be left on lawns. As the leaves decompose, they release nutrients back into the soil, reducing the need to fertilize a yard next spring.
Not only do leaves add nutrients to to lawns, gardens and landscape plants, but composting helps to retain water in sandy soil and breaks up heavy clay soils.
Using this rich natural fertilizer means less dependence on chemical fertilizers. Many people tend to overapply fertilizers, thinking that more fertilizer means a greener lawn. But the excess nutrients that are not taken up become major pollutants in local waterways and the Chesapeake Bay. Composting leaves helps to reduces one's dependence on fertilizers.
Leaves also form an insulating barrier around plants, reducing moisture loss and damage from severe winter weather. This also reduces the amount of nutrients that runoff the land into streams and rivers and, ultimately, the Chesapeake Bay.
To learn more, contact your state Cooperative Extension Office:
- Pennsylvania Cooperative Extension, Pennsylvania State University: 814-863-7640 or http://composting.cas.psu.edu/
- Maryland,Cooperative Extension, Home and Garden Information Center, University of Maryland: 800-342-2507 or www.hgic.umd.edu/index.cfm;
- Virginia Cooperative Extension, Virginia Tech at 540- 231-5299 or www.ext.vt.edu/index.php.
- District of Columbia / District Department of the Environment: 202-535-2600 or http://green.dc.gov/green/site/default.asp