By Kristen Swanberg, Senior Director of Education
Illustrations by Mary Lamb Greene
Each fall a transformation takes place across our state in forests, in parks, and even in your own backyard. Trees turn from green to yellow, orange, red, and even purple – all in just a few weeks. Why does this happen? And more importantly, how does it happen?
Just as we pull out our winter coats and wooly mittens, trees also need to get ready for the freezing winter temperatures. As the fall air gets cooler and there is less daylight, trees begin to shut down their systems for winter. They do this by moving nutrients out of the leaves and into their branches, trunk, and roots.
Green leaves contain yellow and orange colors in the spring and summer. You just can’t see them because they are covered up by green chlorophyll (chlo-ro-phyll). Chlorophyll uses the sun’s energy to make sugars that feed the tree in the warmer months. As sunlight hours decrease and the tree’s internal system begins to slow down, the leaves are sealed off from the tree’s moisture and nutrients. This causes the green chlorophyll to disappear, allowing the yellows, reds, oranges, scarlets, and purples to come alive!
Did you know the weather plays a big role in how colorful the fall will be? If we have bright, cool fall days with chilly but not freezing nights, there will be brilliant leaf colors.Â The yellow, orange, and brown colors are called carotenoids (ca-rot-en-oid).Â Red and purple colors are called anthosyanins (an-tho-cy-a-nin). Different tree species will show off specific colors in the autumn.
Fun Fall Activities…
Leaf Rubbings. Place a leaf vein-side-up on a table. Position a piece of paper over the leaf and secure the edges of the paper with tape. Using the side of a crayon, color over the surface of the paper. A leaf impression magically appears!
Go on a leaf scavenger hunt!
Search for different leaf shapes and colors then try to identify what kind of tree they came from. Avoid poison ivy — if you find “leaves of three, let them be!” A good reference for kids is the Peterson First Guide to Trees.
Situated on a 28-acre wildlife refuge in Bristol, Rhode Island, Audubon’s Environmental Education Center is open year-round providing walking trails, nature programs, and exhibits for the whole family to discover.Â For more information and a complete calendar of events, visit www.asri.org or call (401) 245-7500.