This article originally ran in The Wenatchee World in September 2019.
Every fall, I end up with a huge pile of oak leaves in my yard. Last October, my mom visited and we ended up piling up leaves in creative ways, creating ephemeral art that blew away with the next gust of wind.
It was a wonderful way to spend the afternoon with family. The next day, we gathered them all up and added them to my compost pile. It will become rich soil for my garden next year.
Fall leaves are one of those free toys nature gives kids and adults alike to play with. But they do more than just look pretty (and create more work for us adults). Here, we will learn a little bit about fall leaves, and how to explore them with your children.
Why do leaves change color and fall when the weather changes?
First, we have to look at the purpose of a leaf. A leaf exists to change sunlight, water and air into sugar to power the growth of the tree. This process is called photosynthesis. The key tool that leaves use for photosynthesis is chlorophyll, a molecule that is stored in the leaves and needles of trees, and sometimes in the bark.
Chlorophyll is green, and it’s what gives leaves their color. But leaves also contain other compounds such as carotenoids, which are bright reds and yellows. Most of the year, chlorophyll is at work converting light to sugars. A healthy leaf contains so much chlorophyll that it covers up the reds and yellows of the carotenoids. That means a leaf is actually red or orange or yellow all year long – we just can’t see it through the chlorophyll.
However, in the fall, the days get shorter, and the temperatures become colder. There is less light to convert, and colder temperatures make it harder for the chlorophyll to do its job. When chlorophyll no longer serves its purpose, it begins to break down, and the leaf drains the stored energy out of the leaf and deposits it in the roots. When it does, the bright fall colors show through.
This process is most noticeable in deciduous trees, which grow new leaves each year. But it also happens in the needles of evergreen trees. The only difference? The lifespan of an evergreen needle is more than one year. In Ponderosa pines, needles live for about 3-4 years. In the fall, you might notice Ponderosa pine trees looking a little scruffy, with plenty of brown needles. They shed these needles and grow new needles to replace them.
Here are some fun things you and your kids can do with fall leaves.
- Go for a fall leaf hike! Clara Lake is a great place to find one of two local species deciduous conifers, the Western Larch. You can also find beautiful displays of fall color on a trip to the Lake Wenatchee and White River areas. The Chatter Creek trail up the Icicle River Road contains an amazing density of vividly red vine maple within the first tenth of a mile. Or, follow the crowds up Carne Mountain for a display of alpine larches in early October.
- Create short-lived works of art with leaves, like I did with my mother.
- Use leaves as paintbrushes: find leaves with long stems and have your kids paint by holding the stem and dipping the broad end of the leaf in washable paint.
- Preserving leaves: slide your fall leaves in between two sheets of wax paper and cover with a cloth napkin. Press down on the leaf with a warm (but not hot) iron, sealing the leaves in the wax. Cut the leaves out – you can even leave enough paper on one side to cut a hole and hang your preserved leaves in your window.