School of Life Sciences | Ask A Biologist

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Anatomy of the Temperate Forest

show/hide words to know

  • Climax: the top or final state of something, like an ecosystem.
  • Pioneer: the first to move into an area. In plants, pioneers are usually very fast growing and can't survive in shade.
  • Tolerate: to allow or endure something or someone that is unfavorable. In medical terms, it is a person's ability to take a drug or treatment without serious side effects or discomfort.

Forest in FranceIt’s all about the trees. Trees are the most important members of the temperate forest community. They provide the structure and create the environment for everything beneath them. The forest can be thought of in “layers” with the treetops being the top layer, called the canopy. Small plants grow in the understory, on the bottom right above the forest floor.

Stunted by Shade

There can also be subcanopy or intermediate layers, where young trees grow; these will be giants some day when they reach the canopy.  The shade that the canopy makes can make it hard for some plants to survive in the forest, because they can’t get enough light to grow. While a tree may produce thousands of seeds in a given year to blanket the forest floor with seedlings, less than one out of every 100 of these seedlings will survive.  It’s a harsh life for a little seedling.

Forest succession

Different species of trees need different levels of light. There are some species, like sugar maple (named for the delicious maple syrup we get from it) which can tolerate shade for decades. These seedlings can live in the shade and grow incredibly slowly (a waist-high tree can be more than 30 years old!) as they wait for a tree to fall over so light reaches the forest floor. On the other hand, fast-growing trees can’t survive the shade. 

Changing Seasons

Maple leaf changing colorFall brings beautiful colors of all different shades to the deciduous forests. Some maples turn orange, oak leaves show dark reds, and hickories become bright yellow. These colors are clues that the trees are shutting down for the winter.

Chlorophyll enables trees to capture energy from light for photosynthesis. In fall, they break down chlorophyll and other photosynthetic chemicals in their leaves. The colors we see have actually been there all summer, but their presence is masked by the green chlorophyll. Only when it’s removed can we see the colors of the other compounds and pigments in leaves. 
 
One reason trees do this is to survive the cold winter temperatures. If they kept their leaves, it’s possible a heavy snow could pile up on their branches and break them off. It’s safer to stay dormant in winter, using stored sugars from the summer, then to risk heavy damage from snow. Plus, because winters are colder, days are shorter, and the sun is lower in the sky, less photosynthesis and growth are possible anyway.

Peeking Underneath

Decaying plant leaves

But the trees and understory aren't where all the action happens in a temperate forest. There’s a lot more to soil than just dirt. If you go out to the forest and pick up a pinch of soil, how many species do you think you’d be holding? There’s a good chance there are more than 50,000 species between your fingertips! 

Very diverse communities of microbes, including bacteria and fungi, populate temperate forest soils, consuming and decomposing the plant litter and animal remains that fall there.
 
These microbes go dormant in the winter too, just like the trees. This allows nutrients and dead plant litter to build up in the soil so that it can be rich enough to support lots of plant growth. When spring comes, they start decomposing again. 

Images via Wikimedia Commons. Seedlings image by FLamiot.

Forest understory

In temperate forests, young tree seedlings often blanket the forest floor.

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Forest understory

In temperate forests, young tree seedlings often blanket the forest floor.

Share to Google Classroom

Be part of Ask A Biologist

by volunteering, or simply sending us feedback on the site. Scientists, teachers, writers, illustrators, and translators are all important to the program. If you are interested in helping with the website we have a Volunteer page to get the process started.