Leaf Types

• This compound buckeye leaf consists of six leaflets that look like separate leaves.Hemera Technologies/AbleStock.com/Getty Images
  
  Deciduous trees have one of four different types of leaves. They can have simple leaves located opposite each other. A simple leaf has a single blade on a stalk. Maple trees are in this group. A second group of deciduous trees includes trees like willow and birch, which have simple leaves located alternately on a twig. Trees like ash belong in a third group of deciduous trees that have compound leaves located opposite each other. Compound leaves contain more than one leaf blade on a stalk. These blades are called leaflets and, to the untrained eye, they can look like separate leaves, but they are attached to a single stalk and make up a single leaf. The last group of deciduous trees includes trees like locust and walnuts, which have compound leaves located alternately on the twig.
  
  

Leaf Color

• Deciduous trees change color in the autumn when the leaves lose their chlorophyll.Jupiterimages/Photos.com/Getty Images
  
  Deciduous trees enter a dormant period during the winter, because there's not enough light or water for them to use for photosynthesis. In addition, if they didn't go dormant, the cold weather would damage the cells in their leaves. Rather than waiting for the leaves to be damaged, trees prepare for winter by breaking down the organic compounds found in the leaves' enzymes, and reabsorbing them to use for the next growing season. Chlorophyll is one of the first compounds deciduous trees start breaking down in the fall. Chlorophyll is what makes the leaves look green. As it's broken down, the leaves' orange, red and yellow colors start showing through.
  
  

Leaf Loss

• Deciduous trees lose their leaves in the fall.Jupiterimages/Photos.com/Getty Images
  
  In the fall, when nights grow longer, a layer of cells forms near the base of the leaf stem. This cell layer is known as the separation layer or abscission zone. The cells secrete enzymes that weaken the connection between the stem and the twig. Eventually, the cells separate and the leaf falls when wind or rain knocks it off the twig.
  
  

Forests

• Deciduous forests usually have a limited number of tree species.Jupiterimages/Photos.com/Getty Images
  
  Deciduous trees exist in temperate forests. These forests are found in the middle of Europe, the eastern half of North America, southwest Russia, Japan, eastern China and parts of South America including southern Chile and Paraguay. Because the soil in deciduous forests is very fertile, people have cleared many deciduous forests and turned them into farmland. In a temperate forest, the average temperature is 50 degrees Fahrenheit, and trees get about 30 to 60 inches of rain every year.