Tree Canopy Name: Kyle Status: Student Grade: 6=8 Location: CA Country: United States Date: November 2006 Question: What is the difference between tree density and tree cover? Replies: Kyle, Tree cover and tree density are different. You can have trees with a large expanse of leaves at the top of the trees, giving a large cover, but small density, such as a forest of honey locust trees. On the other hand you can have both a large tree density and cover, such as you find in some coniferous forests (fir, pine, etc.). Dense tree forests allow little light to reach the ground, whereas some forests with a lot of cover can still allow quite a bit of light to reach the surface (the light shines in under the individual tree canopies). We use a measurement called Leaf Area Index (LAI for short) to determine canopy density (whether for trees, crops, grass, etc.). The canopy includes the entire tree (or grass, crops, etc.). The measurement compares the amount of sunlight above the canopy with the amount near the surface. The larger the LAI, the denser the canopy is. An LAI of 1 indicates that, effectively, the leaves of the plants cover the same area as the ground. An LAI of more than 1 indicates that there are multiple leaf layers that each contribute to depleting the amount of light under the canopy. As the growing season progresses through the Spring and Summer, the LAI increases as plant's and deciduous tree's leaves grow and fill out. LAI is therefore a good measure of the mass and density of leaves. David R. Cook Meteorologist Climate Research Section Environmental Science Division Argonne National Laboratory Click here to return to the Environmental and Earth Science Archives

NEWTON is an electronic community for Science, Math, and Computer Science K-12 Educators, sponsored and operated by Argonne National Laboratory's Educational Programs, Andrew Skipor, Ph.D., Head of Educational Programs.

For assistance with NEWTON contact a System Operator (help@newton.dep.anl.gov), or at Argonne's Educational Programs