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To find out why these areas do not have forest, you will
need to look at a map of land uses and
land covers in the Cape Fear
River Basin. Both forest maps and land use and land cover maps
are made using pictures taken from the air. These pictures can be
taken from airplanes or by satellites. The land use and land cover map you will look at
was made from a picture taken by a satellite.
Using Satellites to Make Maps
When the sun’s
light hits the surface of the Earth, some of the light bounces off and is
reflected
back into space. The type of light that is reflected depends on what
type and how many plants are growing in an area. The light reflected
by a forest is different from the light reflected by a grassland.
These are both different than the light reflected by a city street.
When light travels it moves like a wave. Different colors of light have different
sizes of waves, called
wavelengths. The wavelengths that are reflected when light hits
an object give that object its color. Not all of the wavelengths that
are reflected can be seen by the
human eye. Some are invisible. Satellites can record all of the
wavelengths of light that are reflected by the Earth’s surface, even
those that are invisible.
The
wavelengths of light that are reflected by a land use or
land cover are called its unique "signature". Scientists use these signatures to
map
different ecosystems from the satellite images.
The map to the left
shows land use and land cover in the Cape Fear River Basin.
It shows both natural areas
(land cover) and human uses such as cities and farming (land
use).
There are four land cover classes on the map: "forest",
"wetlands", "water", and "bare land" (sand dunes or cleared land). There are also
two human land use classes:
"cities and towns" and "farms".
Click on the map to continue your journey...
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