What Is Biodiversity?
There are many different organisms and many different habitats in which
organisms live. Most of these ecosystems have taken hundreds or thousands
of years to develop. The fact that there are so many varieties of life
and ecosystems means there is biodiversity on the earth (bio means "life"
and diversity means "differences").
Out of all the species of life that have lived on the earth, scientists
believe that most have become extinct. It is also believed that much
of this extinction occurred during five periods in the earth's history.
While no one knows exactly what happened during these periods to cause
these mass extinctions, it was likely a combination of environmental
factors.
Today, as humans alter ecosystems, scientists are looking into the
effects of habitat changes on biodiversity. Changes range from loss
of forest cover, to over harvesting of certain species, to accidental
(or intentional) introduction of non-native organisms. In some cases,
as ecosystems change and certain species are lost through extinction,
it may begin a chain of events that leads to extinction of several other
organisms. Extinctions lead to a loss of biodiversity, something that
cannot be recovered in thousands of years.
As the human population grows, it is necessary for people to be aware
of the need for biodiversity, and to include this idea in planning for
the future. While we know that extinction is a natural occurrence, we
must think about how our actions will affect this process.
Biodiversity in the School Yard
Assign students to groups of two. Provide each group with a piece of
string and a data collection sheet. Make sure all strings are the same
length. Have each group of students proceed to a different area of the
school yard. Have the students lie the string on the ground in a straight
line. Record all living organisms that can be found under the line.
This will include ants, worms, grass, and weeds. Remind the students
about the things they cannot see, such as bacteria, fungi, and other
microscopic plants and animals. Record the total number of species found
at each location. Encourage students to discuss what differences were
found and possible explanations for the differences.
Discuss these additional questions:
- Elk were once found in Illinois. They require large areas of land
to forage for food. Why aren't there Elk in Illinois now? (Most of
their original habitat is now cropland.)
- What actions can be taken to improve habitat for wildlife
(a. in the wildlife, and b. in the country - think about
their needs for food, water, and shelter).
- Who are the people in your area that help manage wildlife populations?
