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Frog Zoning
Vernal pools can be destroyed as amphibian habitat if too much of
the land around them is turned over to human use.
Wildlife Conservation
Society scientist Dr. Michael Klemens has produced a system by which
town planners and developers can gauge the area around a vernal pool
that must be left undisturbed.
Under this system, any vernal pool that
is expected to provide amphibian breeding habitat needs 100 feet of
undisturbed land around its edges. This is known as the "vernal
pool envelope."
Beyond the envelope, critical habitat areas can differ for different
species. But as a rule, Dr. Klemens recommends that no more than 25%
of the critical habitat areas around vernal pools be developed. The
following graphic shows the varying sizes of critical habitat for
four amphibian species.
| © WCS Metropolitan Conservation Alliance. |
Now put yourself in the shoes of a watershed manager. Look at the
two aerial photos below and answer the following questions about the
vernal pool envelopes in each one. The large circle represents the
critical habitat for an amphibian species.
© WCS Metropolitan Conservation Alliance.
Orthophotography courtesy of Rhode Island Geographic Information
System. |
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1. How much of the vernal pool envelope (red circle)
is intact in figures A and B?
2. How much critical habitat area(orange circle) is left
in A and B?
3. Which photo-A or B-would you recommend for housing
development. Explain your reasons in one or two paragraphs. |
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© 2004 Wildlife Conservation Society.
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