Environmental Engineering Reference
In-Depth Information
so, only 4.6% of U.S. land is protected as wilderness—
almost three-fourths of it in Alaska. Only 1.8% of the
land area of the lower 48 states is protected, most of it
in the West. In other words, Americans have reserved
98% of the continental United States to be used as they
see fit and have protected only 2% as wilderness. Ac-
cording to a 1999 study by the World Conservation
Union, the United States ranks 42nd among nations in
terms of terrestrial area protected as wilderness, and
Canada is in 36th place.
In addition, only 4 of the 413 wilderness areas in
the lower 48 states are larger than 4,000 square kilome-
ters (1,500 square miles). Also, the system includes
only 81 of the country's 233 distinct ecosystems. Most
wilderness areas in the lower 48 states are threatened
habitat islands in a sea of development.
Almost 400,000 square kilometers (150,000 square
miles) in scattered blocks of public lands could qual-
ify for designation as wilderness—about 60% of it in
the national forests. For two decades, these areas have
been temporarily protected while they were evalu-
ated for wilderness protection. Wilderness supporters
would like to see all of them protected as part of the
wilderness system. This is unlikely because of the po-
litical strength of industries that see these areas as re-
sources for increased profits and short-term economic
growth.
Figure 8-27 lists some ways you can help sustain
the earth's terrestrial biodiversity.
8-8
ECOLOGICAL RESTORATION
Science: Rehabilitating and Restoring
Damaged Ecosystems
Scientists have developed a number of techniques for
rehabilitating and restoring degraded ecosystems and
creating artificial ecosystems.
Almost every natural place on the earth has been
affected or degraded to some degree by human activi-
ties. Much of the harm we have inflicted on nature is at
least partially reversible through
ecological restora-
tion:
the process of repairing damage caused by hu-
mans to the biodiversity and dynamics of natural
ecosystems. Examples include replanting forests,
restoring grasslands, restoring wetlands and stream
banks, reclaiming urban industrial areas (brown-
fields), reintroducing native species (p. 154), removing
invasive species, and freeing river flows by removing
dams.
Farmer and philosopher Wendell Berry says we
should try to answer three questions in deciding
whether and how to modify or rehabilitate natural
ecosystems.
First
, what is here?
Second
, what will na-
ture permit us to do here?
Third
, what will nature help
us do here? An important strategy is to mimic nature
and natural processes and ideally let nature do most
of the work, usually through secondary ecological
succession.
By studying how natural ecosystems recover, sci-
entists are learning how to speed up repair operations
using a variety of approaches. They include the fol-
lowing measures:
What Can You Do?
■
Restoration:
trying to return a particular degraded
habitat or ecosystem to a condition as similar as possi-
ble to its natural state. Unfortunately, lack of knowl-
edge about the previous composition of a degraded
area can make it impossible to restore an area to its
earlier state.
■
Rehabilitation:
attempts to turn a degraded ecosys-
tem back into a functional or useful ecosystem with-
out trying to restore it to its original condition.
■
Replacement:
replacing a degraded ecosystem with
another type of ecosystem. For example, a productive
pasture or tree farm may replace a degraded forest.
■
Creating artificial ecosystems:
for example, the cre-
ation of artificial wetlands.
Researchers have suggested four basic science-
based principles for carrying out ecological restoration.
Sustaining Terrestrial Biodiversity
• Plant trees and take care of them.
• Recycle paper and buy recycled paper products.
• Buy wood and wood products made from trees
that have been grown sustainably.
• Help rehabilitate or restore a degraded area of
forest or grassland near your home.
• When building a home, save all the trees and as
much natural vegetation and soil as possible.
• Landscape your yard with a diversity of plants
natural to the area instead of having a
monoculture lawn.
• Live in town because suburban sprawl reduces
biodiversity.
■
Mimic nature and natural processes and ideally let
nature do most of the work, usually through sec-
ondary ecological succession (Figure 8-28, p. 178).
■
Recreate important ecological niches that have
been lost.
Figure 8-27
Individuals matter:
ways to help sustain terres-
trial biodiversity.
Critical thinking: which two of these actions do
you believe are the most important? Which things in this list do
you plan to do?
