Environmental Engineering Reference
In-Depth Information
In the 1930s, the
kudzu vine
was imported from Japan
and planted in the southeastern United States in an at-
tempt to control soil erosion. It does control erosion.
Unfortunately, it is so prolific and difficult to kill that it
engulfs hillsides, gardens, trees, abandoned houses
and cars, stream banks, patches of forest, and anything
else in its path (Figure 9-12).
This plant, which is sometimes called “the vine
that ate the South,” has spread throughout much of the
southern United States. It could spread as far north as
the Great Lakes by 2040 if global warming occurs as
projected.
Although kudzu is considered a menace in the
United States, Asians use a powdered kudzu starch in
beverages, gourmet confections, and herbal remedies
for a range of diseases. A Japanese firm has built a
large kudzu farm and processing plant in Alabama
and ships the extracted starch to Japan.
Although kudzu can engulf and kill trees, it might
eventually help save trees from loggers. Researchers at
the Georgia Institute of Technology indicate that it
could be used as a source of tree-free paper.
Figure 9-12
Natural capital degradation:
kudzu taking over an aban-
doned house in Mississippi. This vine can grow 5 centimeters (2 inches)
per hour and is now found from east Texas to Florida and as far north
as southeastern Pennsylvania and Illinois. Kudzu was deliberately
introduced into the United States for erosion control, but it cannot be
stopped by being dug up or burned. Grazing by goats and repeated
doses of herbicides can destroy it, but goats and herbicides also de-
stroy other plants, and herbicides can contaminate water supplies. Re-
cently, scientists have found a common fungus that can kill kudzu within
a few hours, apparently without harming other plants. Stay tuned.
Science: Accidentally Introduced Species
Agrowing number of accidentally introduced
species are causing serious economic and ecological
damage.
Many unwanted nonnative invaders arrive from other
continents as stowaways on aircraft, in the ballast wa-
ter of tankers and cargo ships, and as hitchhikers on
imported products such as wooden packing crates.
Cars and trucks can spread seeds of nonnative species
embedded in tire treads.
In the late 1930s, the extremely aggressive Ar-
gentina fire ant (Figure 9-11) was introduced acciden-
tally into the United States in Mobile, Alabama. The
ants may have arrived on shiploads of lumber or cof-
fee imported from South America or by hitching a ride
in soil found in cargo ships' ballast water.
Without natural predators, fire ants have spread
rapidly by land and water (they can float) throughout
the South, from Texas to Florida and as far north as
Tennessee and Virginia (Figure 9-13). They are also
found in Puerto Rico and recently have invaded
California and New Mexico.
Wherever fire ants have gone, they have sharply
reduced or wiped out as much as 90% of native ant
populations. Bother them, and 100,000 ants may
swarm out of their nest to attack you with painful and
burning stings. They have killed deer fawns, birds,
livestock, pets, and at least 80 people who were allergic
to their venom. They have invaded cars and caused ac-
cidents by attacking drivers, damaged crops, disrupted
phone service and electrical power, caused fires by
chewing through underground cables, and cost the
United States an estimated $600 million per year. Their
introduced into the United States, have caused eco-
logical and economic harm. According to biologist
Thomas Lovejoy, harmful invader species cost the U.S.
public more than $137 billion each year—an average of
$16 million per hour!
Nonnative species threaten almost half of the
more than 1,260 endangered and threatened species in
the United States and 95% of those in Hawaii, accord-
ing to the U.S. Fish and Wildlife Service. They are also
blamed for two-thirds of the fish extinctions that oc-
curred in the United States between 1900 and 2000.
An example of a deliberately introduced plant
species is the
kudzu
(“CUD-zoo”)
vine,
which grows
rampant in the southeastern United States (see follow-
ing Case Study). Deliberately introduced animal spe-
cies have also caused ecological and economic damage.
Consider the estimated 1 million
European wild (feral)
boars
(Figure 9-11) found in parts of Florida and other
states. They compete for food with endangered ani-
mals, root up farm fields, and cause traffic accidents.
Game and wildlife officials have failed to control their
numbers through hunting and trapping and say there
is no way to stop them. Another example is the esti-
mated 30 million
feral cats
and 41 million
outdoor pet cats
introduced into the United States; they kill about 568
million birds per year!
Science Case Study: Deliberate Introduction
of the Kudzu Vine
The nonnative kudzu vine has spread throughout
much of the southern United States and is almost
impossible to control.
