Environmental Problems, Their Causes, and Sustainability 1

Figure 12-10 Kudzu taking over a house and a truck. This vinecan grow 5 centimeters (2 inches) per hour and is now foundfrom east Texas to Florida and as far north as southeasternPennsylvania and Illinois. Kudzu was deliberately introducedinto the United States for erosion control, but it cannot bestopped by being dug up or burned. Grazing by goats and repeateddoses of herbicides can destroy it, but goats and herbicidesalso destroy other plants, and herbicides can contaminatewater supplies. Recently, scientists have found a commonfungus (Myrothecium verrucaria) that can kill kudzu within a fewhours, apparently without harming other plants.patches of forest, and anything else in its path (Figure12-10).This vine, sometimes called “the vine that ate theSouth,” has spread throughout much of the southernUnited States. It could spread as far north as the GreatLakes by 2040 if projected global warming occurs.Kudzu is considered a menace in the UnitedStates. But Asians use a powdered kudzu starch inbeverages, gourmet confections, and herbal remediesfor a range of diseases. A Japanese firm has built alarge kudzu farm and processing plant in Alabamaand ships the extracted starch to Japan.Although kudzu can engulf and kill trees, it couldeventually help save trees from loggers. Research atthe Georgia Institute of Technology indicates thatkudzu may be used as a source of tree-free paper.What Is the Role of AccidentallyIntroduced Species? Aliens TakingOverAgrowing number of accidentally introduced speciesare causing serious economic and ecological damage.Many unwanted nonnative invaders arrive from othercontinents as stowaways on aircraft, in the ballast waterof tankers and cargo ships, and as hitchhikers onimported products such as wooden packing crates.Cars and trucks can spread seeds of nonnative speciesimbedded in tire treads.In the late 1930s, the extremely aggressiveArgentina fire ant (Figure 12-9) was introduced accidentallyinto the United States in Mobile, Alabama. Theants may have arrived on shiploads of lumber or coffeeimported from South America or by hitching a ridein the soil-containing ballast water of cargo ships.These ants spawn and spread rapidly. Bother them,and up to 100,000 ants can swarm out of their nest to attackyou with their painful and burning stings.Without natural predators, fire ants have spreadrapidly by land and water (they can float) throughoutthe South, from Texas to Florida and as far north asTennessee and North Carolina (Figure 12-11). They arealso found in Puerto Rico and recently have invadedCalifornia and New Mexico.Wherever fire ants have gone, they have sharplyreduced or wiped out up to 90% of native ant populations.Their extremely painful stings have killeddeer fawns, birds, livestock, pets, and at least 80 peopleallergic to their venom. These ants have invadedcars and caused accidents by attacking drivers, damagedcrops (such as soybeans, corn, strawberries, andpotatoes), disrupted phone service and electricalpower, caused fires by chewing through undergroundcables, and cost the United States an estimated$600 million per year. Their large mounds,which raise large boils on the land, can ruin cropfields, and their painful stings can make backyardsuninhabitable.Widespread pesticide spraying in the 1950s and1960s temporarily reduced fire ant populations. Butthis chemical warfare hastened the advance of therapidly multiplying fire ant by reducing populationsof many native ant species. Worse, it promoted devel-19182000Figure 12-11Natural capitaldegradation:expansion of theArgentina fire ant insouthern states,1918–2000. Thisinvader is alsofound in PuertoRico, New Mexico,and California.(Data from U.S.Department ofAgriculture)236 CHAPTER 12 Sustaining Biodiversity: The Species Approach