quartz crystals have been minedinBrazil, and smaller crystals are found in the United States—for example, in Arkansas and New York State (the “Herkimer dia- mond” deposits). However, Arkansas’ mining of lascas—nonelectronic-grade quartz that is used largely asfeedstock toculture (synthesize)high-grade quartz crystals for use in electronic and other applica- tions—ended in 1997, and cultured quartz crystals are now produced primarily in Asia. Primary Uses Cultured quartz crystals are used mainly in electron- ics. Lumbered (natural) quartz crystals cost twice as much per kilogram. The United States has about 7,000 kilograms of natural quartz stockpiles; the larger of these canbe usedto seed theculturing process. Sec- ondary uses are found in the gemstone industry. Technical Definition Quartz is sparingly soluble in water (6 parts per mil- lion) and exists in solution as silicic acid (formula H 4 SiO 4 ). Animals and plants take up the silicic acid, which can be incorporated in tissues. Description, Distribution, and Forms A striking example of quartz is the gradual petrifica- tion of trees, which occursas the silica redeposits in the wood. Grasses such as bullrushes have considerable sil- ica contentand were chewed as primitivetoothbrushes by earlysettlers in theUnited States. Cattle feeding on grass can develop silica deposits in the urinary tract that may be life-threatening. Amorphous silica is also found in sponges, sea cucum- bers, rice hulls, bamboo, and palm fronds. Diatoms build their exoskeletons of silica, and after their death an adsorbent mineral called diatomaceous earth (kieselguhr) re- mains. Crystalline quartz occurs rarely in the biosphere, but quartz crystals (100 nano- meters in size) have been found in the or- ganism Chlorochytridion tuberculatum. Solid quartz is not particularly toxic when swallowed, and the silica content of foods is easily tolerated, but quartz dust arising from mining activities is recognized as an inhalation hazard, the smallest parti- cles (less than 5 microns) of which are the most harmful. Inhaled dustcauses scarring and fibrosis in the lungs (silicosis), with gradual loss of function. The effects are worse in cigarette smokers. The lung lesions caused by silicosis can develop into cancer. Silicon is an essential nutrient in a variety of spe- cies, including chickens, beets, and presumably hu- mans. Silicon’s precise function is not known, but it appears to be involved in regulating the uptake of iron and aluminum. Until relatively recently, analyti- cal methods involving silicon depended on wet chem- ical methods, which tended to give high results, so early claims of silicon should essentiality be treated with skepticism. History Quartz has been known since prehistoric times, when flint arrowheads and spear tips were used in hunting and fighting. The alchemist and metallurgist Georgius Agricola used the term quartzum in his sixteenth cen- tury writings in which he latinized a central European term kwardy, meaning hard. In 1813, Jean-Baptiste Biot reported the existence of left- and right-handed (chiral) quartz crystals, while, in 1880, Pierre Curie and his brother Jacques Curie described quartz’s pi- ezoelectric property. Quartz crystals became impor- tant in radio equipment in World War II, leading to a shortage of suitable natural material and to the devel- opment of the hydrothermal process for manufactur- ing cultured crystals. Obtaining Quartz Quartz sand is abundant at the surface of the Earth and is easily collected by surface mining techniques. 988 • Quartz Global Resources Quartz crystals are used in electronics. (United States Department of Agri- culture) Large perfect crystals are rarer; they may occur un - derground or embedded in rock. Brazilian quartz is valued for the size and perfection of its crystals, which are mined without the use of explosives and are hand-sorted and graded. Since the 1950’s producing cultured quartz crystals has become possible, which satisfy most of the demand of the modern electron- ics industry. In the hydrothermal method of crystal growth, the lasca (purified silica) dissolves in an alka- line solution at elevated temperature, and layers of quartz are grown on a seed crystal in a cooler section of theapparatus. Inthe past,quartz crystal was consid- ered so vital for military uses that a U.S. national de- fense stockpile of more than 600,000 kilograms was amassed. Toward the end of the twentieth century most of this stockpile was sold off. Uses of Quartz Cultured quartz finds its major use in the electronics industry, where its piezoelectric property is exploited in oscillators for controlling circuits (for example, in radio receivers). Quartz crystals are used in a wide va- riety of consumer electronics, from computers to cel- lular telephones. Quartz also has optical uses in ultraviolet lamps and laser optical systems. Vitreous quartz is a chemi- cally resistant high-temperature material used for lab- oratory ware (combustion tubes, crucibles, and so on). Silica, either amorphous or as quartz, occurs widely, notonly in sand and rock butalso in formsthat are valuedas gems.Amethyst (purple), citrine (yellow or brown), and rose quartz are semiprecious forms. Other minerals consisting largely of quartz are jasper, onyx, flint, chalcedony, and agate. Quartz sand is made into vast quantities of glass and cement, and it serves as the source of silicon car- bide, elemental silicon, and all sorts of synthetic sili- cates and silicones. The piezoelectric effect in quartz is exploited in crystal oscillators: An oriented quartz crystal in the form of a thin slice is clamped between electrodes and subjected to an electric field. The re- sulting resonant vibration of the crystal can be used as a frequency standard in radio receivers and as a time standard in watches and clocks. John R. Phillips Further Reading Hall, Cally. Gemstones. 2d American ed. Photography by Harry Taylor. New York: Dorling Kindersley, 2002. Iler, Ralph K. The Chemistry of Silica: Solubility, Polymer- ization, Colloid and Surface Properties, and Biochemis- try. New York: Wiley, 1979. Kogel, Jessica Elzea, et al., eds. “High Pure and Ultra- High Pure Quartz.” InIndustrial Minerals and Rocks: Commodities, Markets, and Uses. 7th ed. Littleton, Colo.: Society for Mining, Metallurgy, and Explora- tion, 2006. O’Donaghue, Michael. Gems: Their Sources, Descrip- tions, and Identification. 6th ed. Oxford, England: Butterworth-Heinemann, 2006. _______. Quartz. Boston: Butterworths, 1987. Pellant, Chris. Rocks and Minerals. 2d American ed. New York: Dorling Kindersley, 2002. Schumann, Walter. Gemstones of the World. 3d rev. and expanded ed. New York: Sterling, 2007. Sofianides, Anna S., and George E. Harlow. Gems and Crystals from the American Museum of Natural History. Photographs by Erica Van Pelt and Harold Van Pelt. New York: Simon and Schuster, 1990. Web Sites Natural Resources Canada Canadian Minerals Yearbook, Mineral and Metal Commodity Reviews http://www.nrcan-rncan.gc.ca/mms-smm/busi- indu/cmy-amc/com-eng.htm U.S. Geological Survey Quartz http://minerals.er.usgs.gov/minerals/pubs/ commodity/gemstones/sp14-95/quartz.html U.S. Geological Survey Silica: Statistics and Information http://minerals.usgs.gov/minerals/pubs/ commodity/silica/index.html#myb See also: Abrasives; Brazil; Ceramics; Diatomite; Gems; Granite; Minerals, structure andphysical prop- erties of;Mohs hardnessscale; Orthosilicate minerals; Pumice; Sand and gravel; Silicates; Silicon. Global Resources Quartz • 989 R Radium Category: Mineral and other nonliving resources Where Found The element radium is found only in uranium-bearing ores. The most concentrated deposits of uranium are uraninite (pitchblende) and carnotite. The first de- posits of pitchblendemined were inthe Czech Repub- lic, but later extensive deposits were found in the Democratic Republic of the Congo and in Canada’s Great Bear region. Carnotite is found in the sand- stone of the western United States. The most signifi- cant U.S. source is in Utah. Oceans and other surface waters have concentrations of about 10 −14 grams of radium per liter of water. Primary Uses Radium has few practical uses but has historical im- portance. Radium is used to treat some cancers. It is also used in metallurgy andother industrialand scien- tific applications,and it has a rolein theproduction of environmental radiation. Technical Definition Radium (symbol Ra) is a radioactive metallic element with atomic number 88 and atomic weight 226.025. Located inGroup IIAof theperiodic table,it ischemi- cally similar to barium. Radium has twenty-five isoto- pic forms (mass numbers 206-230), all unstable. Pure radium is brilliant white, but it blackens as it rapidly oxidizes in air. Pure radium and its salts are lumines- cent. Radium has a melting point of 700° Celsius, a boiling point of 1,737° Celsius, and density of 5.5 grams per cubic centimeter. Description, Distribution, and Forms Naturally occurring radium is predominantly the iso- tope radium 226. With a half-life of 1,620 years, it re- sults from radioactive disintegration of uranium (U 238 ). Because of its long half-life (4.5 billion years), U 238 serves as an effectively constant source of Ra 226 . The radium and uranium are in equilibrium with each other in an undisturbed sample of ore, with a fixed ratio of 1:3,000,000. Radium is an environmental concern as an intense source of alpha and gamma radiation, and its radioac- tive daughter, radon, is extremely dangerous at high levels. Radon is present in nearly all rock, is a compo- nent of air, and is ordinarily of little concern. How- ever, when highly concentrated it is dangerous be- cause of its alpha radioactivity and because it decays successively to the particulate daughters polonium (Po 218 ) and bismuth (Bi 214 ). These radioactive iso- topes have short half-lives, and when deposited in the lung their subsequent decay increases the risk of lung cancer. Thus, where uranium is found, radium is found, and in turn radon and its decay products. More than 50 percent of the U.S. population’s ordi- nary exposure to radiation is through radon. Conventional uranium mining leaves nearly all the radium in the tailings and the water used during extraction. An alternative uranium mining technique involves pumping chemical solutions into the ground to wash out uranium salts. In drilling for petroleum ex- ploration and recovery, uranium- and radium-bearing formations are often disturbed. These are only some of the sources of radioactivity that are potentially dan- gerous unless properly treated and discarded. History In 1898, Marie Curie foundthat only thosesubstances containing uranium or thorium emitted the penetrat- ing radiation found earlier by Antoine-Henri Bec- querel. Curie then found that the uranium-bearing mineral pitchblende exhibited far more intense emis- sions than could be accounted for by the amount of uranium present. Marie and Pierre Curie were able to isolate a new radioactive element,polonium, byprecip- itation with bismuth. Further analysis of a much larger sample of pitchblende led them to use precipitation with barium to isolate an even more intense, rarer source of radiation—radium.The total world produc- tion of radiumfrom 1898 to1928 wasonly500 grams. The discovery of radium led directly to the theory of radioactivity. Radium was the principal high-inten- sity radioactive source used to study atomic and nu - clear structure. It has since been supplanted by other radioisotopes that are safer and less costly. Obtaining Radium Radium is always found with uranium. The two pri- mary uranium ores are pitchblende and carnotite. Pitchblende is a specific variety of uraninite, a form of uranium oxide. Pitchblende is dark and lustrous in appearance, and it is found principally in hydrother- mal veins.Carnotiteis a hydrous vanadate (vanadium- oxygen compound) of potassium and uranium, usu- ally found in sandstone or other sedimentary rock in the form of a loose aggregate or powder. The char- acteristic yellow color of carnotite, even in small amounts, stains sandstone. Carnotite is also the main source of the element vanadium. Other uranium- bearing ores are autunite, torbernite (chalcolite), and tyuyamunite. Extraction of radium from these ores is very diffi- cult. A barium compound is added to the ore to act as a carrier for the radium, since barium and radium are chemically similar. The barium and radium sulfates are removed from the remainderof theoreby precipi- tation. The sulfates are converted into sulfides or car- bonates, which dissolve in hydrochloric acid. The bar- ium chloride is then separated from the radium chloride by successive fractional crystallizations. The pure metallic form is usually not isolated, since ra- dium is more easily handled and used in chloride or bromide form,and itsradioactive properties are unaf- fected by combination with other elements. Uses of Radium In the early twentieth century, radium was used for treatment of many types of cancer, the gamma ra- diation from radium’s daughter isotopes being the operative agent. It has been largely, though not com- pletely, superseded by less costly, more powerful iso- topes (particularly cobalt 60 and cesium 137) and accelerators. Zinc sulfide in combination with a radium salt forms a luminescent material. Such luminous paints were used to mark watch and meter dials, although radium has now been replaced by less hazardous promethium. Many young women employed in dial painting licked the tips of their brushes to produce a fine point, thus ingesting radium. In addition, water containing radium was often prescribed as a general tonic in the early part of the century. As a result of these practices many people developed anemia, leu- kemia, or bone cancer. Radium, chemically similar to calcium, makes its way to the bone and is bound there. Decay of the radium or its daughter isotopes causes destruction of the bone marrow, and/or bone cancer. Radium is used in metallurgy for radiographic test- ing of metal castings and welds. Similarly, radium is used for well-logging in prospecting for petroleum. Radium combined with beryllium produces a moder- ately intense source of neutrons. Michael K. Rulison Further Reading Greenwood, N. N.,and A.Earnshaw.“Beryllium, Mag- nesium, Calcium, Strontium, Barium, and Ra- dium.” In Chemistry of the Elements. 2d ed. Boston: Butterworth-Heinemann, 1997. Harvie, David I. Deadly Sunshine: The History and Fatal Legacy of Radium. Stroud, England: Tempus, 2005. Hayter, Charles. An Element of Hope: Radium and the Re- sponse to Cancer in Canada, 1900-1940. Montreal: McGill-Queen’s University Press, 2005. Henderson, William. “The Group 2 Elements: Beryl- lium, Magnesium, Calcium, Strontium, Barium, and Radium.”In Main Group Chemistry. Cambridge, England: Royal Society of Chemistry, 2000. Landa, Edward.Buried Treasure to BuriedWaste: TheRise and Fall of the Radium Industry. Golden: Colorado School of Mines Press, 1988. Mould, Richard F. A Century of X-Rays and Radioactivity in Medicine: With Emphasis on Photographic Records of the Early Years. Philadelphia: Institute of Physics, 1993. Pflaum, Rosalynd. Grand Obsession: Madame Curie and Her World. New York: Doubleday, 1989. Segré, Emilio. From X-Rays to Quarks: Modern Physicists and TheirDiscoveries. SanFrancisco: W.H. Freeman, 1980. Selman, Joseph.The Fundamentalsof X-Rayand Radium Physics. 8th ed.Springfield, Ill.:C.C. Thomas,1994. Web Sites U.S. Geological Survey Resources on Isotopes http://wwwrcamnl.wr.usgs.gov/isoig/period/ ra_iig.html Web Elements Radium: The Essentials http://www.webelements.com/radium See also: Isotopes, radioactive; Nuclear energy; Nu - clear waste and its disposal; Radon; Uranium. Global Resources Radium • 991 Rain forests Categories: Ecological resources; plant and animal resources Rain forests are complicated tropical ecosystems with extremely high levels of biodiversity. Occupying less than 6 percent of the Earth’s surface, they contain at least 50 percent of the world’s known plant and ani- mal species and produce at least 20 percent of Earth’s oxygen. The rain forests are being destroyed at such an unprecedented rate, however, that if the trend contin- ues, no sustainable tropical rain forests will remain by the middle of the twenty-first century. Background Tropicalrain forests are the most complex ecosystems on Earth, consisting of interacting systems of vegeta- tion and animal species so interdependent that dis- tressing one part can cause unpredictable and often irreversible damage. Temperatures typically range from 20°Celsius to 34°Celsius with annualrainfall be- tween 127and 660centimeters andhumidity between 77 and 88 percent. Seventypercent of theplants inthe rain forest are trees, with more types thanin any other region of the world. Each region is individually diver- sified; species found in one area may differ radically fromthose inanother section severalkilometers away. The rain forests surrounding the Amazon basin in South America represent the last great contiguous ex- panse of tropical rain forest remaining in the world. Containing at least 20 percent of the Earth’s higher plant species and an equal percentage of the world’s birds, Amazonia is being systematically devastated by human actions. About 20 percent has already been destroyed, and the rate has accelerated; in the mid- 1990’s, about 5,600 hectares were being cleared every day. The environmental, economic, and social conse- quences of large-scale tropical deforestation are nu- merous and severe. Rain forests are giant solar- powered engines that pump water, nutrients, and carbon dioxide through the biosphere. Water cap- tured by vegetation is stored in vines and roots, where it is slowly released to streams and rivers, continuing the evaporation cycle. When large tracts of rain forest are cleared, water cannot be readily stored, leading to alternate periods of drought and floods. Rain forests consist of lush, abundant growth, but the soil is deficient in nutrients and only marginally fertile. Although organic materials decompose rap- idly in warm, humid climates, heavy rains leach nutri- ents from the root zone. Plant life has adapted by rap- idly ingesting the nutrients as they become available; most nutrients are stored in the vegetation itself, not in the soil. When the land is cleared for agriculture or livestock, the necessary crop-sustaining nutrients are depleted within a few growing seasons. The biodiversity of the tropical rain forest is so im- mense thatless than 1 percent ofits millionsof species have been studied by scientists for their active constit- uents and their possible uses. Experts estimate that 137 plant, animal, and insect species are lost every day (50,000 species per year) because of deforestation. As the rain-forest species disappear, so do many possible cures for life-threatening diseases. If deforestation continues at current rates, nearly one-half of the world’s species of plants, animals, and microorgan- isms will be destroyed or severely threatened by the middle of the twenty-first century. Rain Forest Resources The Amazon rain forest covers close to 500 million hectares, encompassing areas in Brazil, Venezuela, Colombia, andthe eastern Andean region of Ecuador and Peru.More thanone-half of theworld’sestimated 10 million species of plants, animals, and insects live in the tropical rain forests; only 1.4 million of these species have even been named. The diversity of plant species in the Amazon rain forest is the highest on Earth. It is estimated that each hectare of rain forest contains more than 100 metric tons of living plants, including more thanthree hundredtypes of trees and six hundred species of plants. To date, some 438,000 species of plants of economicinterest have been regis- tered, but many more have yet to be cataloged. Approximately 80 percent of the developed world’s diet originated in tropical rain forests, including avo- cados, figs, oranges,lemons, grapefruit, bananas,gua- vas, pineapples, mangos, and tomatoes. Vegetables originating from the rain forest include corn, pota- toes, rice, squash, and yams.Rain-forest spicesinclude black pepper, cayenne, cinnamon, cloves, and ginger. Other popular rain-forest-derived foods include choc- olate, sugarcane, coffee, vanilla, and cashews. At least three thousand fruits are found in the rain forests; of these onlyabout twohundred are currently utilizedin the Western world, while the rain-forest Indians use several thousand. Rain-forest plants are rich in sec - 992 • Rain forests Global Resources ondary metabolites, particularly alkaloids, which pro- tect plants from disease and insect attacks and have medicinal benefits. Tropical rain forests are important sources of ge- netic material for improving existing crop plants or breeding new varieties. As the population size of a spe- cies shrinks, genetic diversity shrinks indirect propor- tion, because as a species diminishes in number, genes disappear even if the species survives. A reduc- tion of the gene pool renders a species less adaptable to changing environments and more susceptible to extinction, depriving future generations of poten- tially useful resources. Without periodic infusions of new germ plasm, crops bred specifically for humans, such as coffee, ba - nanas, and cocoa, cannot continue to produce high yields at low cost. As the products of generations of se - lective breeding, these crops contin - ually require the amalgamation of new geneticmaterial to maintain pro- ductivity and flavor, to counteract new diseases and insect strains, and to endure environmental stresses such as unusual cold or drought. A number of important crops, in- cluding cocoa, coffee, bananas, and sugarcane, have been saved from vi- ruses and other pathogens by be- ing crossbred with wild species that have acquired resistance naturally. Although crop diseases can be con- tained or eliminated by applying fun- gicides or pesticides, the cost is pro- hibitive. It is much less expensive, and more environmentally benign, to find a resistant strain of the same crop in one of the world’s remaining wild habitats. Future contributions from wild germ plasm, in addition to breed- ing new disease-resistant varieties of crops, might include the creation of hybrid perennial varieties of annual crops, eliminating annual plowing and sowing. Another possibility may be new varieties of conventional crops that could survive in conditions or environments that are presently unsuitable, extending the plants’ cul- tivation range. Rain forests also pro- vide opportunities for humans to develop and culti- vate entirely new crops. Many of the world’s staples are not necessarily the best possible sources of nutri- tion and protein; they were merely the crops most eas- ily cultivated by Neolithic humans. Because the developed world consumes enormous quantities of sugar annually, there is an urgent need for a sweetening agent without the potentially unde- sirable side effects of synthetic sweeteners. Natural sweeteners found in common fruits are problematic because many people already consume more of these than is healthy. However, a new class of nonfattening natural sweeteners made of protein compounds has been identified. At least one thousand times sweeter than sucrose, and with no known detrimental side ef - fects, these tropical sweeteners are viable replace - ments for thesucrose commonly addedto fooditems. Global Resources Rain forests • 993 Tropical rain forests, suchasthis one in Bali, Indonesia,have suffered from deforestation and wildlife depletion. (©Bruce Hempell/Dreamstime.com) Rain Forests: Pharmacopeia to the World There were an estimated 10 million Indians living in the Amazonian rain forest five centuries ago; today there are fewer than 200,000. As homelandsof indige- nous peoples continue to be destroyed by deforesta- tion, forcing the residents to leave, the key to finding new medicinal plants declines proportionately. Most shamans, with thousands of years of irreplaceable knowledge aboutmedicinal plants,are atleast seventy years oldand few have apprentices. Thus, when arain- forest shaman dies, it is as if a library has burned down; the failure to document this information is a tremendous economic and scientific loss to theindus- trialized world. Although 74 percent of the pharmaceutical drugs widely used today are plant-derived, very few rain- forest regions have been subjected to ethnobotanical analysis to identify and catalog the tropical biota. There are manyundiscovered biodynamiccompounds with unrealized potential for use inmodernmedicine residing in the rain forest, but to access the informa- tion, species must be preserved and studied. About one-quarter of all the medicines we use are derived from rain-forest ingredients. Curare, from a tropical vine, is used as an anesthetic and muscle relaxant dur- ing surgery. Quinine, from the cinchona tree, is used to treat malaria. A person with lymphocytic leukemia has a 99percent chancethatthe diseasewill go intore- mission because of treatment derived from the rosy periwinkle. Rain-forest plants also contain a plethora of yet uninvestigated biodynamic compounds with undis- covered potential foruse inmodern medicine.Future generations can hope to benefit from these sub- stances only if the species containing them are pre- served and studied. Of the hundreds of thousands of plant species inhabiting the rain forests, only a small fraction have been identified and studied, and the potentially beneficial pharmacologicalproperties of many of these are yet to be ascertained. The U.S. National Cancer Institute has identified three thousand plants that are active against cancer cells; 70 percent of these plants are found in the rain forest. Twenty-five percent of the active ingredients in today’s cancer-fighting drugs come from organisms found only in the rain forest. The rain forest and its immense undiscovered biodiversity hold the key to unlocking tomorrow’s cures for devastating diseases. Almost 90 percent of people in developing countries still rely on traditional medicine, based largely on different species of plants and animals, for their pri - mary health care. In the United States, 25 percent of prescriptions are filled with drugs whose active ingre- dients are extracted or derived from plants. More than 120 prescription drugs sold worldwide come from plant-derived sources from only ninety species of plants. Still more drugs are derived from animals and microorganisms. In the thousands of species of rain forest plants that have not been analyzed are many thousands of unknown plant chemicals that may well be useful in the continuing struggle against constantly evolving pathogens becoming resistant to mainstream drugs. If a cure for cancer or AIDS is found, it will probably originate in the rain forest. Destruction of the South American Rain Forest Once covering 14 percent of Earth’s land surface, rain forests have been reduced to only 6 percent be- cause of human activities. If this rate of extinction continues unabated, the last remaining rain forests could be gone by the middle of the twenty-first cen- tury. Tropical rain forests are disappearing at a rate four hundred times faster than at any time during the recent past. Every day, scores of plant, animal, and in- sect species become extinct; as these species disap- pear, possible cures for life-threatening diseases also vanish. Close to 1 hectare of rain forest disappears every second because shortsighted governments and land- owners believe only harvested timber or land cleared for ranching and farming has value. Another impor- tant contributor to the destruction of the Amazonian rain forest is the production and transportationof oil. The fragile rain-forest environment is easily contami- nated byleaks, spills,and the ejection of effluentsdur- ing pumping operations. Of even greater environ- mental impact is the destruction resulting from the oil companies’ practice of building roads from inhab- ited areas to the well sites.Pipelines arebuilt alongthe roads to carry the oil out of the jungle, but unem- ployed urban residents often follow the roads into the jungle and become squatters on adjoining land. They clear asmall section ofrain forest,using the slash-and- burn method, to eke out a living as subsistence farm- ers. However, when the rain forest is gone, so are most of the nutrients needed for agriculture; the land can- not sustain crops for long. The farmers then must move on and destroy more of the forest, regardless of the effects on the jungle or its native species. The tens 994 • Rain forests Global Resources of thousands of squatters engaging in this destructive practice contribute to the rapid rate of rain-forest de- struction. Although aware of the problem, the governments of most South American oil-exporting countries have a strong incentive for underplaying or ignoring the negative impact of oil production in their rain forests; their economies depend on oil, which is one of South America’s largest exports. Ultimately the demand for oil, driven by high consumption rates in industrial- ized nations, particularly the United States, is one of the primary factors causing rain-forest destruction. Too often environmentally unsustainable practices are subsidized as a means of reducing national debt. In the tropics, governments own or control nearly 80 percent of the rain forest, leaving it vulnerable to ad- ministrative policy. In addition to tax incentives and credit subsidies that guarantee large profits to private investors who convert forests to pastures and farms, governments allow private concessionaires to log the national forests on termsinherently destructive to the environment. Also, massive public expenditures on highways, dams, plantations, and farms, financed by multilateral development lending, destroy or convert large areas of forest for projects of questionable eco- nomic worth. Solutions The rain forest is being destroyed for short-term eco- nomic gain. Therefore a viable solution must offer economic incentives to governments and companies. If landowners, governments, and those dwelling in the rain forest were offered practical economic rea- sons for not razing the rain forest, it could be saved. This solution already exists and is presently being im- plemented in some locations. It has been demon- strated that if medicinal plants, fruits, nuts, rubber, and chocolate are harvested sustainably, the land has greater economic value and will provide more long- term profits in the future. Rain-forest land converted to cattle operations yields the landowner only a frac- tion per hectare of the dollars gained from logging the timber on that land. However, when sustainable resources are harvested, the land yields much more— and this annual income can continue indefinitely if sustainable practices are implemented. The true value of the rain forest is in sustainable resources, not the trees or grazing land. To harvest this wealth effec - tively, local people and indigenous tribes must be in - cluded, providing employmentas wellas aneconomic incentive for these people to protect and preserve the forests for future generations. To save the rain forest it is necessary that its inhabi- tants see that there is a consumer demand for sustain- able rain-forest products, markets that provide the economic incentive to protect their resources for long-term profits rather than short-term gain. When timber is harvested for short-term profits, the medici- nal plants and other important sustainable resources that thrive in this delicate ecosystem are destroyed. Creating a new source of income by harvesting me- dicinal plants andother sustainableresourcesrenders rain forests more valuable than when cut and burned and provides an improved standard of living for the local population. This solution can have a real and lasting impact; if every person in the industrialized world were to purchase only renewable and sustain- able rain-forest products and demand that the re- sources be harvested by local peoples, consumer de- mand alone would help ensure preservation. George R. Plitnik Further Reading Branford, Sue, and Oriel Glock. The Last Frontier: Fighting over Land in the Amazon. London: Zed Books, 1985. Bunnell, Fred L., and Glen B. Dunsworth. Forestry and Biodiversity: Learning How to Sustain Biodiversity in Managed Forests. Vancouver: UBC Press, 2009. Farnsworth, N. “Screening Plants for New Medi- cines.” In Biodiversity, edited by E. O. Wilson. Wash- ington, D.C.: National Academy Press, 1988. Holm-Nielson, L. B., C. Nielsen, and H. Balslev, eds. Tropical Forests: Botanical Dynamics, Speciation, and Diversity. London: Academic Press, 1989. Holzman, Barbara A. Tropical Forest Biomes. Westport, Conn.: Greenwood Press, 2008. Kozloff, Nikolas. No Rain in the Amazon: How South America’s ClimateChange Affects the EntirePlanet. New York: Palgrave Macmillan, 2010. London, Mark, and Brian Kelly. The Last Forest: The Amazon in the Age of Globalization. New York: Ran- dom House, 2007. Marent, Thomas. Rainforest. London: Dorling Kin- dersley, 2006. Montagnini, Florencia, and Carl F. Jordan. Tropical Forest Ecology: The Basis for Conservation and Manage- ment. New York: Springer, 2005. Morley, Robert J. Origin and Evolution of Tropical Rain Forests. New York: Wiley, 2000. Global Resources Rain forests • 995 Myers, Norman. A Wealth of Wild Species: Storehouse for Human Welfare. Boulder, Colo.: Westview Press, 1983. Place, Susan E., ed. Tropical Rainforests: Latin American Nature and Society in Transition. Rev. and updated ed. Wilmington, Del.: Scholarly Resources, 2001. Primack, Richard, and Richard Corlett. Tropical Rain Forests: An Ecological and Biogeographical Comparison. Malden, Mass.: Blackwell, 2005. Rain Forests of the World. New York: Marshall Caven- dish, 2002. Taylor, Leslie. The Healing Power of Rain Forest Herbs. Garden City, N.Y.: Square One, 2004. Wunder, Sven. Oil Wealth and the Fate of the Forest: A Comparative Study of Eight Tropical Countries. New York: Routledge, 2003. Web Site Blue Planet Biomes Tropical Rainforest http://www.blueplanetbiomes.org/rainforest.htm See also: Aggregates; Brazil; Deep ecology; Defores- tation; Ecosystems; Ecozones and biogeographic realms; Forest management; Genetic prospecting; Genetic resources; Greenhouse gases and global cli- mate change; Slash-and-burn agriculture; Species loss; United Nations Convention on Biological Diversity; World Bank. Ramsar Convention Category: Laws and conventions Date: Adopted February 2, 1971; entered into force December 21, 1975 Wetlands affect every level of life on Earth. Wetlands provide most of the usable water necessary for the con- tinuation of life of all forms.Humans and many other species take much of their food from the wetlands. The Ramsar Conventiion was designed to protect all types of wetlands. Background The Ramsar Convention is officially called the Con- vention on Wetlands of International Importance es - pecially as WaterfowlHabitat. Since the signing of the treaty in Ramsar, Iran, the convention has broadened its interests to all aspects of conservation of wetlands. It was the first worldwide treaty on the conservation of one resource, thewetlands in this case. The definition of wetlands has been a broad one and includes swamps, lakes, rivers, marshes, near-shore marine ar- eas, deltas, tidal flats, wet grasslands, peatlands, man- groves, coral reefs, estuaries, and man-made areas such as fish ponds, rice paddies,and salt pans.The de- struction or deterioration of wetlands will cause seri- ous environmental change to climate, biodiversity, water supply, and food supply. Provisions The three main goals of the Contracting Parties of the Convention are: tostrive for wiseuse ofall wetlands, to manage effectively the designated wetlands, and to cooperate on a global scale in matters concerning wetlands. The Conference of the Contracting Parties meets every three years to plan the policies for the next several years. The Standing Committee meets each year to continually monitor the use and preser- vation of wetlands. The daily activities are directed by the Ramsar Secretariat in Gland, Switzerland. There are five International Organization Partners which supply advice, materials, personnel, and funding. These organizations are: BirdLife International, the International Water Management Institute, Wetlands International, the World Conservation Union, and World Wide Fund for Nature International. A major aspect of the convention is the informational materi- als generated on wise use of wetlands. Contracting Parties can also obtaingrants and even expert person- nel and materials to use in projects to protect or reha- bilitate a wetlands area. Each contracting member commits to list wetlands sites, work to conserve those sites, cooperate internationally, create nature reserves in wetlands, and train personnel in conservation and rehabilitation of wetlands. The financial backing of the convention is a percentage contributed by each Contracting Party and from donations and grants. Impact on Resource Use As of 2009, more than1,830 wetlands, includingmore than 170 million hectares, were listed as designated wetlands on the Ramsar list. Contracting Parties are committed to manage such wetlands effectively. Con- tracting Parties who share a wetland have pledged to cooperate in the maintenance and protection of that wetland. The Ramsar Convention is a global treaty; as of 2009, 158 Contracting Parties were members. This 996 • Ramsar Convention Global Resources bodes well for the wetlands of the world; cooperation between certain countries is perhaps the first step to- ward a harmonious relationship. C. Alton Hassell Web Site The Ramsar Convention on Wetlands http://www.ramsar.org See also: Biodiversity; Ecosystems; Water; Water pol- lution and water pollution control; Wetlands; Wildlife biology. Rangeland Category: Ecological resources Rangeland encompasses a wide variety of land types, including grasslands, shrublands,marshes,and mead- ows as well as much desert and alpine land. Range- land is a valuable and resilient ecosystem resource that supports considerable plant and animal life. Background Rangeland generally refers to a kind of land rather than a use of that land. The Society for Range Manage- ment defines rangelands as “land on which the native vegetation (climax or natural potential) is predomi- nantly grasses,grasslike plants, forbs, or shrubs.” Rangeland, states the society, “includes lands revegetated naturally or artificially when routine manage- ment of that vegetation is accomplished mainly through manipulation of graz- ing” as well as “natural grasslands, savan- nas, shrublands, most deserts, tundra, alpine communities, coastal marshes and wet meadows.” Rangelands usually have some limi- tation on intensive agriculture, such as low and erratic precipitation, lack of soil fertility, shallow or rocky soil, or steep slopes. In addition to habitat for live- stock and wildlife grazing, rangelands serve other multiple-use functions, such as providing recreational opportunities, watersheds, mininglocations, and habi - tat for many animal species. Renewable natural resources associatedwith rangelands are plants and animals (and, in some senses, water). Nonrenew- able resourcesinclude mineralsand otherextractable materials. Variety of Rangelands Rangelands are extensive and extremely variable. As defined by the Society for Range Management, they occupy approximately 50 percent of the world’s total land surface and about 500 million hectares in the United States alone. Rangelands are home to count- less nomadic herders on nearly every continent. They vary from high-elevation alpine tundra and high- latitude Arctic tundra to tropical grasslands. The tall grass prairiesin the United States (nowmostly plowed for intensive agriculture) and the rich grasslands of eastern Africa are amongthe most productive. Range- lands grade into woodlands and forest as woody spe- cies and trees become more abundant. Some forests are grazed by wild and domestic animals, and the dis- tinction between rangeland and forest is often not clear. The other difficult distinction is between range- land and pastureland. Pastureland is generally im- proved byseeding, fertilization, orirrigation,whereas rangelands support nativeplants and havelittle inten- sive improvement. In the United States, rangeland improvements dur- ing the twenty years after World War II often included brush control, grazing management, seeding, and other practices, but rangelands were not irrigated.Af- Global Resources Rangeland • 997 Buffalo graze on rangeland in Crook County, Wyoming. (United States Depart - ment of Agriculture/Ron Nichols) . forests Global Resources of thousands of squatters engaging in this destructive practice contribute to the rapid rate of rain-forest de- struction. Although aware of the problem, the governments of. The Ramsar Convention is a global treaty; as of 2009, 158 Contracting Parties were members. This 996 • Ramsar Convention Global Resources bodes well for the wetlands of the world; cooperation between. tips of their brushes to produce a fine point, thus ingesting radium. In addition, water containing radium was often prescribed as a general tonic in the early part of the century. As a result of these