Rain forestsCategories: Ecological resources; plant and animal resources Rain forests are complicated tropical ecosystems with extremely high levels of biodiversity.. Background Tropical
Trang 1quartz crystals have been mined in Brazil, 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 as feedstock to culture (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 can be used to seed the culturing 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
H4SiO4) 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 occurs as the silica redeposits in the
wood Grasses such as bullrushes have considerable
sil-ica content and were chewed as primitive toothbrushes
by early settlers in the United 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 dust causes 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
Quartz crystals are used in electronics (United States Department of
Agri-culture)
Trang 2Large 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 the apparatus In the 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, not only in sand and rock but also in forms that
are valued as 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.” In Industrial 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 and physical prop-erties of; Mohs hardness scale; Orthosilicate minerals; Pumice; Sand and gravel; Silicates; Silicon
Trang 3Radium
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 pitchblende mined were in the 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 and other industrial and
scien-tific applications, and it has a role in the production of
environmental radiation
Technical Definition
Radium (symbol Ra) is a radioactive metallic element
with atomic number 88 and atomic weight 226.025
Located in Group IIA of the periodic table, it is
chemi-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
(U238) Because of its long half-life (4.5 billion years),
U238serves as an effectively constant source of Ra226
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 bebe-cause it decays successively to the particulate daughters polonium (Po218) and bismuth (Bi214) 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 found that only those substances 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, by precip-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 radium from 1898 to 1928 was only 500 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
Trang 4Obtaining 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 Carnotite is 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 remainder of the ore by
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 radbar-ium
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 its radioactive 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 casttest-ings 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 Buried Waste: The Rise 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 Their Discoveries San Francisco: W H Freeman,
1980
Selman, Joseph The Fundamentals of X-Ray and 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
Trang 5Rain 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
Tropical rain 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 annual rainfall
be-tween 127 and 660 centimeters and humidity bebe-tween
77 and 88 percent Seventy percent of the plants in the
rain forest are trees, with more types than in any other
region of the world Each region is individually
diver-sified; species found in one area may differ radically
from those in another section several kilometers 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 that less than 1 percent of its millions of 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, and the eastern Andean region of Ecuador and Peru More than one-half of the world’s estimated
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 than three hundred types of trees and six hundred species of plants To date, some 438,000 species of plants of economic interest 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 spices include 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 only about two hundred are currently utilized in the Western world, while the rain-forest Indians use several thousand Rain-forest plants are rich in
Trang 6ondary 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 in direct
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 genetic material 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 the sucrose commonly added to food items
Tropical rain forests, such as this one in Bali, Indonesia, have suffered from deforestation
and wildlife depletion (©Bruce Hempell/Dreamstime.com)
Trang 7Rain 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 homelands of
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 about medicinal plants, are at least seventy
years old and few have apprentices Thus, when a
rain-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 the
indus-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 many undiscovered biodynamic compounds
with unrealized potential for use in modern medicine
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 99 percent chance that the disease will go into
re-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 for use in modern 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 pharmacological properties
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 transportation of oil The fragile rain-forest environment is easily contami-nated by leaks, spills, and the ejection of effluents dur-ing pumpdur-ing 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 are built along the 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 a small section of rain 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
Trang 8of 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 terms inherently 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 employment as well as an economic
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 and other sustainable resources renders 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 Climate Change Affects the Entire Planet 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.
Trang 9Myers, 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 Waterfowl Habitat 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, the wetlands in this case The definition
of wetlands has been a broad one and includes swamps, lakes, rivers, marshes, neshore 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: to strive for wise use of all 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 obtain grants 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 than 1,830 wetlands, including more 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
Trang 10bodes 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 polpol-lution 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, mining locations, and
habi-tat for many animal species Renewable
natural resources associated with rangelands are plants and animals (and, in some senses, water) Nonrenew-able resources include minerals and other extractNonrenew-able 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 elevation alpine tundra and high-latitude Arctic tundra to tropical grasslands The tall grass prairies in the United States (now mostly plowed for intensive agriculture) and the rich grasslands of eastern Africa are among the most productive Range-lands grade into woodRange-lands 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 pasturerange-land Pasturerange-land is generally im-proved by seeding, fertilization, or irrigation, whereas rangelands support native plants and have little 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
Buffalo graze on rangeland in Crook County, Wyoming (United States
Depart-ment of Agriculture/Ron Nichols)