Encyclopedia of Global Resources part 36 pps

Earth Summit Categories: Laws and conventions; historical events and movements Date: June 3-14, 1992 The United Nations Conference on Environment and Development in Rio de Janeiro, Brazi

drought occurred in the region during the 1950’s, the

mid-1970’s, and the late 1980’s More vegetative cover

on the land, federal crop insurance, and more

knowl-edgeable farmers resulted in fewer dust storms, less

erosion, and less financial strain on farmers

David M Diggs

See also: Civilian Conservation Corps;

Desertifica-tion; Drought; Erosion and erosion control; Natural

Resources Conservation Service; Soil management;

Weather and resources

Dynamite

Category: Obtaining and using resources

The invention of dynamite has had an effect on the

procuring of coal, silver, gold, and any other materials

which are mined by tunneling.

Definition

Many different formulations are called dynamite, but

all are stabilized forms of nitroglycerine Dynamite is

an explosive that is highly dense so that a large

explo-sive power is available from a small volume of

mate-rial

Overview

Explosives have been a part of underground mining

ever since their discovery Until the mid-1800’s the

only explosive available was black powder, which was

lacking in power and created flames that constituted a

fire or dust explosion hazard in mines Nitroglycerine

was discovered by an Italian chemist, Ascanio

So-brero, in 1847 It is an oily organic liquid that is a

highly powerful explosive—and an extremely

unsta-ble chemical Temperature increases or mechanical

shock readily detonate nitroglycerine Although it

did find use in the mining industry, the hazard of

pre-mature explosions was extreme, and the industry

searched for an alternative

The material known as dynamite was discovered by Swedish inventor Alfred Nobel in 1867 After several years of experiments aimed at stabilizing nitroglycer-ine, Nobel found that when the liquid was absorbed

by diatomaceous earth the mixture was safe to handle and did not explode unless a blasting cap was used to initiate the reaction Nobel went on to commercialize the production of dynamite by building manufactur-ing facilities on a worldwide basis and thereby accu-mulating a large fortune Upon Nobel’s death, his will left a considerable portion of his fortune to establish the Nobel Prizes

Modern dynamite is a dry granular material that is fundamentally stabilized nitroglycerine It finds its greatest application in underground mining, where its high explosive power per volume is a desired qual-ity Other chemicals are mixed with the basic ingredi-ents to improve certain aspects of its performance Some particular formulations are designed to reduce the level of carbon monoxide and nitrogen dioxide that are produced in the explosion so that they do not create a hazard for miners Another form is of particu-lar use when high explosive power is needed at low op-erating temperatures

When packaged for use, the solid is packed into pa-per cylinders ranging from 2 to 20 centimeters in di-ameter and from 20 to 100 centimeters in length These sticks are placed in boreholes in the mine face, tamped into place, and fitted with an electrical deto-nator In coal mining a dynamite form that produces a slow shock wave is used so that the pieces of coal dis-lodged are relatively large For other deep mining purposes a form producing a fast shock wave is used to fragment the rock more thoroughly into smaller rock pieces that can be more easily processed Dynamite also finds a role in strip mining or pit mining, where its highly dense explosive power is not needed In these instances, it is used as a primer to detonate other, lower-cost, blasting agents

Kenneth H Brown

See also: Coal; Diatomite; Quarrying; Strip mining; Underground mining

Earth First!

Category: Organizations, agencies, and programs

Date: Established 1979

Earth First! comprises a group of activists from around

the world who employ radical, sometimes illegal tactics

to oppose environmental exploitation and are

dedi-cated to defending “Mother Earth.” The movement is a

network of autonomous groups with no central office,

paid officers, or decision-making boards Members are

motivated by a belief in biocentrism or deep ecology.

Background

Earth First! was founded in the United States by

Da-vid Foreman Calling itself a movement rather than

an organization, it is active in several countries Its

tools include grassroots organizing, litigation, civil

disobedience, and “monkeywrenching.” Earth First!

activists criticize the corporate structures and

image-consciousness of many environmental groups They

are committed to saving the wilderness and use the

slogan, “No compromise in the defense of Mother

Earth.”

Earth First! activists have adopted a variety of

mili-tant tactics, including drilling steel spikes into trees

(to make it impossible to cut them with mechanized

saws), adding sugar to the fuel tanks of bulldozers,

and chaining themselves to tree crushers The

orga-nization also uses theatrical demonstrations to keep

the public aware of environmental issues The Earth

First! journal, published six times per year,

chroni-cles the activities of the radical environmental

move-ment

Impact on Resource Use

One of Earth First!’s visions for the future is the

devel-opment of a 290-million-hectare wilderness system In

this area, priority would be given to the preservation

of indigenous species and ecosystems Stringent

guidelines would mandate no human habitation

ex-cept for those indigenous to the area and living a

tra-ditional lifestyle; no mechanized equipment; no

roads, buildings, or power lines; no logging, mining,

industry, agricultural development, or livestock

graz-ing; and the reintroduction of indigenous species and removal of all species not native to the area

Marian A L Miller

Web Site Earth First!

Earth First! Worldwide http://www.earthfirst.org/

See also: Environmental movement; Friends of the Earth International; Greenpeace; Sea Shepherd Con-servation Society

Earth Summit

Categories: Laws and conventions; historical events and movements

Date: June 3-14, 1992

The United Nations Conference on Environment and Development in Rio de Janeiro, Brazil, also known as the Earth Summit, focused on the environment and sustainable development Delegates from participating countries signed several documents—including Agenda 21, the Rio Declaration on Environment and Development, the Statement of Forest Principles, the United Nations Framework Convention on Climate Change, and the United Nations Convention on Bio-logical Diversity—regarding the management of global resources.

Background

In the 1960’s, the issue of environmental protection was gaining prominence in the United States and

in other developed countries As part of this political climate, the United Nations held the 1972 U.N Con-ference on the Human Environment in Stockholm, Sweden At the conference, 114 countries adopted a declaration on the management of global resources The United Nations Environment Programme was created after the conference to facilitate coordinated international action In the 1970’s and 1980’s, global

environmental problems such as overpopulation,

over-consumption, ozone depletion, and transboundary

air pollution increased These problems were

con-nected to other issues in world politics, including

globalization, the liberalization of world trade,

rela-tions between developed and developing countries,

and international resource production and use This

resulted in the creation of the World Commission

on Environment and Development in 1983, chaired

by former prime minister of Norway, Gro Harlem

Brundtland, to develop an international strategy to

address global environmental and resource problems

The Brundtland Commission’s efforts resulted in the

1987 report Our Common Future, which established the

discourse of sustainable development The report led

the United Nations to organize the Earth Summit in

1992

Provisions

Delegates from participating countries signed several

global provisions, such as Agenda 21, at the Earth

Summit Agenda 21 is a nonbinding plan of action to pursue international sustainable development, ad-dressing specific environmental issues and domestic policies The Rio Declaration on Environment and Development is a nonbinding set of twenty-seven principles to direct sustainable development efforts throughout the world Its main concern is sustainable development, but it recognizes the importance of healthy, functioning ecosystems The Statement of Forest Principles, another nonbinding statement adopted at the Earth Summit, pertains to the manage-ment of global forest resources and indicates a recog-nition of the differential obligations of developed and developing countries for the protection of the envi-ronment Also, signed at the Earth Summit was the United Nations Framework Convention on Climate Change, an international treaty to address the issue of global greenhouse-gas emissions Also signed was the United Nations Convention on Biological Diversity, the first treaty to address the issue and importance of the preservation of biodiversity through the

Brazilian president Fernando Collor de Mello signs the United Nations Convention on Climate Change at the 1992 Earth Summit, while U.N secretary general Boutros Boutros-Ghali, right, and other diplomats applaud (AP/Wide World Photos)

tion of ecosystems rather than through the protection

of independent species

Impact on Resource Use

The impact of the Earth Summit is related mainly

to the documents discussed above Agenda 21

im-pacted resource use by providing recommendations

for specific resource management policies, including

a call for the repeal of subsidies incongruent with

sustainable development It also requires countries to

include environmental factors in their statistical

ac-counting The United Nations Framework

Conven-tion on Climate Change did not in itself establish

lim-its to greenhouse-gas emissions, but it required the

subsequent adoption of limits like those in the 1997

Kyoto Protocol The Convention on Biological

Diver-sity led to the subsequent adoption of the Cartagena

Protocol on Biosafety, which allows for the regulation

of genetically modified organisms

Katrina Taylor

See also: Agenda 21; Biodiversity; Greenhouse gases

and global climate change; Kyoto Protocol; United

Nations climate change conferences; United Nations

Environment Programme; United Nations

Frame-work Convention on Climate Change

Earthquakes

Category: Geological processes and formations

Earthquakes result from fractures within the Earth

which are produced by a buildup of stress in brittle

rock When the frictional forces holding blocks of rock

together are overcome, the Earth moves and produces

cracks which can infill with minerals.

Definition

Earthquakes occur following the rapid release of

en-ergy stored in rocks Rocks beneath the Earth’s

sur-face are continually subjected to forces in all

direc-tions When the forces exceed the limits which the

rocks can sustain, they respond by either folding or

breaking If the forces are relatively rapid and the

rocks are brittle, then the rocks actually break The result is a shaking of the ground This shaking is most prominent on the Earth’s surface

Overview

An earthquake first originates at a point called the fo-cus, which is beneath the Earth’s surface This frac-ture, which begins at a point, grows from a micro-scopic crack into a large fault which can extend for many kilometers However, as mentioned, this frac-ture will be propagated only through brittle material

In other words, faults will not extend indefinitely into the Earth’s subsurface Nor will they extend indefi-nitely through brittle material, because there will be

a point where there is insufficient energy remaining

to break rock far removed from the initial source of

a fracture Focal depths of earthquakes occur over

a range of depths, extending from just below the Earth’s surface to a depth of approximately 700 kilo-meters Below this great depth rocks are no longer brittle and thus cannot break

In addition to the more obvious effects of seismic activity on the surface, earthquakes cause a consider-able amount of subsurface activity Seismic energy passing through brittle rock produces faults and cracks of varying sizes throughout the rock These fis-sures serve as conduits for fluids, which can move through the rock much more readily than they could before the rock was broken If the fluids contain dis-solved minerals, these will be deposited in concen-trated amounts Such is the case when molten rock rises below the surface and is injected into cracks Concentrated deposits of gold, silver, and other valu-able metals are commonly found filling cracks that were produced by earthquakes that occurred in the recent geologic past

Large-scale faulting can move massive blocks of rock closer to the Earth’s surface If these blocks are later exposed by erosion of the overlying material, new minerals are exposed Layers containing coal, limestone, and gravels become available for mining

David M Best

See also: Lithosphere; Pegmatites; Plate tectonics; Seismographic technology and resource exploitation

Earth’s crust

Category: Geological processes and formations

The earth’s crust is the outer hard layer of the planet.

The crust overlies the Earth’s mantle and is separated

from it by the Mohorovi5i5 discontinuity, or Moho.

There are two great classes of crust on Earth, oceanic

and continental, which differ in thickness,

composi-tion, density, age, mode of formacomposi-tion, and significance

for mineral resources.

Background

The earth consists of a nested set of spheres of

differ-ent composition and of decreasing density with

dis-tance from the center of the Earth The crust is the

outermost and lowest-density hard shell, significantly

less dense (2.7 to 3.0 grams per cubic centimeter)

than the underlying mantle (3.3 grams per cubic

centimeter) The earth’s two distinct types of crust—

continental and oceanic—differ in five fundamental

aspects: thickness, density, composition, age, and

mode of formation

Continental and Oceanic Crust

Continental crust is generally found beneath the

ex-posed parts of the Earth’s surface known as

conti-nents In addition, continental crust is submerged

and makes up the continental shelves and submerged

continental platforms Correspondingly, a larger

pro-portion of the Earth’s surface is composed of

conti-nental crust (40 percent) than is exposed above sea

level as continents (25 percent) Oceanic crust makes

up the floor of the oceans; in rare cases it rises above sea level, such as in Iceland and Ethiopia Our store

of nonrenewable natural resources is produced and kept in the crust Hydrothermal systems associated with oceanic crust formation at mid-ocean ridges pro-duce metal deposits Nearly all economic ore deposits are extracted from the continental crust Basins in the continental crust and along the continental margins are the principal sites for the formation and storage of oil and gas deposits

Typical continental crust is about 40 kilometers thick, has a density of about 2.7 grams per cubic centi-meter, and has a bulk composition similar to the volca-nic rock andesite; it is about 60 percent silicon diox-ide (SiO2) Continental crust as old as 4 billion years has been found, and 2.5 billion-year-old continen-tal crust is common The earth is about 4.5 billion years old, and continental crust from the Earth’s first

500 million years has not been preserved This con-trasts with the situation for Earth’s moon, where the lunar highlands preserve crust that formed shortly after the moon itself Oceanic crust is about 6 kilo-meters thick, has a density of about 3.0 grams per cu-bic centimeter, and has a bulk composition similar to the volcanic rock basalt (about 50 percent SiO2) Al-though ophiolites may be much older, the oldest in situ oceanic crust is about 170 million years old The large difference in age between oceanic and continental crust reflects the greater density of the former, which allows it to slide back into the mantle along subduction zones In contrast, buoyant conti-nental crust is difficult to subduct The formation of oceanic and continental crusts is fundamentally different as well: Oceanic crust forms by sea-floor spreading at mid-ocean ridges, whereas continental crust forms at island arcs lying above subduction zones (such as Japan or the Mariana Islands in the western Pacific) Although the area of oceanic crust is much larger than that of continental crust (60 percent versus 40 percent

of the Earth’s surface), the volume of continen-tal crust is much larger than that of oceanic crust (80 percent versus 20 percent)

Metal and Hydrocarbon Deposits The two types of crust play different roles in the formation of nonrenewable natural resources such as metallic ores and hydrocarbons Metal-lic ores are predominantly produced at

Chemical Composition of Earth’s Crust

gent or convergent plate boundaries—that is, where

oceanic crust is either produced or destroyed Vast

de-posits of manganese and cobalt exist on the deep-sea

floor in the form of manganese nodules

Hydrocar-bon deposits form principally in basins on continen-tal crust or beneath continencontinen-tal margins, at the boundary between oceanic and continental crust The configuration of continents may also be

50 40 30 20 10

0

Kilometers below surface

Kilometers

below sea

floor

10

8

6

4

2

0

Peridotite (Mantle) Gabbro

Basalt Sediments Water

Peridotite (Mantle)

Granulite Granodiorite

Upper crust

Lower crust Moho

Moho

Precambrian rock

Conrad discontinuity

Oceanic Crust Continental Crust

Comparison of Oceanic and Continental Crust

tant for controlling oil and gas deposits, because it can

cause the formation of restricted basins where

oxy-gen-poor waters allow organic matter to be preserved

and buried The relatively thin sedimentar y

se-quences typically deposited on oceanic crust are not

conducive to formation and preservation of

hydrocar-bon deposits

The distribution of mineral and hydrocarbon

re-sources is strongly controlled by the age of the crust

and the sedimentary basins that these harbor In spite

of the fact that the oceanic crust is the principal factory

for generating ore deposits, a minuscule proportion of

these are presently exploited, largely for economic

rea-sons Because of its age and mode of formation, the

continental crust acts as a warehouse for ore deposits

produced over Earth’s history, especially those

depos-its produced at convergent plate boundaries

Particu-larly rich ores are preserved in crust produced in the

first 2 billion years of Earth history, and those nations

which have large tracts of such ancient crust (among

them are Australia, Canada, Russia, and South Africa)

are blessed with especially rich metal deposits

Resource Frontiers

A wide range of mineral and hydrocarbon resources

are sought on all continents except Antarctica This

search benefits increasingly from abundant

techno-logical resources, including satellite remote sensing,

geophysical surveys, geochemical studies, and

tradi-tional field mapping, and from the tremendous

in-crease in computing power available to process large

and complex data sets These nonrenewable resources

are likely to be depleted in the future, leading to a rise

in prices that will reward exploitation of “frontier”

de-posits Resource frontiers pertaining to the Earth’s

crust include mining and drilling for oil deeper below

the continental surface, drilling for oil in deeper

water offshore, the mining of deep-sea resources, and

exploiting geothermal and hydrothermal resources

for energy, including the tremendous heat energy

stored in the deep continental crust and vented from

hydrothermal sites along the midocean ridges

Robert J Stern

Further Reading

Brown, Michael, and Tracy Rushmer, eds Evolution

and Differentiation of the Continental Crust New York:

Cambridge University Press, 2006

Condie, Kent C Earth as an Evolving Planetary System.

Boston: Elsevier Academic Press, 2005

Davis, Earl E., and Harry Elderfield, eds Hydrogeology

of the Ocean Lithosphere New York: Cambridge

Uni-versity Press, 2004

Fowler, C M R The Solid Earth: An Introduction to Global Geophysics 2d ed New York: Cambridge

Uni-versity Press, 2005

Grotzinger, John P., et al Understanding Earth 5th ed.

New York: W H Freeman, 2007

Mathez, Edmond A., and James D Webster The Earth Machine: The Science of a Dynamic Planet New York:

Columbia University Press, 2004

Rogers, John J W., and M Santosh Continents and Supercontinents New York: Oxford University Press,

2004

Taylor, Stuart Ross, and Scott M McLennan The Con-tinental Crust: Its Composition and Evolution, an Exam-ination of the Geochemical Record Preserved in Sedimen-tary Rocks Boston: Blackwell Scientific, 1985.

Web Site U.S Geological Survey The Earth’s Crust

http://earthquake.usgs.gov/research/structure/ crust/index.php

See also: Deep drilling projects; Geothermal and hy-drothermal energy; Hyhy-drothermal solutions and min-eralization; Igneous processes, rocks, and mineral de-posits; Lithosphere; Marine vents; Oil and natural gas distribution; Oil and natural gas reservoirs; Ophio-lites; Plate tectonics; Plutonic rocks and mineral de-posits; Seafloor spreading; Volcanoes

Earthwatch Institute

Category: Organizations, agencies, and programs Date: Established 1971

Earthwatch is an international nonprofit organiza-tion that advocates research and scientific literacy to help resolve environmental issues such as sustainable resource management Earthwatch supports scientific research projects and assigns volunteers to those proj-ects; builds networks to share expedition-based curricu-lums and lessons; collaborates with other conservation and environmental organizations; and solicits corpo-rate partners and private individuals to help promote

a sustainable environment.

Founded in 1971, in Boston, Massachusetts,

Earth-watch Institute began with four Smithsonian scientists

and small teams of volunteers Earthwatch was

estab-lished as government funds for scientific research

de-creased The organization sought a funding model

that would bridge research with action to increase

public scientific literacy and involvement

Earthwatch Institute is the world’s largest

environ-mental volunteer nonprofit organization The

mis-sion of Earthwatch is to engage people worldwide in

scientific field research and education to promote the

understanding and action necessary for a sustainable

environment The Earthwatch community includes

research scientists, educators, students, global

mem-bers, volunteers, collaborating conservation

organi-zations, and corporate partners

Earthwatch Institute is a public charity under the

U.S Internal Revenue Code The organization has

headquarters in Australia, Belize, Costa Rica, England,

Japan, Kenya, and the United States

Impact on Resource Use

Earthwatch prioritizes and supports effective

scien-tific research that focuses on sustainable resource

management, climate change, oceans, and

sustain-able cultures Such projects include data on species,

habitats, and protected areas Scientific results are

published worldwide in scholarly journals and shared

with partner organizations, government agencies,

and policy makers

Earthwatch research results have confirmed that

sustainable resource management is crucial not only

to social and economic development but also to

un-derstanding ecosystem complexities Such studies

in-clude the Amazon Riverboat Exploration, which

found that since local communities have been actively

involved in the management of the Pacaya-Samiria

National Reserve in the Peruvian Amazon there has

been a decrease in hunting and an increase in

popula-tions of certain wildlife species

Other Earthwatch research focuses on ways that

various species are affected by climate change and

may suggest ways to mitigate negative impacts, such as

those caused by human activities In 2006, James

Crabbe received an award for his outstanding

re-search on coral reefs in Jamaica and Belize He uses a

remotely operated vehicle (ROV) to obtain digital

im-ages and measure growth of coral at depths that are

difficult or impossible to reach by diving His research

results include findings that the rising Jamaican water temperature has caused a measurable decline in coral cover

Earthwatch supports research on the stability and productivity of life in oceans and coastal regions In

2007, Earthwatch completed the first baseline survey

of species inhabiting the subtidal and intertidal zones

of the Seychelles The study had the support of the Mitsubishi Corporation Research data, including photographic documentation, were shared with the Seychelles government, local communities, and con-servation groups With assistance from project scien-tists, teacher volunteers in the Seychelles and United Kingdom have developed ecology curriculum re-sources for educational use

An Earthwatch focus on both current and past sus-tainable cultures contributes to a better understand-ing of human interaction with the environment Re-search on ancient civilizations, such as that which inhabited the Rapa Nui, or Easter Island, provides assessments on behavioral change, attitudes, and ad-aptation Chris Stevenson has led the project for ap-proximately two decades Research findings include information linking climatic changes with changes

in farming that may be helpful in analyzing modern environmental problems

June Lundy Gastón

Web Site EarthWatch http://www.earthwatch.org See also: Biodiversity; Biotechnology; Resources for the Future; Sustainable development

Ecology

Category: Scientific disciplines

Ecology is the scientific study of the interrelationships among organisms—including their habitats, distribu-tion, and abundance—and the relationships of these organisms with their environment, known as bio-nomics From a global perspective, ecology concerns many issues that affect the interaction and connec-tions between living and nonliving environments, and, hence, the availability, distribution, and use of global resources.

In the 1860’s, Ernst Haeckel, a German scientist,

coined the word “ecology” based on the Greek word

oikos, which means “house.” The terminology is apt,

because ecology focuses on the complex

environmen-tal conditions that form organisms’ habitats

His-torically, ecology was rooted in natural history, which

in the 1800’s sought to describe the diversity of life

and evolutionary adaptations to the environment In

modern usage, ecology includes the study of the

inter-actions among organisms—such as humans, animals,

insects, microbes, and plants—and their physical or

abiotic environment The abiotic environment

con-cerns factors such as climate (air and temperature),

hydrology (water), geological substrate (soil), light,

and natural disasters that affect the environment The

abiotic factors are essential for sustaining the life of

organisms

Ecology also involves the study of biotic

environ-mental components that influence habitats and the

distribution and abundance of species of organisms

in geographic space and time The interaction

be-tween living organisms and the nonliving

environ-ment in a self-contained area is known as an

ecosys-tem Ecologists study processes such as how energy

and matter move though interrelated ecosystems like

ponds, forest glades, or rocks with moss growing on

them Maintaining an ecosystem requires the proper

balance of air, water, soil, sunlight, minerals, and

nu-trients

Ecological Levels

Modern ecology is interdisciplinary and is based on

multiple classifications Descriptive unit

classifica-tions based on the study of organisms and processes

start with the simplest and build to the most complex,

from individuals to populations, species,

communi-ties, ecosystems, and biomes

• Physiological ecology, the simplest classification,

concerns the interaction of individual organisms

with their life-sustaining abiotic environment and

the impact of biotic components on their habitats

• Population ecology is the study of the interaction of

individuals of different species (whether

bacte-rium, plant, or animal) that occupy the same

loca-tion and are genetically different from other such

groups

• Community ecologists analyze the interaction of

in-terdependent species populations living within a

given habitat or area, known as an ecological com-munity

• Ecosystem ecology includes the nonliving environ-ment and concerns decomposition of living organ-isms and intake of inorganic materials into living organisms In other words, ecosystem ecologists study the flow of energy and the cycling of nutrients through the abiotic and biotic environments of in-teracting ecological communities

• The interaction of multiple ecosystems with one an-other is known as a biome Some familiar biomes in-clude coniferous forests, rain forests, tundra re-gions, deserts, coral reefs, and oceans

• Finally, scientists involved in biosphere ecology study the interaction of all matter and living organ-isms on the planet

Ecological Subfields The terminology used for other ecological classifica-tions emphasizes the interdisciplinary nature of ecol-ogy Paleoecology, for example, involves archaeology

in the study of ancient remains and fossils in order to analyze the interrelationships of historic organisms and reconstruct ancient ecosystems Using evolution-ary theory, behavioral ecologists consider the roles of behavior in enabling organisms to adapt to new and changed environments In systems ecology, scientists use systems theory to manage energy flows and bio-geochemical cycles in ecosystems With some basis in anthropology, political ecologists seek equilibrium in political, economic, and social decision making that impacts the environment Landscape ecologists con-duct spatial analyses and examine processes and in-terrelationships of ecosystems over large, regional geographic areas Global ecology is the study of inter-relationships between organisms and their environ-ment on a global scale

Genetic Ecology Two emerging specialty subfields of ecology are ge-netic and evolutionary ecology In gege-netic ecology, scientists study genetic variations in species that lead

to the evolution of new species or to the adaptation of existing species to new or changed environments These new or changed environments may be the re-sult of many factors, including abiotic changes, such

as an increase or decrease in temperature; increased predation of a species, including overhunting or over-fishing; or an unsustainable increase in population When the environment changes or ecosystems are

turbed, species must adapt or face extinction Genetic

ecology considers genetic factors that allow some

spe-cies to adapt to and survive environmental changes

more easily In some recent studies of plant species

sci-entists used genetic ecology to analyze how quickly

specific plants migrate and adapt to new habitats in

re-sponse to climate change Although earlier

predic-tions indicated that plant migration would keep up

with environmental change, recent studies indicate

that migration will be slower than originally believed

Genetic ecology is also an important tool in studying

animal species as well as managing wild and captive

animal populations and improving population health

Genetic ecologists are involved in genetic

engi-neering in order to assess the relationship between

genetics of a species and the ecosystem that supports

the survival of that species One argument is that an

organism’s genetic structure fits exactly with the

ex-ternal ecosystem that supports its survival, especially

the external and life-sustaining oxygen-carbon

diox-ide system The concern is that interspecies genetic

engineering will upset the delicate ecological balance

that allows a species to maintain its existence within

a specific ecosystem and will adversely affect the con-tinuous and systematic reproduction of ecosystems supported by symbiotic relationships, such as an or-ganism’s energy production and processing systems Unless an organism is able to evolve by adapting its ge-netic structures to changes in an ecosystem, it is un-likely to survive An example of genetic engineering that may adversely affect the environment and other living organisms involves pest-resistant corn Pollen of

some corn genetically modified to code for Bacillus thuringiensis was initially thought to threaten

mon-arch butterflies Later studies showed this not to be the case, but a greater concern emerged: So-called Bt corn may encourage the development of resistant pests, which could then threaten corn crops Until the emergence of a better understanding of the relation-ships between genetic structures of all living organ-isms and the relationships of organorgan-isms to ecosystems, genetic engineering may present serious dangers

Evolutionary Ecology Evolutionary ecology brings together ecology, biol-ogy, and evolution Evolutionary ecologists look at the

The Blue Ridge Mountains, part of the Appalachian Mountains in the eastern United States, represent both biological and political issues that concern the modern ecologist (AP/Wide World Photos)