From the glossary of the assigned textbook.
Chapter 2
Milky Way Galaxy (p. 44) A flattened, disk-shaped mass in space estimated to contain up to 400
billion stars; a barred-spiral galaxy; includes our Solar System.
gravity (p. 45) The mutual force exerted by the masses of objects that are attracted one to
another and produced in an amount proportional to each object’s mass.
planetesimal hypothesis (p. 45) Proposes a process by which early protoplanets formed from
the condensing masses of a nebular cloud of dust, gas, and icy comets; a formation process
now being observed in other parts of the galaxy.
speed of light (p. 45) Specifically, 299 792 kilometers per second, or more than 9.4 trillion
kilometers per year—a distance known as a light-year; at light speed, Earth is 8 minutes and 20
seconds from the Sun.
perihelion (p. 45) The point of Earth’s closest approach to the Sun in its elliptical orbit, reached
on January 3 at a distance of 147 255 000 km; variable over a 100 000-year cycle. (Compare
Aphelion.)
aphelion (p. 45) The point of Earth’s greatest distance from the Sun in its elliptical orbit; reached
on July 4 at a distance of 152 083 000 km; variable over a 100 000-year cycle. (Compare
Perihelion.)
fusion (p. 45) The process of forcibly joining positively charged hydrogen and helium nuclei
under extreme temperature and pressure; occurs naturally in thermonuclear reactions within
stars, such as our Sun.
sunspots (p. 46) Magnetic disturbances on the surface of the Sun, occurring in an average
11-year cycle; related flares, prominences, and outbreaks produce surges in solar wind.
solar wind (p. 46) Clouds of ionized (charged) gases emitted by the Sun and travelling in all
directions from the Sun’s surface. Effects on Earth include auroras, disturbance of radio signals,
and possible influences on weather.
magnetosphere (p. 47) Earth’s magnetic force field, which is generated by dynamo-like motions
within the planet’s outer core; deflects the solar wind flow toward the upper atmosphere above
each pole.
aurora (p. 47) A spectacular glowing light display in the ionosphere, stimulated by the interaction
of the solar wind with principally oxygen and nitrogen gases and few other atoms at high
latitudes; called aurora borealis in the Northern Hemisphere and aurora australis in the
Southern Hemisphere.
electromagnetic spectrum (p. 47) All the radiant energy produced by the Sun placed in an
ordered range, divided according to wavelengths.
wavelength (p. 48) A measurement of a wave; the distance between the crests of successive
waves. The number of waves passing a fixed point in 1 second is called the frequency of the
wavelength.
thermopause (p. 49) A zone approximately 480 km in altitude that serves conceptually as the
top of the atmosphere; an altitude used for the determination of the solar constant.
insolation (p. 49) Solar radiation that is incoming to Earth systems.
solar constant (p. 49) The amount of insolation intercepted by Earth on a surface perpendicular
to the Sun’s rays when Earth is at its average distance from the Sun; a value of 1372 W · m−2
(1.968 calories · cm−2) per minute; averaged over the entire globe at the thermopause.
subsolar point (p. 49) The only point receiving perpendicular insolation at a given moment—that
is, the Sun is directly overhead. (See Declination.)
altitude (p. 52) The angular distance between the horizon (a horizontal plane) and the Sun (or
any point in the sky).
declination (p. 52) The latitude that receives direct overhead (perpendicular) insolation on a
particular day; the subsolar point migrates annually through 47° of latitude between the Tropics
of Cancer (23.5° N) and Capricorn (23.5° S).
daylength (p. 52) Duration of exposure to insolation, varying during the year depending on
latitude; an important aspect of seasonality.
sunrise (p. 52) That moment when the disk of the Sun first appears above the horizon.
sunset (p. 52) That moment when the disk of the Sun totally disappears below the horizon.
revolution (p. 53) The annual orbital movement of Earth about the Sun; determines the length of
the year and the seasons.
rotation (p. 53) The turning of Earth on its axis, averaging about 24 hours in duration;
determines day–night relation; counterclockwise when viewed from above the North Pole and
from west to east, or eastward, when viewed from above the equator.
axis (p. 53) An imaginary line, extending through Earth from the geographic North Pole to the
geographic South Pole, around which Earth rotates.
circle of illumination (p. 53) The division between light and dark on Earth; a day–night great
circle.
axial tilt (p. 54) Earth’s axis tilts 23.5° from a perpendicular to the plane of the ecliptic (plane of
Earth’s orbit around the Sun).
plane of the ecliptic (p. 54) A plane (flat surface) intersecting all the points of Earth’s orbit.
axial parallelism (p. 54) Earth’s axis remains aligned the same throughout the year (it “remains
parallel to itself”); thus, the axis extended from the North Pole points into space always near
Polaris, the North Star.
Tropic of Cancer (p. 55) The parallel that marks the farthest north the subsolar point migrates
during the year; 23.5° N latitude. (See Tropic of Capricorn, Summer [June] solstice.)
Tropic of Capricorn (p. 55) The parallel that marks the farthest south the subsolar point migrates
during the year; 23.5° S latitude. (See Tropic of Cancer, winter [December] solstice.)
December (winter) solstice (p. 55) The time when the Sun’s declination is at the Tropic of
Capricorn, at 23.5° S latitude, December 21–22 each year. The day is 24 hours long south of
the Antarctic Circle. The night is 24 hours long north of the Arctic Circle. (Compare Summer
[June] solstice.)
Arctic Circle (p. 55) This latitude (66.5° N) denotes the southernmost parallel (in the Northern
Hemisphere) that experiences a 24-hour period of darkness in winter or daylight in summer.
March (vernal) equinox (p. 55) The time around March 20–21 when the Sun’s declination
crosses the equatorial parallel (0° latitude) and all places on Earth experience days and nights
of equal length. The Sun rises at the North Pole and sets at the South Pole. (Compare
Autumnal [September] equinox.)
June (summer) solstice (p. 55) The time when the Sun’s declination is at the Tropic of Cancer, at
23.5° N latitude, June 20–21 each year. The night is 24 hours long south of the Antarctic Circle.
The day is 24 hours long north of the Arctic Circle. (Compare Winter [December] solstice.)
Antarctic Circle (p. 55) This latitude (66.5° S) denotes the northernmost parallel (in the Southern
Hemisphere) that experiences a 24-hour period of darkness in winter or daylight in summer.
September (Autumnal) equinox (p. 55) The time around September 22–23 when the Sun’s
declination crosses the equatorial parallel (0° latitude) and all places on Earth experience days
and nights of equal length. The Sun rises at the South Pole and sets at the North Pole.
(Compare Vernal [March] equinox.)
Chapter 3
air (p. 66) A simple mixture of gases (N, O, Ar, CO2, and trace gases) that is naturally
odourless, colourless, tasteless, and formless, blended so thoroughly that it behaves as if it
were a single gas.
exosphere (p. 66) An extremely rarefied outer atmospheric halo beyond the thermopause at an
altitude of 480 km; probably composed of hydrogen and helium atoms, with some oxygen atoms
and nitrogen molecules present near the thermopause.
air pressure (p. 66) Pressure produced by the motion, size, and number of gas molecules in the
air and exerted on surfaces in contact with the air; an average force at sea level of 1 kg · cm−3.
Normal sea-level pressure, as measured by the height of a column of mercury (Hg), is
expressed as 1013.2 millibars, 760 mm of Hg, or 29.92 inches of Hg. Air pressure can be
measured with mercury or aneroid barometers (see listings for both).
heterosphere (p. 67) A zone of the atmosphere above the mesopause, from 80 km to 480 km in
altitude; composed of rarefied layers of oxygen atoms and nitrogen molecules; includes the
ionosphere.
homosphere (p. 67) A zone of the atmosphere from Earth’s surface up to 80 km, composed of
an even mixture of gases, including nitrogen, oxygen, argon, carbon dioxide, and trace gases.
thermosphere (p. 69) A region of the heterosphere extending from 80 to 480 km in altitude;
contains the functional ionosphere layer.
thermopause (p. 69) A zone approximately 480 km in altitude that serves conceptually as the
top of the atmosphere; an altitude used for the determination of the solar constant.
kinetic energy (p. 69) The energy of motion in a body; derived from the vibration of the body’s
own movement and stated as temperature.
mesosphere (p. 70) The upper region of the homosphere from 50 to 80 km above the ground;
designated by temperature criteria; atmosphere extremely rarified.
noctilucent cloud (p. 70) A rare, shining band of ice crystals that may glow at high latitudes long
after sunset; formed within the mesosphere, where cosmic and meteoric dust act as nuclei for
the formation of ice crystals.
stratosphere (p. 71) That portion of the homosphere that ranges from 20 to 50 km above Earth’s
surface, with temperatures ranging from −57°C at the tropopause to 0°C at the stratopause. The
functional ozonosphere is within the stratosphere.
troposphere (p. 71) The home of the biosphere; the lowest layer of the homosphere, containing
approximately 90% of the total mass of the atmosphere; extends up to the tropopause;
occurring at an altitude of 18 km at the equator, at 13 km in the middle latitudes, and at lower
altitudes near the poles.
tropopause (p. 71) The top zone of the troposphere defined by temperature; wherever –57°C
occurs.
normal lapse rate (p. 71) The average rate of temperature decrease with increasing altitude in
the lower atmosphere; an average value of 6.4 C° per km, or 1000 m. (Compare Environmental
lapse rate.)
environmental lapse rate (p. 71) The actual rate of temperature decrease with increasing
altitude in the lower atmosphere at any particular time under local weather conditions; may
deviate above or below the normal lapse rate of 6.4 C° per km, or 1000 m. (Compare Normal
lapse rate.)
ionosphere (p. 71) A layer in the atmosphere above 80 km (50 mi) where gamma, X-ray, and
some ultraviolet radiation is absorbed and converted into longer wavelengths and where the
solar wind stimulates the auroras.
ozonosphere, ozone layer (p. 72) A layer of ozone occupying the full extent of the stratosphere
(20 to 50 km above the surface); the region of the atmosphere where ultraviolet wavelengths of
insolation are extensively absorbed and converted into heat.
chlorofluorocarbons (CFCs) (p. 74) A manufactured molecule (polymer) made of chlorine,
fluorine, and carbon; inert and possessing remarkable heat properties; also known as one of the
halogens. After slow transport to the stratospheric ozone layer, CFCs react with ultraviolet
radiation, freeing chlorine atoms that act as a catalyst to produce reactions that destroy ozone;
manufacture banned by international treaties.
pollutants (p. 73) Natural or human-caused gases, particles, and other substances in the
troposphere that accumulate in amounts harmful to humans or to the environment.
aerosols (p. 73) Small particles of dust, soot, and pollution suspended in the air.
anthropogenic atmosphere (p. 76) Earth’s future atmosphere, so named because humans
appear to be the principal causative agent.
carbon monoxide (CO) (p. 76) An odourless, colorless, tasteless combination of carbon and
oxygen produced by the incomplete combustion of fossil fuels or other carbon-containing
substances; toxicity to humans is due to its affinity for hemoglobin, displacing oxygen in the
bloodstream.
photochemical smog (p. 76) Air pollution produced by the interaction of ultraviolet light, nitrogen
dioxide, and hydrocarbons; produces ozone and PAN through a series of complex
photochemical reactions. Automobiles are the major source of the contributive gases.
volatile organic compounds (VOCs) (p. 76) Compounds, including hydrocarbons, produced by
the combustion of gasoline, from surface coatings, and from combustion to produce electricity;
participate in the production of PAN through reactions with nitric oxides.
nitrogen dioxide (NO2) (p. 77) A noxious (harmful) reddish-brown gas produced in combustion
engines; can be damaging to human respiratory tracts and to plants; participates in
photochemical reactions and acid deposition.
peroxyacetyl nitrates (PANs) (p. 77) A pollutant formed from photochemical reactions involving
nitric oxide (NO) and volatile organic compounds (VOCs). PAN produces no known human
health effect, but is particularly damaging to plants.
industrial smog (p. 80) Air pollution associated with coal-burning industries; it may contain sulfur
oxides, particulates, carbon dioxide, and exotics.
sulfur dioxide (SO2) (p. 80) A colourless gas detected by its pungent odour; produced by the
combustion of fossil fuels, especially coal, that contain sulfur as an impurity; can react in the
atmosphere to form sulfuric acid, a component of acid deposition.
sulfate aerosols (p. 80) Sulfur compounds in the atmosphere, principally sulfuric acid; principal
sources relate to fossil fuel combustion; scatter and reflect insolation.
particulate matter (PM) (p. 80) Dust, dirt, soot, salt, sulfate aerosols, fugitive natural particles, or
other material particles suspended in air.
temperature inversion (p. 81) A reversal of the normal decrease of temperature with increasing
altitude; can occur anywhere from ground level up to several thousand metres; functions to
block atmospheric convection and thereby trap pollutants.
Chapter 4
transmission (p. 92) The passage of shortwave and longwave energy through space, the
atmosphere, or water.
heat (p. 93) The flow of kinetic energy from one body to another because of a temperature
difference between them.
sensible heat (p. 93) Heat that can be measured with a thermometer; a measure of the
concentration of kinetic energy from molecular motion.
conduction (p. 93) The slow molecule-to-molecule transfer of heat through a medium, from
warmer to cooler portions.
convection (p. 93) Transfer of heat from one place to another through the physical movement of
air; involves a strong vertical motion. (Compare Advection.)
advection (p. 93) Horizontal movement of air or water from one place to another. (Compare
Convection.)
scattering (p. 94) Deflection and redirection of insolation by atmospheric gases, dust, ice, and
water vapour; the shorter the wavelength, the greater the scattering; thus, skies in the lower
atmosphere are blue.
diffuse radiation (p. 94) The downward component of scattered incoming insolation from clouds
and the atmosphere.
refraction (p. 95) The bending effect on electromagnetic waves that occurs when insolation
enters the atmosphere or another medium; the same process disperses the component colors
of the light passing through a crystal or prism.
mirage (p. 95) A refraction effect when an image appears near the horizon where light waves
are refracted by layers of air at different temperatures (and consequently of different densities).
reflection (p. 96) The portion of arriving insolation that is returned directly to space without being
absorbed and converted into heat and without performing any work. (See Albedo.)
albedo (p. 96) The reflective quality of a surface, expressed as the percentage of reflected
insolation to incoming insolation; a function of surface color, angle of incidence, and surface
texture.
absorption (p. 96) Assimilation and conversion of radiation from one form to another in a
medium. In the process, the temperature of the absorbing surface is raised, thereby affecting
the rate and wavelength of radiation from that surface.
global dimming (p. 97) The decline in sunlight reaching Earth’s surface due to pollution,
aerosols, and clouds.
greenhouse effect (p. 98) The process whereby radiatively active gases (carbon dioxide, water
vapour, methane, and CFCs) absorb and emit the energy at longer wavelengths, which are
retained longer, delaying the loss of infrared to space. Thus, the lower troposphere is warmed
through the radiation and re-radiation of infrared wavelengths. The approximate similarity
between this process and that of a greenhouse explains the name.
greenhouse gases (p. 98) Gases in the lower atmosphere that delay the passage of longwave
radiation to space by absorbing and reradiating specific wavelengths. Earth’s primary
greenhouse gases are carbon dioxide, water vapour, methane, nitrous oxide, and fluorinated
gases, such as chlorofluorocarbons (CFCs).
cloud-albedo forcing (p. 98) An increase in albedo (the reflectivity of a surface) caused by
clouds due to their reflection of incoming insolation.
cloud-greenhouse forcing (p. 98) An increase in greenhouse warming caused by clouds
because they can act like insulation, trapping longwave (infrared) radiation.
jet contrails (p. 98) Condensation trails produced by aircraft exhaust, particulates, and water
vapour can form high cirrus clouds, sometimes called false cirrus clouds.
microclimatology (p. 104) The study of local climates at or near Earth’s surface or up to that
height above the Earth’s surface where the effects of the surface are no longer determinative.
net radiation (NET R) (p. 105) The net all-wave radiation available at Earth’s surface; the final
outcome of the radiation balance process between incoming shortwave insolation and outgoing
longwave energy.
urban heat island (UHI) (p. 107) An urban microclimate that is warmer on average than areas in
the surrounding countryside because of the interaction of solar radiation and various surface
characteristics.
dust dome (p. 109) A dome of airborne pollution associated with every major city; may be blown
by winds into elongated plumes downwind from the city.
Chapter 5
temperature (p. 119) A measure of sensible heat energy present in the atmosphere and other
media; indicates the average kinetic energy of individual molecules within a substance.
land–water heating differences (p. 124) Differences in the degree and way that land and water
heat, as a result of contrasts in transmission, evaporation, mixing, and specific heat capacities.
Land surfaces heat and cool faster than water and have continentality, whereas water provides
a marine influence.
transparency (p. 125) The quality of a medium (air, water) that allows light to easily pass
through it.
specific heat (p. 125) The increase of temperature in a material when energy is absorbed; water
has a higher specific heat (can store more heat) than a comparable volume of soil or rock.
Gulf Stream (p. 126) A strong, northward-moving, warm current off the east coast of North
America, which carries its water far into the North Atlantic.
marine effect (p. 126) A quality of regions that are dominated by the moderating effect of the
ocean and that exhibit a smaller range of minimum and maximum temperatures, both daily and
annually, than do continental stations. (See Continental effect, Land–water heating difference.)
continental effect (p. 126) A quality of regions that lack the temperature-moderating effects of
the ocean and that exhibit a greater range of minimum and maximum temperatures, both daily
and annually, than do marine stations. (See Marine effect, Land–water heating difference.)
isotherm (p. 130) An isoline connecting all points of equal temperature.
thermal equator (p. 131) The isoline on an isothermal map that connects all points of highest
mean temperature.
heat wave (p. 136) A prolonged period of abnormally high temperatures, usually, but not always,
in association with humid weather.
Chapter 19
ecosystem (p. 606) A self-regulating association of living plants and animals and their nonliving
physical and chemical environments.
ecology (p. 606) The science that studies the relations between organisms and their
environment and among various ecosystems.
biogeography (p. 606) The study of the distribution of plants and animals and related
ecosystems; the geographical relationships with their environments over time.
producer (p. 607) Organism (plant) in an ecosystem that uses carbon dioxide as its sole source
of carbon, which it chemically fixes through photosynthesis to provide its own nourishment; also
called an autotroph. (Compare Consumer.)
vascular plant (p. 608) A plant having internal fluid and material flows through its tissues; almost
270 000 species exist on Earth.
stomata (p. 608) Small openings on the undersides of leaves through which water and gasses
pass.
photosynthesis (p. 608) The process by which plants produce their own food from carbon
dioxide and water, powered by solar energy. The joining of carbon dioxide and hydrogen in
plants, under the influence of certain wavelengths of visible light; releases oxygen and produces
energy-rich organic material, sugars, and starches. (Compare Respiration.)
chlorophyll (p. 608) A light-sensitive pigment that resides within chloroplasts (organelles) in leaf
cells of plants; the basis of photosynthesis.
respiration (p. 609) The process by which plants oxidize carbohydrates to derive energy for their
operations; essentially, the reverse of the photosynthetic process; releases carbon dioxide,
water, and heat energy into the environment. (Compare Photosynthesis.)
net primary productivity (p. 609) The net photosynthesis (photosynthesis minus respiration) for a
given community; considers all growth and all reduction factors that affect the amount of useful
chemical energy (biomass) fixed in an ecosystem.
biomass (p. 609) The total mass of living organisms on Earth or per unit area of a landscape;
also, the weight of the living organisms in an ecosystem.
consumer (p. 609) Organism in an ecosystem that depends on producers (organisms that use
carbon dioxide as their sole source of carbon) for its source of nutrients; also called a
heterotroph. (Compare Producer.)
biogeochemical cycle (p. 611) One of several circuits of flowing elements and materials (carbon,
oxygen, nitrogen, phosphorus, water) that combine Earth’s biotic (living) and abiotic (nonliving)
systems; the cycling of materials is continuous and renewed through the biosphere and the life
processes.
dead zone (p. 613) Are of low-oxygen conditions and limited marine life caused by excessive
nutrient inputs in coastal oceans and lakes.
food chain (p. 616) The circuit along which energy flows from producers (plants), which
manufacture their own food, to consumers (animals); a one-directional flow of chemical energy,
ending with decomposers.
food web (p. 616) A complex network of interconnected food chains. (See Food chain.)
detritivore (p. 617) Detritus feeder and decomposer that consumes, digests, and destroys
organic wastes and debris. Detritus feeders— worms, mites, termites, centipedes, snails, crabs,
and even vultures, among others—consume detritus and excrete nutrients and simple inorganic
compounds that fuel an ecosystem. (Compare Decomposers.)
decomposer (p. 617) Bacteria and fungi that digest organic debris outside their bodies and
absorb and release nutrients in an ecosystem. (See Detritivore.)
herbivore (p. 617) The primary consumer in a food web, which eats plant material formed by a
producer (plant) that has photosynthesized organic molecules. (Compare Carnivore.)
carnivore (p. 617) A secondary consumer that principally eats meat for sustenance. The top
carnivore in a food chain is considered a tertiary consumer. (Compare Herbivore.)
omnivore (p. 617) A consumer that feeds on both producers (plants) and consumers (meat)—a
role occupied by humans, among other animals. (Compare Consumer, Producer.)
community (p. 619) A convenient biotic subdivision within an ecosystem; formed by interacting
populations of animals and plants in an area.
habitat (p. 619) A physical location to which an organism is biologically suited. Most species
have specific habitat parameters and limits.
ecological niche (p. 619) The function, or operation, of a life form within a given ecological
community.
life zone (p. 621) A zonation by altitude of plants and animals that form distinctive communities.
Each life zone possesses its own temperature and precipitation relations.
limiting factor (p. 622) The physical or chemical factor that most inhibits biotic processes,
through either lack or excess.
fire ecology (p. 623) The study of fire as a natural agent and dynamic factor in community
succession.
ecological succession (p. 623) The process whereby different and usually more complex
assemblages of plants and animals replace older and usually simpler communities; communities
are in a constant state of change as each species adapts to changing conditions. Ecosystems
do not exhibit a stable point or successional climax condition as previously thought. (See
Primary succession, Secondary succession.)
primary succession (p. 624) Succession that occurs among plant species in an area of new
surfaces created by mass movement of land, cooled lava flows and volcanic eruption
landscapes, or surface mining and clear-cut logging scars; exposed by retreating glaciers, or
made up of sand dunes, with no trace of a former community.
pioneer community (p. 624) The initial plant community in an area; usually is found on new
surfaces or those that have been stripped of life, as in beginning primary succession, and
includes lichens, mosses, and ferns growing on bare rock.
secondary succession (p. 624) Succession that occurs among plant species in an area where
vestiges of a previously functioning community are present; an area where the natural
community has been destroyed or disturbed, but where the underlying soil remains intact.
eutrophication (p. 626) The gradual enrichment of water bodies that occurs with nutrient inputs,
either natural or human-caused.
biodiversity (p. 628) A principle of ecology and biogeography: The more diverse the species
population in an ecosystem (in number of species, quantity of members in each species, and
genetic content), the more risk is spread over the entire community, which results in greater
overall stability, greater productivity, and increased use of nutrients, as compared to a
monoculture of little or no diversity.
evolution (p. 628) A theory that single-cell organisms adapted, modified, and passed along
inherited changes to multicellular organisms. The genetic makeup of successive generations is
shaped by environmental factors, physiological functions, and behaviours that created a greater
rate of survival and reproduction and were passed along through natural selection.
Chapter 20
biogeographic realm (p. 642) One of eight regions of the biosphere, each representative of
evolutionary core areas of related flora (plants) and fauna (animals); a broad geographical
classification scheme.
biome (p. 643) A large-scale, stable, terrestrial or aquatic ecosystem classified according to the
predominant vegetation type and the adaptations of particular organisms to that environment.
ecotone (p. 644) A boundary transition zone between adjoining ecosystems that may vary in
width and represent areas of tension as similar species of plants and animals compete for the
resources. (See Ecosystem.)
invasive species (p. 646) Species that are brought, or introduced, from elsewhere by humans,
either accidentally or intentionally. These non-native species are also known as exotic species
or alien species.
tropical rain forest (p. 647) A lush biome of tall broadleaf evergreen trees and diverse plants and
animals, roughly between 23.5° N and 23.5° S. The dense canopy of leaves is usually arranged
in three levels.
tropical seasonal forest and scrub (p. 651) A variable biome on the margins of the rain forests,
occupying regions of lesser and more erratic rainfall; the site of transitional communities
between the rain forests and tropical grasslands.
tropical savanna (p. 651) A major biome containing large expanses of grassland interrupted by
trees and shrubs; a transitional area between the humid rain forests and tropical seasonal
forests and the drier, semiarid tropical steppes and deserts.
midlatitude broadleaf and mixed forest (p. 654) mixed forest (20) A biome in moist continental
climates in areas of warm-to-hot summers and cool-to-cold winters; relatively lush stands of
broadleaf forests trend northward into needleleaf evergreen stands.
boreal forest (p. 655) See Needleleaf forest.
needleleaf forest (p. 655) Consists of pine, spruce, fir, and larch and stretches from the east
coast of Canada westward to Alaska and continuing from Siberia westward across the entire
extent of Russia to the European Plain; called the taiga (a Russian word) or the boreal forest;
principally in the microthermal climates. Includes montane forests that may be at lower latitudes
at higher elevations.
taiga (p. 655) See Needleleaf forest.
montane forest (p. 655) Needleleaf forest associated with mountain elevations. (See Needleleaf
forest.)
temperate rain forest (p. 657) A major biome of lush forests at middle and high latitudes; occurs
along narrow margins of the Pacific Northwest in North America, among other locations;
includes the tallest trees in the world.
Mediterranean shrubland (p. 658) A major biome dominated by the Mediterranean (dry summer)
climate and characterised by sclerophyllous scrub and short, stunted, tough forests. (See
Chaparral.)
chaparral (p. 658) Dominant shrub formations of Mediterranean (dry summer) climates;
characterised by sclerophyllous scrub and short, stunted, tough forests; derived from the
Spanish chaparro; specific to California. (See Mediterranean shrubland.)
midlatitude grassland (p. 659) The major biome most modified by human activity; so named
because of the predominance of grasslike plants, although deciduous broadleafs appear along
streams and other limited sites; location of the world’s breadbaskets of grain and livestock
production.
warm desert and semidesert (p. 659) A desert biome caused by the presence of subtropical
high-pressure cells; characterised by dry air and low precipitation.
cold desert and semidesert (p. 659) A type of desert biome found at higher latitudes than warm
deserts. Interior location and rain shadows produce these cold deserts in North America.
polar desert (p. 659) A type of desert biome found at higher latitudes than cold deserts,
occurring mainly in the very cold, dry climates of Greenland and Antartica.
arctic tundra (p. 661) A biome in the northernmost portions of North America and northern
Europe and Russia, featuring low, ground-level herbaceous plants as well as some woody
plants. (See Alpine tundra.)
alpine tundra (p. 661) Tundra conditions at high elevation. (See Arctic tundra.)
island biogeography (p. 664) Island communities are special places for study because of their
spatial isolation and the relatively small number of species present. Islands resemble natural
experiments because the impact of individual factors, such as civilization, can be more easily
assessed on islands than over larger continental areas.
large marine ecosystem (LME) (p. 664) Distinctive oceanic regions identified for conservation
purposes on the basis of organisms, ocean-floor topography, currents, areas of nutrient- rich
upwelling circulation, or areas of significant predation, including human. The LME system is
managed by the U.S. National Oceanic and Atmospheric Administration (NOAA).
anthropogenic biome (p. 665) A recent conceptual term for large-scale, stable ecosystems that
result from ongoing human interaction with natural environments. Human modifications are
often linked to land-use practices such as agriculture, forestry, and urbanization.