Botkin Environmental Science Earth as Living Planet 8th txtbk

G-6 Glossary
ing fossil fuels is such a public benefit and an argument for
maintaining large areas of forests.
Ecological niche The general concept is that the niche is a species’
“profession”—what it does to make a living. The term is
also used to refer to a set of environmental conditions within
which a species is able to persist.
Ecological succession The process of the development of an
ecological community or ecosystem, usually viewed as a
series of stages—early, middle, late, mature (or climax), and
sometimes postclimax. Primary succession is an original
establishment; secondary succession is a reestablishment.
Ecology The science of the study of the relationships between
living things and their environment.
Ecosystem An ecological community and its local, nonbiological
community. An ecosystem is the minimum system
that includes and sustains life. It must include at least an
autotroph, a decomposer, a liquid medium, a source and
sink of energy, and all the chemical elements required by
the autotroph and the decomposer.
Ecosystem effect Effects that result from interactions among
different species, effects of species on chemical elements
in their environment, and conditions of the environment.
Ecosystem energy flow The flow of energy through an
ecosystem—from the external environment through a series
of organisms and back to the external environment.
Ecotopia A society based on sustainable development and
sound environmental planning characterized by a stable
human population within the carrying capacity of earth. It
is thought of as an ideal state.
Ecotourism Tourism based on an interest in observing of
nature.
ED-50 The effective dose, or dose that causes an effect in
50% of the population on exposure to a particular toxicant.
It is related to the onset of specific symptoms, such as loss
of hearing, nausea, or slurred speech.
Edge effect An effect that occurs following the forming of an
ecological island; in the early phases the species diversity
along the edge is greater than in the interior. Species escape
from the cut area and seek refuge in the border of the forest,
where some may last only a short time.
Efficiency The primary definition used in the text is the
ratio of output to input. With machines, usually the ratio
of work or power produced to the energy or power used to
operate or fuel them. With living things, efficiency may be
defined as either the useful work done or the energy stored
in a useful form compared with the energy taken in.
Efficiency improvements With respect to energy, refers to
designing equipment that will yield more energy output
from a given amount of energy input.
Effluent Any material that flows outward from something.
Examples include wastewater from hydroelectric plants
and water discharged into streams from waste-disposal
sites.
Effluent stream Type of stream where flow is maintained
during the dry season by groundwater seepage into the
channel.
El Niño Natural perturbation of the physical earth system
that affects global climate. Characterized by development
of warm oceanic waters in the eastern part of the tropical
Pacific Ocean, a weakening or reversal of the trade winds,
and a weakening or even reversal of the equatorial ocean
currents. Reoccurs periodically and affects the atmosphere
and global temperature by pumping heat into the
atmosphere.
Electromagnetic fields (EMFs) Magnetic and electrical
fields produced naturally by our planet and also by appliances
such as toasters, electric blankets, and computers.
There currently is controversy concerning potential adverse
health effects related to exposure to EMFs in the workplace
and home from such artificial sources as power lines and
appliances.
Electromagnetic spectrum All the possible wavelengths of
electromagnetic energy, considered as a continuous range.
The spectrum includes long wavelength (used in radio
transmission), infrared, visible, ultraviolet, X rays, and
gamma rays.
Endangered species A species that faces threats that might
lead to its extinction in a short time.
Endemic species A species that has evolved in, and lives only
within, a specific location. e.g. the California condor is endemic
to the Pacific coast of North America.
Energy An abstract concept referring to the ability or capacity
to do work.
Energy efficiency Refers to both first-law efficiency and
second-law efficiency, where first-law efficiency is the ratio
of the actual amount of energy delivered to the amount
of energy supplied to meet a particular need, and secondlaw
efficiency is the ratio of the maximum available work
needed to perform a particular task to the actual work used
to perform that task.
Energy flow The movement of energy through an ecosystem
from the external environment through a series of organisms
and back to the external environment. It is one of the fundamental
processes common to all ecosystems.
Entropy A measure in a system of the amount of energy that
is unavailable for useful work. As the disorder of a system
increases, the entropy in a system also increases.
Environment All factors (living and nonliving) that actually
affect an individual organism or population at any point
in the life cycle. Environment is also sometimes used to
denote a certain set of circumstances surrounding a particular
occurrence (environments of deposition, for example).
Environmental audit A process of determining the past
history of a particular site, with special reference to the
existence of toxic materials or waste.
Environmental economics Economic effects of the environment
and how economic processes affect that environment,
including its living resources.
Environmental ethics A school, or theory, in philosophy that
deals with the ethical value of the environment.
Environmental geology The application of geologic information
to environmental problems.
Environmental impact The effects of some action on the
environment, particularly action by human beings.
Environmental impact report (EIR) Similar to the environmental
impact statement, a report describing potential