Glossary - Agroecology: The Ecology of Sustainable Food Systems - page 371

ecotype A population of a species that differs genetically
from other populations of the same species because local
conditions have selected for certain unique physiological
or morphological characteristics.
edge effect The phenomenon of an edge community, or
ecotone, having greater ecological diversity than the
neighboring communities.
emergent property A characteristic of a system that
derives from the interaction of its parts and is not observ-
able or inherent in the parts considered separately.
environmental complex The composite of all the indi-
vidual factors of the environment acting and interacting
in concert.
environmental resistance The genetically based ability
of an organism to withstand stresses, threats, or limiting
factors in the environment.
eolian soil Soil that has been transported to its current
location by the actions of wind ( aeolian is an acceptable
alternative spelling).
epiphyll A plant that uses the leaf of another plant for
support, but that draws no nutrients from the host plant.
epiphyte A plant that uses the trunk or stem of another
plant for support, but that draws no nutrients from the
host plant.
eutrophication Nutrient enrichment of water that leads to
algal blooms, disruption of food webs, and in the worst
cases, complete eradication of life through deoxygenation.
evapotranspiration All forms of evaporation of liquid
water from the earth's surface, including the evapora-
tion of bodies of water and soil moisture and the
evaporation from leaf surfaces that occurs as part of
transpiration.
externalized cost In economic terms, a negative conse-
quence that is put outside (made external to) the system
being considered. Conventional agriculture has many
externalized costs, including degradation of ecological
resources, hazards to human health, and disintegration
of social systems. Every externalized cost involves
privatizing a gain and socializing its associated costs.
field capacity The amount of water the soil can hold
once gravitational water has drained away; this water is
mostly capillary water held to soil particles with at least
0.3 bars of suction.
food citizen a consumer who makes food decisions that
support a democratic, economically just, and environ-
mentally sustainable food system.
food democracy a food system in which consumers are
empowered to make informed choices and farmers can
make a living using sustainable practices.
food security Access to sufficient food of appropriate
diversity for a healthy diet.
foodshed a geographically limited sphere of land, peo-
ple, and businesses tied together by food relationships.
food system The interconnected meta-system of agroeco-
systems, their economic, social, cultural, and technological

support systems, and systems of food distribution and
consumption.
generalist A species that tolerates a broad range of envi-
ronmental conditions; a generalist has a broad ecological
niche.
genetic engineering Transfer, by biotechnological
methods, of genetic material from one organism to
another. See transgenic .
genetic erosion The loss of genetic diversity in domes-
ticated organisms that has resulted from human reliance
on a few genetically uniform varieties of food crop plants
and animals.
genetic vulnerability The susceptibility of genetically
uniform crops to damage or destruction caused by out-
breaks of a disease or pest or unusually poor weather
conditions or climatic change.
genotype An organism's genetic information, consid-
ered as a whole.
GEO A genetically engineered organism.
glacial soil Soil that has been transported to its current
location by the movement of glaciers.
gravitational water That portion of water in the soil not
held strongly enough by adhesion to soil particles to
resist the downward pull of gravity.
green manure Organic matter added to the soil when a
cover crop (often leguminous) is tilled in.
gross primary productivity The rate of conversion of
solar energy into biomass in an ecosystem.
habitat The particular environment, characterized by a
specific set of environmental conditions, in which a
given species occurs.
hardening Subjecting a seedling or plant to cooler tem-
peratures in order to increase its resistance to more
extreme cold.
herbivore An animal that feeds exclusively or mainly
on plants. Herbivores convert plant biomass into animal
biomass.
heterosis The production of an exceptionally vigorous
and/or productive hybrid progeny from a directed cross
between two pure-breeding plant lines.
heterotroph An organism that consumes other organ-
isms to meet its energy needs.
horizons Visually distinguishable layers in the soil profile.
horizontal resistance The ability of a crop variety to
resist generally the threats posed by all possible diseases,
pests, and environmental changes, based on the variety's
possession of a variety of resistant traits accumulated
through population-level breeding and ongoing directed
selection at all levels. Contrasted to vertical resistance ,
the ability of a variety to resist a specific pathogen or pest.
humification The decomposition or metabolization of
organic material in the soil.
humus The fraction of organic matter in the soil result-
ing from decomposition and mineralization of organic
material.