Glossary - Agroecology: The Ecology of Sustainable Food Systems - page 370

clone An individual produced asexually from the tissues,
cells, or genome of another individual. A clone is genet-
ically identical to the individual from which it was
derived.
cold air drainage The flow of cold air down a slope at
night, when reradiation of heat (and therefore cooling of
air) occurs more rapidly at higher elevations.
colluvium Soil that has been transported to its present
location by the actions of gravity.
commensalism An interorganism interaction in which
one organism is aided by the interaction and the other is
neither benefited nor harmed.
community All the organisms living together in a
particular location.
compensating factor A factor of the environment that
overcomes, eliminates, or modifies the impact of
another factor.
competition An interaction in which two organisms
remove from the environment a limited resource that
both require, and both organisms are harmed in the pro-
cess. Competition can occur between members of the
same species and between members of different species.
consumer Ecologically, an organism that ingests other
organisms (or their parts or products) to obtain its food
energy. Agroecologically, a person who obtains food or
food products from a farmer for his or her sustenance.
continental influence The climatic effect of being dis-
tant from the moderating effects of a large body of water.
Coriolis effect The deflection of air currents in atmo-
spheric circulation cells due to the rotation of the earth.
cross-pollination The fertilization of a flower by pollen
from the flower of another individual of the same
species.
CSA Community-supported agriculture . A subscrip-
tion arrangement in which a farm regularly delivers its
products to a central pickup point, or directly to the
consumer.
cultural energy inputs Forms of energy used in agricul-
tural production that come from sources controlled or
provided by humans.
cytosterility A genetically controlled condition of male
sterility in the breeding line of a self-pollinating crop
variety. A breeding line with cytosterility is used as the
seed-producing parental line in the production of hybrid
seed.
dark reactions The processes of photosynthesis that do
not require light; specifically, the carbon-fixing and
sugar-synthesizing processes of the Calvin cycle.
decomposer A fungal or bacterial organism that obtains
its nutrients and food energy by breaking down dead
organic and fecal matter and absorbing some of its
nutrient content.
density-dependent Directly linked to population den-
sity. This term is usually used to describe growth-limit-
ing feedback mechanisms in a population of organisms.

density-independent Not directly linked to population
density. This term is usually used to describe growth-
limiting feedback mechanisms in a population
of organisms.
detritivore An organism that feeds on dead organic and
fecal matter.
dew point The temperature at which relative humidity
reaches 100% and water vapor is able to condense into
water droplets. The dew point varies depending on the
absolute water vapor content of the air.
directed selection The process of controlling genetic
change in domesticated plants through manipulation of
the plants' environment and their breeding process.
disturbance An event or short-term process that alters
a community or ecosystem by changing the relative
population levels of at least some of the component
species.
diversity (1) The number or variety of species in a loca-
tion, community, ecosystem, or agroecosystem. (2) The
degree of heterogeneity of the biotic components of an
ecosystem or agroecosystem (see ecological diversity ).
domestication The process of altering, through directed
selection, the genetic makeup of a species so as to
increase the species' usefulness to humans.
dominant species The species with the greatest impact
on both the biotic and abiotic components of
its community.
dry farming The practice of conserving natural rainfall
so as to facilitate farming without irrigation in a normally
dry environment or season.
dynamic equilibrium A condition characterized by an
overall balance in the processes of change in an ecosys-
tem, made possible by the system's resiliency, and result-
ing in relative stability of structure and function despite
constant change and small-scale disturbance.
easily available water That portion of water held in the
soil that can be readily absorbed by plant roots—usually
capillary water between 0.3 and 15 bars of suction.
ecological diversity The degree of heterogeneity of an
ecosystem's or agroecosystem's species makeup, genetic
potential, vertical spatial structure, horizontal spatial
structure, trophic structure, ecological functioning, and
change over time.
ecological energy inputs Forms of energy used in agri-
cultural production that come directly from the sun.
ecological niche An organism's place and function in
the environment, defined by its utilization of resources.
ecosystem A functional system of complementary rela-
tions between living organisms and their environment
within a certain physical area.
ecosystem services The processes by which the environ-
ment produces essential resources, such as clean water
and air, that we often take for granted.
ecotone A zone of gradual transition between two dis-
tinct ecosystems, communities, or habitats.