Glossary - Agroecology: The Ecology of Sustainable Food Systems - page 369

Glossary

abiotic factor A nonliving component of the environ-
ment, such as soil, nutrients, light, fire, or moisture.
adaptation (1) Any aspect of an organism or its parts that
is of value in allowing the organism to withstand the
conditions of the environment. (2) The evolutionary
process by which a species' genome and phenotypic
characteristics change over time in response to changes
in the environment.
agrobiodiversity The component of biodiversity related
to food and agriculture production. The term encom-
passes diversity within species, among species, within
agroecosystems, within regions, and in the world food
system as a whole.
agroecology The science of applying ecological concepts
and principles to the design and management of sustain-
able food systems.
agroecosystem An agricultural system understood as an
ecosystem.
agroforestry The practice of including trees in crop- or
animal-production agroecosystems.
agrosilvopastoral system An agroecosystem combining
trees, livestock grazing, and crops.
allelopathy An interference interaction in which a plant
releases into the environment a compound that inhibits
or stimulates the growth or development of other plants.
alluvium Soil that has been transported to its present
location by water flow.
alpha diversity The variety of species in a particular
location in one community or agroecosystem.
alternative food network A business, program, or insti-
tution that promotes a more sustainable relationship
between the growing of food and its consumption.
amensalism An interorganism interaction in which one
organism negatively impacts another organism without
receiving any direct benefit itself.
animal husbandry The practice of breeding and
caring for livestock animals such as goats, cattle,
sheep, camels, etc.
autotroph An organism that satisfies its need for organic
food molecules by using the energy of the sun, or of the
oxidation of inorganic substances, to convert inorganic
molecules into organic molecules.
beta diversity The difference in the assemblage of species
from one location or habitat to another nearby location or
habitat, or from one part of an agroecosystem to another.
biogeochemical cycle The manner in which the atoms
of an element critical to life (such as carbon, nitrogen,
or phosphorus) move from the bodies of living organisms
to the physical environment and back again.

biological control The use of natural enemies for the
control of pests.
biomass The mass of all the organic matter in a given
system at a given point in time.
bioregionalism Integration of human activities within
the ecological limits of a landscape.
biotic factor An aspect of the environment related to
organisms or their interactions.
boundary layer A layer of air saturated with water
vapor (from transpiration) that forms next to a leaf
surface when there is no air movement.
buffer zone A less-intensively managed and less-
disturbed area at the margins of an agroecosystem
that protects the adjacent natural system from the
potential negative impacts of agricultural activities
and management.
bulk density The mass of soil per unit of volume.
capillary water The water that fills the micropores of
the soil and is held to soil particles with a force between
0.3 and 31 bars of suction. Much of this water (that
portion held to particles with less than 15 bars of suction)
is readily available to plant roots.
carbon dioxide compensation point The concentra-
tion of carbon dioxide in a plant's chloroplasts below
which the amount of photosynthate produced fails to
compensate for the amount of amount of photosynthate
used in respiration.
carbon fixation The part of the photosynthetic process
in which carbon atoms are extracted from atmospheric
carbon dioxide and used to make simple organic com-
pounds that eventually become glucose.
carbon partitioning The manner in which a plant
allocates to different plant parts the photosynthate it
produces.
carbon sequestration Capturing or locking up of car-
bon dioxide from the atmosphere in terrestrial or marine
sinks (eg. soil, trees, animals, microorganisms).
catabatic warming The process that occurs when a
large air mass expands after having been forced over
a mountain range and becomes warmer and dryer as a
result of the expansion.
cation exchange capacity A measurement of a soil's
ability to bind positively charged ions (cations), which
include many important nutrients.
climax In classical ecological theory, the end point of
the successional process; today, we refer instead to the
stage of maturity reached when successional develop-
ment shifts to dynamic change around an equilibrium
point.

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