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Exam 3

Terms in this set (99)

Aquaculture
farming of fish and other aquatic animals, either in ocean-based enclosures or in land-based ponds.
Bt gene
gene which originally came from Bacillus thuringiensis, and has been transplanted into corn, potatoes, cotton, and other crops to make them resistant to butterflies and beetles.
Bycatch
organisms that are accidentally captured and killed during fishing operations.
Chronic undernourishment
condition of people who receive less than the recommended 2200 calories per day (over 850 million people worldwide).
Confined animal feeding operation (CAFO)
also called a feedlot, a facility where animals are enclosed in giant enclosures and receive special mixtures of food to maximize their growth rates.
Conservation Reserve Program (CRP)
U.S. government program which pays farmers to take highly erodible land out of production.
Famine
a widespread scarcity of food; a large-scale food shortage.
Genetically modified organism (GMO)
plants that have been modified by the addition of genes taken from other species that allow the plants to survive in less than optimum conditions, be more resistant to pests or disease, or to contain more nutrients than their wild relatives.
Green Revolution
a dramatic increase in the efficiency of food production, beginning in the middle of the last century, caused in large degree by the efforts of agricultural research stations.
High responder
type of crop which produces a great deal of edible product, but requires optimum amounts of fertilizer, water, and pesticides.
Market failure
a situation in which prices paid by consumers do not reflect the true costs involved with production, specifically environmental costs.
Obesity
a condition in which excess body fat has accumulated to the point that it is unhealthy; often considered to occur when a person is more than 20% over the ideal body weight.
Polyculture
aquaculture which includes mixed-species assortments of various feeding types.
Roundup Ready crops
crops which have been genetically modified to tolerate high levels of the herbicide Roundup.
Subsidy
money paid to farmers or manufacturers to keep prices below what they would be in a competitive market.
Alfasol
organic-rich, deciduous forest soil, excellent for agriculture, but usually not as thick as mollisols.
A horizon
surface soil or topsoil, where most crops are rooted.
Arable
describes land which is well-suited for agriculture.
Aridisol
desert soils, often rich in salts.
Bedrock
solid rock substrate below soil.
B horizon
subsoil, often rich in clays, below most organic activity.
Biocide
pesticide which kills a wide range of living things.
Biological control
use of living organisms or toxins derived from them in place of synthetic chemical pesticides.
Chlorinated hydrocarbon (organochlorine)
class of pesticides made of organic molecules with at least one active chlorine atom, which are persistent and highly toxic. Examples include Atrazine, DDT, chlordane, Aldrin, dieldrin, toxaphene, and 2,4-D.
C horizon
layer of soil below the B horizon consisting of small rock fragments.
Clay
soil component made of small mineral particles which are sticky and hold water.
Conserve-till
reduced tillage system which uses a coulter (a tool like a giant pizza cutter) to place seeds into the ground.
Contour farming
planting along the contours of hills and other topography to reduce soil erosion.
Crop rotation
method of soil and land conservation in which a series of different crops is grown on the same land in different seasons or years.
Desertification
conversion of productive land to desert because of erosion or overuse.
E horizon
washed-out layer which sometimes occurs between the A horizon and B horizon; clays in this layer have been washed down to the B horizon.
Fertilizer
material of natural or synthetic origin which is applied to agricultural fields to provide minerals or other nutrients for plant growth.
Fumigant
small molecules such as carbon tetrachloride, ethylene dibromide, and methylene bromide, which can be delivered in the form of a gas, and are used to control fungus and to prevent decay and insect and rodent infestations.
Fungicide
pesticide which kills fungi.
Grasshopper effect
situation in which contaminants evaporate from water and soil in warm areas and precipitate out in colder regions, leading to bioaccumulation and biomagnification.
Gully erosion
type of erosion in which rills cannot be smoothed over by normal tillage.
Herbicide
pesticide which kills plants.
Hypochlorite (bleach)
refers to sodium hypochlorite, widely used to purify water.
Inorganic pesticide
compounds of toxic elements such as arsenic, sulfur, copper and mercury, which are used as broad-spectrum pesticides. They are highly toxic and nearly indestructible.
Insecticide
pesticide which kills insects.
Integrated pest management
flexible, ecologically based strategy that uses mechanical cultivation and vacuuming bugs off crops as an alternative to chemicals, but uses chemicals when absolutely necessary.
Loam
soils with a mixture of sand, silt, and clay which are good for growing crops and also resistant to erosion.
Locavore
person who tries to reduce the impact of agriculture by using as much locally grown, seasonal food as possible.
Mollisol
organic-rich, black grassland soil, excellent for agriculture.
Mychorrhizae
portions of fungus which grow in symbiosis with plants and provide extra surface area for absorption of water and nutrients, and which are provided organic material by the plant.
No-till
reduced tillage system which uses a drill-like tool to place seeds into the ground.
O horizon
top layer of soil, consisting of leaf litter and plant debris, where most soil fauna live.
Organic agriculture
agriculture which involves little or no use of pesticides.
Organophosphate
class of chemicals, often esters of phosphoric acid, which are used as herbicides. Examples include Roundup, parathion, and malathion.
Perennial plants
plants that grow for more than two years, such as coffee or tea.
Pesticide
general term for any chemical that kills pests.
Pest resurgence
regrowth of pest populations due to evolutionary change leading to resistance to pesticides.
Polyculture
growth of several crop plants together to reduce the opportunity for growth of large pest populations.
POP (Persistent organic pollutant)
substances which last for many years in the environment and are especially subject to bioaccumulation and biomagnification; examples include PCBs, PBDEs, PVCs, perchlorates, and BPA.
Pyrethrum
natural organic pesticide extracted from a Chrysanthemum plant, used to kill insects or prevent wood decay.
Reduced tillage
farming techniques which disturb the soil as little as possible, to expose less soil to erosion.
Rill erosion
type of erosion in which running water cuts small channels in the soil.
Sheet erosion
type of erosion in which a thin layer of soil is taken off the land.
Silt
soil component made of mineral particles which are smaller than sand but larger than clay.
Soil
mixture of organic and inorganic material, water, and air which lies on top of the ground and forms the substrate for terrestrial ecosystems.
Strip farming
planting alternating crops with each other to reduce erosion and pest populations.
Terracing
shaping the land to hold water and soil.
Topsoil
surface soil where plants are rooted, also referred to as the A horizon.
Alien species
organisms moved into previously unoccupied habitat by humans.
Allopatric
type of speciation which may occur when a single population is divided into two populations by a geographic barrier.
Background extinction
continuous low-level rate of natural extinction (estimated to be one species every four years).
Biodiversity
the number and variety of living organisms in a given area.
Black market
trade in illegal items such as endangered wildlife or products made from endangered species.
Captive breeding program
program in which endangered or threatened animals are bred under safe, controlled conditions usually with the eventual goal of reintroduction into the wild.
Convention on International Trade in Endangered Species (CITES)
international treaty which regulates the international trade in endangered species and the products made from them.
Diffuse chemical coevolution
property of evolution in which natural selection favors individuals that accumulate compounds effective against a wide variety of enemies.
Dispersal
the ability of organisms to reach new environments.
Ecosystem diversity
the variety of ecosystems on earth.
Ecotourism
tourism which contributes to the conservation of natural environments in such a way that it contributes to the well-being of local communities.
Edge effect
threat to biodiversity caused by increased amounts of habitat edges due to habitat fragmentation, caused by increased vulnerability of inhabitants of the habitat to predation, stronger winds, temperature changes, and increased fire incidence.
Endangered
a species which has been determined to face extinction or extirpation without action to save it.
Endangered Species Act (1973)
law enacted in the United States which protects endangered and threatened species.
Endemic
refers to species that are found only in a specific place.
Enemy release hypothesis
hypothesis that states that the population of an alien species can grow rapidly because its predators, parasites, and pathogens were not moved with the species.
Ethnobotany
study of how indigenous cultures use plants as medicines.
Evenness
distribution of individuals among species in an area.
Extinction
complete loss of a species.
Fragmentation
break-up of continuous habitat into smaller areas.
Genetic diversity
the variety of alleles and genes in the DNA of organisms.
Habitat conversion
change in land quality as natural habitats are converted to agricultural, urban, or other human uses.
Immigration
movement of individuals or new species into an area.
Insurance
a method of reducing risk by spreading the potential effects of the risk.
Invasive species
an alien species which displaces indigenous species or becomes established in places where it was previously uncommon.
Keystone species
species whose presence and numbers control the integrity of a community or ecosystem and allow that system to persist within its natural range of environmental conditions.
Mass extinction
periods in the earth's history when the extinction rate was much greater than the background extinction rate, and a large portions of the earth's biodiversity disappeared in a short period of time.
Passenger species (redundant species)
species which is not as critical as a keystone species; its loss has smaller effects on an ecosystem.
Poaching
illegal collecting of animals or plants.
Sixth extinction
current extinction event caused by human activity.
Speciation
evolution of new species from existing species.
Species-area relationship
idea put forth by MacArthur and Wilson which says that the larger an area is, the more species that are likely to occur there.
Species diversity
the total number of species living in a specified area; same thing as species richness.
Species richness
the total number of species present in an area.
Sympatric
type of speciation which occurs without division of a population into two populations by a geographic barrier.
Threatened
term which is used to refer to animals or plants protected under the Endangered Species Act because they are likely to become endangered without action to protect them.
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