Environmental Problems, Their Causes, and Sustainability 1

eutrophication Physical, chemical, andbiological changes that take place after alake, estuary, or slow-flowing streamreceives inputs of plant nutrients—mostlynitrates and phosphates—from natural erosionand runoff from the surrounding landbasin. See cultural eutrophication.eutrophic lake Lake with a large or excessivesupply of plant nutrients, mostlynitrates and phosphates. Comparemesotrophic lake, oligotrophic lake.evaporation Conversion of a liquid into agas.even-aged management Method of forestmanagement in which trees, sometimes of asingle species in a given stand, are maintainedat about the same age and size andare harvested all at once. Compare unevenagedmanagement.evergreen plants Plants that keep some oftheir leaves or needles throughout the year.Examples are ferns and cone-bearing trees(conifers) such as firs, spruces, pines, redwoods,and sequoias. Compare deciduousplants, succulent plants.evolution See biological evolution.exhaustible resource See nonrenewableresource.existence value See intrinsic value.exotic species See nonnative species.experiment Procedure a scientist uses tostudy some phenomenon under knownconditions. Scientists conduct some experimentsin the laboratory and others innature. The resulting scientific data or factsmust be verified or confirmed by repeatedobservations and measurements, ideally byseveral different investigators.exploitation competition Situation inwhich two competing species have equalaccess to a specific resource but differ inhow quickly or efficiently they exploit it.See interference competition, interspecificcompetition.exponential growth Growth in whichsome quantity, such as population size oreconomic output, increases at a constantrate per unit of time (such as 2% per year).An example is the growth sequence 2, 4, 8,16, 32, 64 and so on; when the increase inquantity over time is plotted, this type ofgrowth yields a curve shaped like the letterJ. Compare linear growth.external benefit Beneficial socialeffect of producing and using an economicgood that is not included in the marketprice of the good. Compare external cost,full cost.external cost Harmful social effect of producingand using an economic good that isnot included in the market price of thegood. Compare external benefit, full cost,internal cost.externalities Social benefits (“goods”) andsocial costs (“bads”) not included in themarket price of an economic good. Seeexternal benefit, external cost. Compare fullcost, internal cost.extinction Complete disappearance of aspecies from the earth. This happens whena species cannot adapt and successfullyreproduce under new environmental conditionsor when it evolves into one or morenew species. Compare speciation. See alsoendangered species, mass depletion, mass extinction,threatened species.family planning Providing information,clinical services, and contraceptives to helppeople choose the number and spacing ofchildren they want to have.famine Widespread malnutrition andstarvation in a particular area because of ashortage of food, usually caused bydrought, war, flood, earthquake, or othercatastrophic events that disrupt food productionand distribution.feedback loop Circuit of sensing, evaluating,and reacting to changes in environmentalconditions as a result of information fedback into a system; it occurs when onechange leads to some other change, whicheventually reinforces or slows the originalchange. See negative feedback loop, positivefeedback loop.feedlot Confined outdoor or indoor spaceused to raise hundreds to thousands ofdomesticated livestock. Compare rangeland.fermentation See anaerobic respiration.fertility The number of births that occurto an individual woman or in a population.fertilizer Substance that adds inorganic ororganic plant nutrients to soil and improvesits ability to grow crops, trees, or other vegetation.See commercial inorganic fertilizer,organic fertilizer.first law of thermodynamics In anyphysical or chemical change, no detectableamount of energy is created or destroyed,but in these processes energy can bechanged from one form to another; you cannotget more energy out of something thanyou put in; in terms of energy quantity, youcannot get something for nothing (there isno free lunch). This law does not apply tonuclear changes, in which energy can beproduced from small amounts of matter.See second law of thermodynamics.fishery Concentrations of particularaquatic species suitable for commercial harvestingin a given ocean area or inland bodyof water.fish farming Form of aquaculture inwhich fish are cultivated in a controlledpond or other environment and harvestedwhen they reach the desired size. See alsofish ranching.fish ranching Form of aquaculture inwhich members of a fish species such assalmon are held in captivity for the first fewyears of their lives, released, and then harvestedas adults when they return from theocean to their freshwater birthplace tospawn. See also fish farming.fissionable isotope Isotope that cansplit apart when hit by a neutron at theright speed and thus undergo nuclearfission. Examples are uranium-235 andplutonium-239.floodplain Flat valley floor next to astream channel. For legal purposes, theterm often applies to any low area that hasthe potential for flooding, including certaincoastal areas.flows See throughputs.flyway Generally fixed route along whichwaterfowl migrate from one area to anotherat certain seasons of the year.food chain Series of organisms in whicheach eats or decomposes the preceding one.Compare food web.food web Complex network of manyinterconnected food chains and feedingrelationships. Compare food chain.forest Biome with enough average annualprecipitation (at least 76 centimeters, or 30inches) to support growth of various treespecies and smaller forms of vegetation.Compare desert, grassland.fossil fuel Products of partial or completedecomposition of plants and animals thatoccur as crude oil, coal, natural gas, orheavy oils as a result of exposure to heatand pressure in the earth’s crust over millionsof years. See coal, crude oil, naturalgas.fossils Skeletons, bones, shells, bodyparts, leaves, seeds, or impressions of suchitems that provide recognizable evidence oforganisms that lived long ago.free-access resource See common-propertyresource.freons See chlorofluorocarbons.freshwater life zones Aquatic systemswhere water with a dissolved salt concentrationof less than 1% by volume accumulateson or flows through the surfaces ofterrestrial biomes. Examples are standing(lentic) bodies of freshwater such as lakes,ponds, and inland wetlands and flowing(lotic) systems such as streams and rivers.Compare biome.front The boundary between two airmasses with different temperatures anddensities. See cold front, warm front.frontier worldview Viewing undevelopedland as a hostile wilderness to be conquered(cleared, planted) and exploited for itsresources as quickly as possible. Compareenvironmental wisdom worldview, planetarymanagement worldview, spaceship-earth worldview,stewardship worldview.frontier forest See old-growth forest.frontier science Preliminary scientificdata, hypotheses, and models that have notbeen widely tested and accepted. Comparejunk science, sound science.full cost Cost of a good when its internalcosts and its estimated short- and long-termexternal costs are included in its marketprice. Compare external cost, internal cost.functional diversity Biological and chemicalprocesses or functions such as energyflow and matter cycling needed for the survivalof species and biological communities.See biodiversity, ecological diversity, geneticdiversity, species diversity.GLOSSARYG7