Environmental Problems, Their Causes, and Sustainability 1

conservation biology Multidisciplinaryscience created to deal with the crisis ofmaintaining the genes, species, communities,and ecosystems that make up earth’sbiological diversity. Its goals are to investigatehuman impacts on biodiversity and todevelop practical approaches to preservingbiodiversity.conservationist Person concerned withusing natural areas and wildlife in waysthat sustain them for current and futuregenerations of humans and other forms oflife. Compare conservation biologist, ecologist,environmentalist, environmental scientist,preservationist, restorationist.conservation-tillage farming Crop cultivationin which the soil is disturbed little(minimum-tillage farming) or not at all (notillfarming) to reduce soil erosion, lowerlabor costs, and save energy. Compare conventional-tillagefarming.constancy Ability of a living system, suchas a population, to maintain a certain size.Compare inertia, resilience. See homeostasis.consumer Organism that cannot synthesizethe organic nutrients it needs and getsits organic nutrients by feeding on the tissuesof producers or of other consumers;generally divided into primary consumers(herbivores), secondary consumers (carnivores),tertiary (higher-level) consumers, omnivores,and detritivores (decomposers anddetritus feeders). In economics, one whouses economic goods.contour farming Plowing and plantingacross the changing slope of land, ratherthan in straight lines, to help retain waterand reduce soil erosion.contour strip mining Form of surfacemining used on hilly or mountainous terrain.A power shovel cuts a series of terracesinto the side of a hill. An earthmoverremoves the overburden, and a powershovel extracts the coal, with the overburdenfrom each new terrace dumped ontothe one below. Compare area strip mining,dredging, mountaintop removal, open-pit mining,subsurface mining.controlled burning Deliberately set, carefullycontrolled surface fires that reduceflammable litter and decrease the chances ofdamaging crown fires. See ground fire, surfacefire.conventional-tillage farming Cropcultivation method in which a planting surfaceis made by plowing land, breaking upthe exposed soil, and then smoothing thesurface. Compare conservation-tillage farming.convergent plate boundary Area whereearth’s lithospheric plates are pushedtogether. See subduction zone. Comparedivergent plate boundary, transform fault.coral reef Formation produced by massivecolonies containing billions of tinycoral animals, called polyps, that secrete astony substance (calcium carbonate) aroundthemselves for protection. When the coralsdie, their empty outer skeletons form layersand cause the reef to grow. They are foundin the coastal zones of warm tropical andsubtropical oceans.core Inner zone of the earth. It consists ofa solid inner core and a liquid outer core.Compare crust, mantle.corrective feedback loop See negative feedbackloop.corridors Long areas of land connectinghabitat that would otherwise becomefragmented.cost–benefit analysis (CBA) Estimatesand comparison of short-term and longtermbenefits (gains) and costs (losses) froman economic decision.cover crops The planting of crops such asalfalfa, clover, or rye immediately after harvestto help protect and hold the soil.critical mass Amount of fissionable nucleineeded to sustain a nuclear fission chainreaction.crop rotation Planting a field, or an areaof a field, with different crops from year toyear to reduce soil nutrient depletion. Aplant such as corn, tobacco, or cotton, whichremoves large amounts of nitrogen from thesoil, is planted one year. The next year alegume such as soybeans, which adds nitrogento the soil, is planted.crown fire Extremely hot forest fire thatburns ground vegetation and treetops.Compare controlled burning, ground fire, surfacefire.crude birth rate Annual number of livebirths per 1,000 people in the population ofa geographic area at the midpoint of a givenyear. Compare crude death rate.crude death rate Annual number ofdeaths per 1,000 people in the population ofa geographic area at the midpoint of a givenyear. Compare crude birth rate.crude oil Gooey liquid consisting mostlyof hydrocarbon compounds and smallamounts of compounds containing oxygen,sulfur, and nitrogen. Extracted from undergroundaccumulations, it is sent to oilrefineries, where it is converted to heatingoil, diesel fuel, gasoline, tar, and othermaterials.crust Solid outer zone of the earth. It consistsof oceanic crust and continental crust.Compare core, mantle.cultural eutrophication Overnourishmentof aquatic ecosystems with plant nutrients(mostly nitrates and phosphates) because ofhuman activities such as agriculture, urbanization,and discharges from industrialplants and sewage treatment plants. Seeeutrophication.cyanobacteria Single-celled, prokaryotic,microscopic organisms. Before being reclassifiedas monera, they were called bluegreenalgae.DDT Dichlorodiphenyltrichloroethane, achlorinated hydrocarbon that has beenwidely used as an insecticide but is nowbanned in some countries.death rate See crude death rate.debt-for-nature swap Agreement inwhich a certain amount of foreign debt iscanceled in exchange for local currencyinvestments that will improve naturalresource management or protect certainareas in the debtor country from harmfuldevelopment.deciduous plants Trees, such as oaks andmaples, and other plants that survive duringdry seasons or cold seasons by sheddingtheir leaves. Compare coniferous trees, succulentplants.decomposer Organism that digests partsof dead organisms and cast-off fragmentsand wastes of living organisms by breakingdown the complex organic molecules inthose materials into simpler inorganic compoundsand then absorbing the solublenutrients. Producers return most of thesechemicals to the soil and water for reuse.Decomposers consist of various bacteriaand fungi. Compare consumer, detritivore,producer.deductive reasoning Using logic to arriveat a specific conclusion based on a generalizationor premise. It goes from the generalto the specific. Compare inductive reasoning.defendant The individual, group ofindividuals, corporation, or governmentagency being charged in a lawsuit. Compareplaintiff.deforestation Removal of trees from aforested area without adequate replanting.degradable pollutant Potentially pollutingchemical that is broken down completelyor reduced to acceptable levels bynatural physical, chemical, and biologicalprocesses. Compare biodegradable pollutant,nondegradable pollutant, slowly degradablepollutant.degree of urbanization Percentage of thepopulation in the world, or a country, livingin areas with a population of more than2,500 people (higher in some countries).Compare urban growth.democracy Government by the peoplethrough their elected officials andappointed representatives. In a constitutionaldemocracy, a constitution provides the basisof government authority and puts restraintson government power through free electionsand freely expressed public opinion.demographic transition Hypothesis thatcountries, as they become industrialized,have declines in death rates followed bydeclines in birth rates.demography The study of the size, composition,and distribution of human populationsand the causes and consequences ofchanges in these characteristics.depletion time The time it takes to use acertain fraction, usually 80%, of the knownor estimated supply of a nonrenewableresource at an assumed rate of use. Findingand extracting the remaining 20% usuallycosts more than it is worth.desalination Purification of salt water orbrackish (slightly salty) water by removal ofdissolved salts.desert Biome in which evaporationexceeds precipitation and the averageamount of precipitation is less than 25 cen-G4GLOSSARY