EcologyEcology

PopulationsPopulationsEcosystemsEcosystemsSuccessionSuccessionHumans and the EnvironmentHumans and the Environment

Notes & Key: Ecology

Teacher Notes

PopulationPopulation

• Population sizePopulation size– Refers to the number of individuals in a Refers to the number of individuals in a

populationpopulation– Factors that influence this sizeFactors that influence this size

•Abiotic – nonliving, such as temperature, Abiotic – nonliving, such as temperature, moisture, air, salinity, and pHmoisture, air, salinity, and pH

•Biotic – all the living organisms that inhabit Biotic – all the living organisms that inhabit the environmentthe environment

• Population densityPopulation density– Refers to the number of individuals Refers to the number of individuals

found within a given areafound within a given area– If too wide spread, they rarely encounter If too wide spread, they rarely encounter

each other – difficult to reproduceeach other – difficult to reproduce

• DispersionDispersion– Refers to the way in which the Refers to the way in which the

individuals of the population are individuals of the population are arrangedarranged•Even – individuals are located at equal Even – individuals are located at equal

intervalsintervals

•Clumped – bunched together in clustersClumped – bunched together in clusters

•Random – location of each individual is Random – location of each individual is determined by chancedetermined by chance

• Population Growth – population grows Population Growth – population grows when more individuals are born than when more individuals are born than diedie

• Carrying capacity – when a population Carrying capacity – when a population has reached the maximum size that has reached the maximum size that the environment can supportthe environment can support– Size is determined by limiting factors Size is determined by limiting factors – Food, water, shelter Food, water, shelter

• Populations living areasPopulations living areas– Habitat = the area in which an organism Habitat = the area in which an organism

liveslives– Niche = the role the organism has in an Niche = the role the organism has in an

ecosystemecosystem

• Population relationshipsPopulation relationships– Symbiosis – close association between Symbiosis – close association between

two different types of organisms – a two different types of organisms – a scientific ‘living together’scientific ‘living together’•Mutualism – both organisms benefit (lichen)Mutualism – both organisms benefit (lichen)

•Commensalism – one organism benefits and Commensalism – one organism benefits and the other is neither harmed nor helped the other is neither harmed nor helped (epiphytes)(epiphytes)

•Parasitism – one organism benefits and the Parasitism – one organism benefits and the other is harmed (flea)other is harmed (flea)

EcosystemsEcosystems

• Energy FlowEnergy Flow– Producers - make their own food (green Producers - make their own food (green

plants, algae, some bacteria)plants, algae, some bacteria)– Consumers - obtain their food from others Consumers - obtain their food from others

•Herbivores – primary consumers that eat plantsHerbivores – primary consumers that eat plants•Carnivores – secondary consumers that eat fleshCarnivores – secondary consumers that eat flesh•Omnivores – secondary or tertiary consumers that Omnivores – secondary or tertiary consumers that

eat plants and flesheat plants and flesh•Decomposers – eat dead and decaying organismsDecomposers – eat dead and decaying organisms

• Food ChainFood Chain– Trophic levelsTrophic levels

•CloverClover

•RabbitRabbit

•SnakeSnake

•HawkHawk

• Food WebFood Web– Food chains that interconnectFood chains that interconnect– and overlapand overlap

• Pyramid of biomassPyramid of biomass– Total mass of organisms at each trophic Total mass of organisms at each trophic

levellevel

• Pyramid of numbersPyramid of numbers– Number of organisms at each trophic levelNumber of organisms at each trophic level

• Pyramid of energyPyramid of energy– Amount of energy at each trophic levelAmount of energy at each trophic level– Each trophic level receives ~ 10% from Each trophic level receives ~ 10% from

the next higher levelthe next higher level

• CyclesCycles– Water cycleWater cycle

•NonlivingNonliving– Condensation, precipitation, evaporationCondensation, precipitation, evaporation

•LivingLiving– Absorption, transpirationAbsorption, transpiration

• Carbon cycleCarbon cycle– Atmospheric carbonAtmospheric carbon– PhotosynthesisPhotosynthesis– Cellular respirationCellular respiration

• Nitrogen cycleNitrogen cycle– Atmospheric nitrogenAtmospheric nitrogen– Nitrogen-fixing bacteriaNitrogen-fixing bacteria– NitratesNitrates– NitritesNitrites– PlantsPlants– AnimalsAnimals– DecomposersDecomposers

• Oxygen cycleOxygen cycle– Oxygen in air and waterOxygen in air and water– Cellular respirationCellular respiration– WaterWater– PhotosynthesisPhotosynthesis

SuccessionSuccession

• Populations in an area are replaced Populations in an area are replaced by other populationsby other populations– Organisms make the environment less Organisms make the environment less

conducive for their existence and more conducive for their existence and more conducive for the next level conducive for the next level

• Primary succession – where life did Primary succession – where life did not exist beforenot exist before– Pioneer speciesPioneer species– Continuing species changeContinuing species change– Climax communityClimax community

– Ex. lichen, grasses, small bushes, small Ex. lichen, grasses, small bushes, small trees, mature softwoods (pines, balsams, trees, mature softwoods (pines, balsams, firs), mature hardwoods (oaks, hickories)firs), mature hardwoods (oaks, hickories)

• Secondary succession – where a prior Secondary succession – where a prior community was destroyed (by fire, community was destroyed (by fire, flood, volcanic eruption, abandoned flood, volcanic eruption, abandoned farming, mining, logging, etc.)farming, mining, logging, etc.)– Pioneer speciesPioneer species– Continuing species changeContinuing species change– Climax communityClimax community

Humans and the Humans and the EnvironmentEnvironment

• Conservation – Wise management of Conservation – Wise management of the Earth’s natural resourcesthe Earth’s natural resources– Renewable resourcesRenewable resources– Nonrenewable resourcesNonrenewable resources

• Renewable resourcesRenewable resources– WildlifeWildlife

•Many threatened or endangeredMany threatened or endangered

•Extinction occurs when a species disappears Extinction occurs when a species disappears from Earthfrom Earth

•Habitat destruction is major causeHabitat destruction is major cause

– ForestsForests• Becoming smaller due to increased demand for wood Becoming smaller due to increased demand for wood

and wood productsand wood products

• Deforestation occurs where large areas of forest are Deforestation occurs where large areas of forest are cut and cleared. Ex. tropical rainforestscut and cleared. Ex. tropical rainforests

– Cut and burned to clear land for farmingCut and burned to clear land for farming– Topsoil is thin, good for one, or maybe two, yearsTopsoil is thin, good for one, or maybe two, years– Then more must be clearedThen more must be cleared– When land is cleared, rain ceases as trees caused the When land is cleared, rain ceases as trees caused the

rain through transpirationrain through transpiration– Land becomes a desertLand becomes a desert

Reforestation is a solutionReforestation is a solution

• Soil – good soil is needed to grow Soil – good soil is needed to grow plants for food and for fibers to make plants for food and for fibers to make clothcloth– Erosion can be preventedErosion can be prevented

•WindbreaksWindbreaks

•Contour plowingContour plowing

•Terrace plowingTerrace plowing

•Strip croppingStrip cropping

•Crop rotationCrop rotation

• Nonrewable resourcesNonrewable resources– WaterWater

•Most importantMost important

•Cannot live without itCannot live without it

•WatershedsWatersheds

•DesalinationDesalination

Fossil FuelsFossil Fuels

Coal, natural gas, oilCoal, natural gas, oil

Alternative energy formsAlternative energy forms

solar energysolar energy

nuclear energynuclear energy

wind powerwind power

geothermal energygeothermal energy

water energywater energy

• PollutionPollution– Air pollutionAir pollution

• Most comes from burning fossil fuelsMost comes from burning fossil fuels

• Smog – smoke and fogSmog – smoke and fog

• Acid rain – oxides from burning fossil fuel combine Acid rain – oxides from burning fossil fuel combine with moisture in airwith moisture in air

• Temperature inversionTemperature inversion– Layer of warm air becomes trapped between layers of Layer of warm air becomes trapped between layers of

cool aircool air– Air pollutants become trapped in cool airAir pollutants become trapped in cool air– Do not rise form the earth, stay near groundDo not rise form the earth, stay near ground

– Water pollutionWater pollution•Agricultural runoffAgricultural runoff

• Industrial waste productsIndustrial waste products– One major example is hot waterOne major example is hot water– Causes thermal pollutionCauses thermal pollution– Hot water holds less oxygen than cold waterHot water holds less oxygen than cold water