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Ecosystems: What Are Ecosystems: What Are They and How Do They They and How Do They
Work?Work?
Chapter 4Chapter 4
Key ConceptsKey Concepts
What is ecology?What is ecology?
Major components of ecosystemsMajor components of ecosystems
Energy flow and matter cyclesEnergy flow and matter cycles
What are soils and how do they form?What are soils and how do they form?
Ecosystem studiesEcosystem studies
Importance of InsectsImportance of Insects
PollinationPollination
Pest controlPest control
Important roles in Important roles in biological communitybiological community
Fig. 3-1, p. 35
Importance of InsectsImportance of Insects
Fig. 3-1, p. 35
Nature of EcologyNature of Ecology
What is ecology?What is ecology?
OrganismsOrganisms
CellsCells
SpeciesSpecies
Microbes rule!Microbes rule!
Fig. 3-2, p. 37
Nature of EcologyNature of Ecology
Fig. 3-2, p. 37
Insects751,000
Protists57,700
Plants248,400
Prokaryotes4,800
Fungi69,000
Other animals281,000
Known species1,412,000
Populations, Communities, and Populations, Communities, and EcosystemsEcosystems
PopulationsPopulations
Genetic diversityGenetic diversity
Biological communityBiological community
EcosystemsEcosystems
BiosphereBiosphere
Population of Monarch Population of Monarch ButterfliesButterflies
Fig. 3-3, p. 37
Genetic Diversity in One Snail Genetic Diversity in One Snail SpeciesSpecies
Fig. 3-4, p. 38
What Sustains Life on Earth?What Sustains Life on Earth?
TroposphereTroposphere
StratosphereStratosphere
HydrosphereHydrosphere
LithosphereLithosphere
BiosphereBiosphere
Fig. 3-5, p. 38
Fig. 3-5, p. 38
Atmosphere
Biosphere
CrustLower mantle
AsthenosphereUpper mantle
Continentalcrust
Oceaniccrust
LithosphereVegetationand animals
Soil
Rock
Crust (soiland rock)
Atmosphere(air)
Biosphere(living and dead
organisms)
Lithosphere(crust, top of upper mantle)
Hydrosphere(water)
Core
Mantle
What Sustains Life on Earth?What Sustains Life on Earth?
Earth’s Life-Support SystemsEarth’s Life-Support Systems
One way flow of One way flow of high-quality energyhigh-quality energy
Cycling of matterCycling of matter
GravityGravity
Fig. 3-6, p. 39
Fig. 3-6, p. 39
Biosphere
Carboncycle
Phosphoruscycle
Nitrogencycle
Watercycle
Oxygencycle
Heat in the environment
HeatHeatHeat
Earth’s Life-Support SystemsEarth’s Life-Support Systems
Flow of Solar Energy to and from Flow of Solar Energy to and from the Earththe Earth
Greenhouse gasesGreenhouse gases
Greenhouse effectGreenhouse effect
Fig. 3-7, p. 40
Heat radiatedby the earth
Solarradiation
Absorbedby ozone
UV radiation
Visiblelight
Absorbedby theearth
Reflected byatmosphere (34%)
Energy in = Energy out
Radiated byatmosphereas heat (66%)
Lower Stratosphere(ozone layer)
Troposphere Greenhouseeffect
Heat
Flow of Solar Energy to and from Flow of Solar Energy to and from the Earththe Earth
Fig. 3-7, p. 40
Why is the Earth so Favorable Why is the Earth so Favorable for Life?for Life?
Liquid waterLiquid water
TemperatureTemperature
GravityGravity
AtmosphereAtmosphere
Ecosystem ComponentsEcosystem Components
BiomesBiomes
Aquatic life zonesAquatic life zones
Freshwater life zonesFreshwater life zones
Ocean or marine life zonesOcean or marine life zones
Abiotic and biotic componentsAbiotic and biotic components
Range of toleranceRange of tolerance
Law of toleranceLaw of tolerance
Fig. 3-8, p. 41
Coniferous forest Desert Coniferous forest Prairie grassland Deciduous forest
100–125 cm (40–50 in.)75–100 cm (30–40 in.)50–75 cm (20–30 in.)25–50 cm (10–20 in.)below 25 cm (0–10 in.)
Average annual precipitation
4,600 m (15,000 ft.)3,000 m (10,000 ft.)1,500 m (5,000 ft.)
Coastal mountainranges
Sierra NevadaMountains
Great AmericanDesert
RockyMountains
GreatPlains
MississippiRiver Valley
AppalachianMountains
Coastal chaparraland scrub
Major BiomesMajor Biomes
Sun
Producers (rooted plants)
Producers (phytoplankton)
Primary consumers (zooplankton)
Secondary consumers (fish)
Dissolvedchemicals
Tertiary consumers
(turtles)
Sediment
Decomposers (bacteria and fungi)
Fig. 3-9, p. 42
Major Components of Freshwater EcosystemsMajor Components of Freshwater Ecosystems
Sun
Producer
PrecipitationFalling leaves
and twigs
Producers
Primary consumer(rabbit)
Secondary consumer(fox)
Carbon dioxide (CO2)
Oxygen (O2)
Water
Soil decomposers
Soluble mineral nutrients
Fig. 3-10, p. 42
Major Components of a Field Major Components of a Field EcosystemEcosystem
Lower limitof tolerance
Upper limitof tolerance
TemperatureLow High
Abundance of organismsFew
organismsFew
organismsNo
organismsNo
organisms
Zone ofintoleranceZone of
physiological stress
Zone ofintolerance Zone of
physiological stress
Optimum range
Po
pu
lati
on
Siz
e
Fig. 3-11, p. 43
Range of ToleranceRange of Tolerance
Factors Limiting Population GrowthFactors Limiting Population Growth
Limiting factorsLimiting factors
Limiting factor principleLimiting factor principle
Excess water or water shortages for terrestrial organismsExcess water or water shortages for terrestrial organisms
Excess or lack of soil nutrientsExcess or lack of soil nutrients
Dissolved oxygen for aquatic organismsDissolved oxygen for aquatic organisms
Salinity for aquatic organismsSalinity for aquatic organisms
Major Biological Components of Major Biological Components of EcosystemsEcosystems
Producers (autotrophs)Producers (autotrophs)
PhotosynthesisPhotosynthesis
ChemosynthesisChemosynthesis
Consumers (heterotrophs)Consumers (heterotrophs)
Consumers: Feeding and Consumers: Feeding and RespirationRespiration
DecomposersDecomposers
OmnivoresOmnivores
DetritivoresDetritivores
Aerobic respirationAerobic respiration
MushroomWoodreduced
to powder
Long-hornedbeetle holes
Bark beetleengraving
Carpenterant
galleries
Termite andcarpenter
antwork Dry rot fungus
Detritus feeders Decomposers
Time progression Powder broken down by decomposersinto plant nutrients in soil
Fig. 3-12, p. 44
DetritivoresDetritivores
Fig. 3-13, p. 45
Decomposersbacteria, fungi)
Solarenergy
HeatHeat
Heat Heat
Heat
Abiotic chemicals(carbon dioxide,
oxygen, nitrogen,minerals)
Consumers(herbivores,carnivores)
Producers(plants)
Main Structural Components of Main Structural Components of an Ecosysteman Ecosystem
Fig. 3-14, p. 45
BiodiversityBiodiversity
Fig. 3-15, p. 46
Examples of BiodiversityExamples of Biodiversity
Food Chains and Food WebsFood Chains and Food Webs
Food chainFood chain
Trophic levelTrophic level
Food webFood web
Fig. 3-16, p. 47
First TrophicLevel
Second TrophicLevel
Third TrophicLevel
Fourth TrophicLevel
Producers(plants)
Primaryconsumers(herbivores)
Secondaryconsumers(carnivores)
Tertiaryconsumers
(top carnivores)
Detritivoresdecomposers and detritus feeders)
Solarenergy
Heat
Heat Heat Heat
HeatHeat
Heat
Heat
Model of a Food ChainModel of a Food Chain
Humans
Blue whale Sperm whale
Crabeater seal
Killer whale Elephantseal
Leopardseal
Petrel
Fish Squid
Carnivorous plankton
Krill
Phytoplankton
Herbivorouszooplankton
Emperorpenguin
Fig. 3-17, p. 48
Food Web in the AntarcticFood Web in the Antarctic
Adéliepenguins
Energy Flow in an EcosystemEnergy Flow in an Ecosystem
BiomassBiomass
Ecological efficiencyEcological efficiency
Pyramid of energy flowPyramid of energy flow
Fig. 3-18, p. 49
Secondaryconsumers
(perch)
10
100
1,000
10,000Usable energy
available ateach tropic level(in kilocalories)
Heat
Heat
Heat
Heat
Heat
Producers(phytoplankton)
Tertiaryconsumers
(human)
Primaryconsumers
(zooplankton)
Pyramid of Energy FlowPyramid of Energy Flow
Decomposers
Biomass ProductivityBiomass Productivity
Gross primary productivity (GPP)Gross primary productivity (GPP)
Net primary productivity (NPP)Net primary productivity (NPP)
NPP and populationsNPP and populations
Fig. 3-19, p. 49
Energy lost andunavailable toconsumers
Respiration
Growth and reproduction
Sun
Photosynthesis
Gross primaryproduction
Net primaryproduction(energyavailable toconsumers)
Differences between GPP and NPPDifferences between GPP and NPP
Fig. 3-20, p. 50
Swamps and marshes
Tropical rain forest
Temperate forest
Northern coniferous forest
(taiga)
Savanna
Agricultural land
Woodland and shrubland
Temperate grassland
Tundra (arctic and alpine)
Desert scrub
Extreme desert
Aquatic EcosystemsEstuaries
Lakes and streams
Continental shelf
Open ocean
Terrestrial Ecosystems
800 1,600 2,400 3,200 4,000 4,800 5,600 6,400 7,200 8,000 8,800 9,600
Average net primary productivity (kcal/m2/yr)
Net Primary Productivity in Major Net Primary Productivity in Major Life Zones and EcosystemsLife Zones and Ecosystems
Ecosystems: What Are Ecosystems: What Are They and How Do They They and How Do They
Work?Work?
Chapter 3Chapter 3
Sections 5-7Sections 5-7
SoilsSoils
Origins of soilsOrigins of soils
Soil horizons: O, A, B, and CSoil horizons: O, A, B, and C
Soil profilesSoil profiles
Infiltration and leachingInfiltration and leaching
Oak tree
Woodsorrel
Lords andladies
EarthwormDog violet
MoleMillipede
Honeyfungus
Organic debrisbuilds up
Moss andlichen
Rockfragments
Bedrock
Immature soil
Regolith
Young soil
PseudoscorpionMite
Nematode
Actinomycetes
FungusBacteria
SpringtailRed earthmite
Mature soil
Root system
C horizonParent material
B horizonSubsoil
A horizonTopsoil
Grasses andsmall shrubs
Fern
Fig. 3-21, p. 51
Soil Formation and HorizonsSoil Formation and Horizons
O horizonLeaf litter
Fig. 3-22, p. 52
Soil Profiles Soil Profiles from Different from Different
EcosystemsEcosystems
Weak humus-mineral mixture
Mosaicof closelypackedpebbles,boulders
Dry, brown toreddish-brown, with variable accumulationsof clay, calciumcarbonate, andsoluble salts
Desert Soil(hot, dry climate)
Grassland Soil(semiarid climate)
Alkaline,dark,and richin humus
Clay,calciumcompounds
Fig. 3-22a, p. 52
Soil Profiles from Different Soil Profiles from Different EcosystemsEcosystems
Soil Profiles from Different Soil Profiles from Different EcosystemsEcosystems
Acidiclight-coloredhumus
Iron andaluminumcompoundsmixed withclay
Forest litterleaf mold
Humus-mineralmixture
Light, grayish-brown, silt loam
Dark brownFirm clay
Acid litterand humus
Humus andiron andaluminumcompounds
Light-coloredand acidic
Tropical Rain Forest Soil(humid, tropical climate)
Deciduous Forest Soil(humid, mild climate)
Coniferous Forest Soil(humid, cold climate)
Fig. 3-22b, p. 52
pHpH
Acidity or alkalinity of water or water-bearing samplesAcidity or alkalinity of water or water-bearing samples
Scale 0-14Scale 0-14
Acidic: pH 0-6.9Acidic: pH 0-6.9
Neutral pH 7.0Neutral pH 7.0
Alkaline (basic): pH 7.1-14Alkaline (basic): pH 7.1-14
The pH ScaleThe pH Scale
Fig. 3-23, p. 192
Matter Cycling in Ecosystems: Matter Cycling in Ecosystems: Biogeochemical CyclesBiogeochemical Cycles
Nutrient (biogeochemical) cyclesNutrient (biogeochemical) cycles
Hydrologic (water) cycleHydrologic (water) cycle
Carbon cycleCarbon cycle
Nitrogen cycleNitrogen cycle
Phosphorus cyclePhosphorus cycle
Sulfur cycleSulfur cycle
PrecipitationPrecipitation
to land
Evaporation
EvaporationFromocean
Ocean storage
Condensation
Transpiration
Rain clouds
Infiltration andpercolation
Transpirationfrom plants
Groundwater movement (slow)
Precipitation
Simplified Hydrologic (Water) CycleSimplified Hydrologic (Water) Cycle
Fig. 3-24, p. 54
Surface runoff (rapid)
EvaporationFromocean
RapidPrecipitatio
nto ocean
Surface runoff (rapid)
Human Intervention in the Human Intervention in the Hydrologic CycleHydrologic Cycle
Large withdraw of surface and ground watersLarge withdraw of surface and ground waters
Clearing vegetationClearing vegetation
PollutionPollution
Diffusion betweenatmosphere and ocean
Carbon dioxidedissolved inocean water
Marine food websProducers, consumers,
decomposers, detritivores
Marine sediments, includingformations with fossil fuels
Combustion of fossil fuels
Fig. 3-25a, p. 56
The Carbon Cycle (Marine)The Carbon Cycle (Marine)
sedimentation
uplifting over geologic time
photosynthesis aerobic respiration
death, sedimentation
incorporation into sediments
Atmosphere(most carbon is in carbon dioxide)
Terrestrialrocks
Land food websProducers, consumers,
decomposers, detritivores
Peat,fossil fuels
Soil water(dissolved carbon)
Combustionof fossil
fuelsvolcanic action
Fig. 3-25b, p. 57
The Carbon Cycle (Terrestrial)The Carbon Cycle (Terrestrial)
photosynthesis
death, burial, compaction over geologic time
aerobic respiration
deforestaion
combustion of wood (for clearing
land; or fuel)
weathering
leaching, runoff
Fig. 3-26, p. 56
Highprojection
Lowprojection
Human Interference in the Global Human Interference in the Global Carbon CycleCarbon Cycle
Gaseous Nitrogen (N2)in AtmosphereNitrogen
Fixationby industry
for agricultureFood Webs
on Land
Fertilizersuptake byautotrophs
excretion, death,decomposition
uptake byautotrophs
Nitrogenous Wastes,Remains in Soil
NO3–
in Soil
NO2–
in Soilloss by
leaching
1. Nitrificationbacteria convert NH4
+
to nitrite (NO2–)
2. Nitrificationbacteria convert NO2
–
to nitrate (NO3–)
Ammonificationbacteria, fungi convert the
residues to NH3; thisdissolves to form NH4
+
NH3, NH4+
in Soil
loss byleaching
Nitrogen Fixationbacteria convert N2 toammonia (NH3); this
dissolves to formammonium (NH4
+)
Denitrificationby bacteria
Fig. 3-27, p. 58
The Nitrogen CycleThe Nitrogen Cycle
Fig. 3-28, p. 58
Nitrogen fixation by natural processes
Nitrogen fixationbypr
oces
ses
human
Human Interference in the Global Human Interference in the Global Nitrogen CycleNitrogen Cycle
Marine Sediments Rocks
Marine Food Webs
Dissolvedin Ocean
Water
Dissolvedin Soil Water,Lakes, Rivers
LandFoodWebs
Guano
Fertilizer
excretion
uptake byautotrophs
death,decomposition
sedimentation settling outuplifting overgeologic time
weathering
uptake byautotrophs
weathering
mining
leaching, runoff
agriculture
Fig. 3-29, p. 59
The Phosphorus CycleThe Phosphorus Cycle
Ocean
Hydrogen sulfide
Industries
Volcano
Oxygen
Water AmmoniaSulfur trioxide Sulfuric acid Acidic fog and precipitation
Ammonium sulfate
Plants
Animals
Sulfate salts
Hydrogen sulfide
SulfurDecaying matterMetallicSulfidedeposits
Dimethyl sulfide
Sulfur dioxide
Fig. 3-30, p. 60
The Sulfur CycleThe Sulfur Cycle
How Do Ecologists Learn How Do Ecologists Learn about Ecosystems?about Ecosystems?
Field researchField research
Remote sensingRemote sensing
Geographic information system (GIS)Geographic information system (GIS)
Laboratory researchLaboratory research
Systems analysisSystems analysis
Fig. 3-31, p. 61
Wetland Lake
Critical nesting site locations
USDA Forest Service
Topography
Habitat type
Real world
Privateowner 1
Private owner 2
USDAForest Service
Grassland
Forest
Geographic Information System (GIS)Geographic Information System (GIS)
Stepped ArtSystemOptimization
Define objectives
Identify and inventory variables
Obtain baseline data on variables
Make statistical analysis of relationships among variables
Determine significant interactions
Construct mathematical model describing interactions among variables
Run the model on a computer, with values entered for different variables
Evaluate best ways to achieve objectives
Fig. 3-32, p. 61
SystemSimulation
DataAnalysis
SystemModeling
SystemsMeasurement
Stages of Systems AnalysisStages of Systems Analysis
Importance of Baseline Importance of Baseline Ecological DataEcological Data
To understand nature, current conditions must To understand nature, current conditions must be knownbe known
Baseline data are lackingBaseline data are lacking
Long-term sustainabilityLong-term sustainability