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