Chapter 3Chapter 3

Ecosystems: Ecosystems: Connections in NatureConnections in Nature

Chapter Overview QuestionsChapter Overview Questions

What is ecology? What is ecology? What basic processes keep us and other What basic processes keep us and other

organisms alive?organisms alive? What are the major components of an What are the major components of an

ecosystem?ecosystem? What happens to energy in an ecosystem?What happens to energy in an ecosystem? What are soils and how are they formed?What are soils and how are they formed? What happens to matter in an ecosystem?What happens to matter in an ecosystem? How do scientists study ecosystems?How do scientists study ecosystems?

Core Case Study: Core Case Study: Have You Thanked the Insects Have You Thanked the Insects

Today?Today?

Many plant species depend on insects for Many plant species depend on insects for pollination.pollination.

Insect can control other pest insects by Insect can control other pest insects by eating themeating them

Core Case Study: Core Case Study: Have You Thanked the Insects Have You Thanked the Insects

Today?Today? ……if all insects disappeared, humanity if all insects disappeared, humanity

probably could not last more than a few probably could not last more than a few months [E.O. Wilson, Biodiversity expert].months [E.O. Wilson, Biodiversity expert]. InsectInsect’s role in nature is part of the larger ’s role in nature is part of the larger

biological community in which they live.biological community in which they live.

THE NATURE OF ECOLOGYTHE NATURE OF ECOLOGY

Ecology is a study Ecology is a study of connections in of connections in nature.nature. How organisms How organisms

interact with one interact with one another and with another and with their nonliving their nonliving environment.environment.

Communities

Subatomic Particles

Atoms

Molecules

Protoplasm

Cells

Tissues

Organs

Organ systems

Organisms

Populations

Populations

Communities

Ecosystems

Biosphere

Earth

Planets

Solar systems

Galaxies

Universe

Organisms

Realm of ecology

Ecosystems

Biosphere

Animation: Levels of OrganizationAnimation: Levels of Organization

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Organisms and SpeciesOrganisms and Species Organisms, the different forms of life on Organisms, the different forms of life on

earth, can be classified into different species earth, can be classified into different species based on certain characteristics.based on certain characteristics.

Insects751,000

Other animals281,000

Fungi69,000

Prokaryotes4,800

Plants248,400

Protists57,700

Known species1,412,000

Case Study: Case Study: Which Species Run the World?Which Species Run the World?

Multitudes of tiny microbes such as bacteria, Multitudes of tiny microbes such as bacteria, protozoa, fungi, and yeast help keep us alive.protozoa, fungi, and yeast help keep us alive. Harmful microbes are the minority.Harmful microbes are the minority. Soil bacteria convert nitrogen gas to a usable Soil bacteria convert nitrogen gas to a usable

form for plants.form for plants. They help produce foods (bread, cheese, yogurt, They help produce foods (bread, cheese, yogurt,

beer, wine).beer, wine). 90% of all living mass.90% of all living mass. Helps purify water, provide oxygen, breakdown Helps purify water, provide oxygen, breakdown

waste.waste. Lives beneficially in your body (intestines, nose).Lives beneficially in your body (intestines, nose).

Populations, Communities, and Populations, Communities, and EcosystemsEcosystems

Members of a species interact in groups Members of a species interact in groups called populations.called populations.

Populations of different species living and Populations of different species living and interacting in an area form a community.interacting in an area form a community.

A community interacting with its physical A community interacting with its physical environment of matter and energy is an environment of matter and energy is an ecosystem.ecosystem.

PopulationsPopulations

A population is a A population is a group of interacting group of interacting individuals of the individuals of the same species same species occupying a specific occupying a specific area.area. The space an The space an

individual or individual or population normally population normally occupies is its habitat.occupies is its habitat.

PopulationsPopulations

Genetic diversity Genetic diversity In most natural In most natural

populations populations individuals vary individuals vary slightly in their slightly in their genetic makeup.genetic makeup.

THE EARTHTHE EARTH’S LIFE SUPPORT ’S LIFE SUPPORT SYSTEMSSYSTEMS

The biosphere The biosphere consists of several consists of several physical layers that physical layers that contain:contain: AirAir WaterWater SoilSoil Minerals Minerals LifeLife

BiosphereBiosphere

AtmosphereAtmosphere Membrane of air around the planet.Membrane of air around the planet.

StratosphereStratosphere Lower portion contains ozone to filter out most of Lower portion contains ozone to filter out most of

the sunthe sun’s harmful UV radiation.’s harmful UV radiation.

HydrosphereHydrosphere All the earthAll the earth’s water: liquid, ice, water vapor’s water: liquid, ice, water vapor

LithosphereLithosphere The earthThe earth’s crust and upper mantle.’s crust and upper mantle.

Lithosphere (crust, top of upper mantle)

RockSoil

Vegetation and animals

Atmosphere

OceanicCrust

Continental Crust

LithosphereUpper mantle

AsthenosphereLower mantle

Mantle

Core

Biosphere

Crust

Crust (soil and rock)

Biosphere (living and dead

organisms)

Hydrosphere (water)

Atmosphere (air)

What Sustains Life on Earth?What Sustains Life on Earth?

Solar energy, Solar energy, the cycling of the cycling of matter, and matter, and gravity sustain gravity sustain the earththe earth’s life.’s life.

Nitrogencycle

Biosphere

Heat in the environment

Heat Heat Heat

Phosphoruscycle

Carboncycle

Oxygencycle

Watercycle

What Happens to Solar Energy What Happens to Solar Energy Reaching the Earth?Reaching the Earth?

Solar energy Solar energy flowing through flowing through the biosphere the biosphere warms the warms the atmosphere, atmosphere, evaporates and evaporates and recycles water, recycles water, generates winds generates winds and supports and supports plant growth.plant growth.

Absorbed by ozone Visible

Light

Absorbed by the earth

Greenhouse effect

UV radiation

Solarradiation

Energy in = Energy out

Reflected by atmosphere (34% ) Radiated by

atmosphere as heat (66%)

Heat radiated by the earth

Heat

Troposphere

Lower Stratosphere(ozone layer)

Animation: Sun to EarthAnimation: Sun to Earth

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ECOSYSTEM COMPONENTSECOSYSTEM COMPONENTS Life exists on land systems called biomes Life exists on land systems called biomes

and in freshwater and ocean aquatic life and in freshwater and ocean aquatic life zones.zones.

100–125 cm (40–50 in.)

Coastal mountain

ranges

SierraNevada

Mountains

GreatAmerican

Desert

Coastal chaparraland scrub

Coniferous forest

Desert Coniferous forest

Prairie grassland

Deciduous forest

1,500 m (5,000 ft.)3,000 m (10,000 ft.)

4,600 m (15,000 ft.)

Average annual precipitation

MississippiRiver Valley

AppalachianMountains

GreatPlains

RockyMountains

below 25 cm (0–10 in.)25–50 cm (10–20 in.)50–75 cm (20–30 in.)75–100 cm (30–40 in.)

Nonliving and Living Components of Nonliving and Living Components of EcosystemsEcosystems

Ecosystems consist of nonliving (abiotic) and Ecosystems consist of nonliving (abiotic) and living (biotic) components.living (biotic) components.

SunOxygen (O2)

Carbon dioxide (CO2)

Secondary consumer(fox)

Soil decomposers

Primaryconsumer

(rabbit)

PrecipitationFalling leaves

and twigs

Producer

Producers

Water

Animation: Roles of Organisms in an Animation: Roles of Organisms in an EcosystemEcosystem

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Animation: Diet of a Red FoxAnimation: Diet of a Red Fox

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Factors That Limit Population GrowthFactors That Limit Population Growth

Availability of matter and energy resources Availability of matter and energy resources can limit the number of organisms in a can limit the number of organisms in a population.population.

Zone of intolerance

Optimum rangeZone of physiological

stress

Zone of physiological

stress

Zone of intolerance

TemperatureLow High

Noorganisms

Feworganisms

Upper limit of tolerance

Po

pu

lati

on

siz

e

Abundance of organismsFew organisms

Noorganisms

Lower limit of tolerance

Factors That Limit Population GrowthFactors That Limit Population Growth

The physical The physical conditions of the conditions of the environment can environment can limit the limit the distribution of a distribution of a species.species.

Sugar Maple

Producers: Basic Source of All FoodProducers: Basic Source of All Food

Most producers capture sunlight to produce Most producers capture sunlight to produce carbohydrates by photosynthesis:carbohydrates by photosynthesis:

Producers: Basic Source of All FoodProducers: Basic Source of All Food

Chemosynthesis:Chemosynthesis: Some organisms such as deep ocean bacteria Some organisms such as deep ocean bacteria

draw energy from hydrothermal vents and draw energy from hydrothermal vents and produce carbohydrates from hydrogen sulfide produce carbohydrates from hydrogen sulfide (H(H22S) gas .S) gas .

Photosynthesis: Photosynthesis: A Closer LookA Closer Look

Chlorophyll molecules in the Chlorophyll molecules in the chloroplasts of plant cells chloroplasts of plant cells absorb solar energy.absorb solar energy.

This initiates a complex This initiates a complex series of chemical reactions series of chemical reactions in which carbon dioxide and in which carbon dioxide and water are converted to water are converted to sugars and oxygen.sugars and oxygen.

Sun

Chloroplastin leaf cell

Light-dependentReaction

Light-independent

reaction

Chlorophyll

Energy storage and release

(ATP/ADP)

Glucose

H2O

Sunlight

O2

CO2

6CO2 + 6 H2O C6H12O6 + 6 O2

Consumers: Eating and Recycling to Consumers: Eating and Recycling to SurviveSurvive

Consumers (heterotrophs) get their food by Consumers (heterotrophs) get their food by eating or breaking down all or parts of other eating or breaking down all or parts of other organisms or their remains.organisms or their remains. HerbivoresHerbivores

• Primary consumers that eat producersPrimary consumers that eat producers CarnivoresCarnivores

• Primary consumers eat primary consumersPrimary consumers eat primary consumers• Third and higher level consumers: carnivores that eat Third and higher level consumers: carnivores that eat

carnivores.carnivores. OmnivoresOmnivores

• Feed on both plant and animals.Feed on both plant and animals.

Decomposers and DetrivoresDecomposers and Detrivores

Decomposers: Recycle nutrients in ecosystems.Decomposers: Recycle nutrients in ecosystems. Detrivores: Insects or other scavengers that feed Detrivores: Insects or other scavengers that feed

on wastes or dead bodies.on wastes or dead bodies.

Scavengers

Powder broken down by decomposers into plant nutrients in soil

Bark beetle engraving

Decomposers

Long-horned beetle holes

Carpenter ant

galleries

Termite and

carpenter ant work Dry rot

fungus

Wood reduced to powder

Mushroom

Time progression

Aerobic and Anaerobic Respiration: Aerobic and Anaerobic Respiration: Getting Energy for SurvivalGetting Energy for Survival

Organisms break down carbohydrates and Organisms break down carbohydrates and other organic compounds in their cells to other organic compounds in their cells to obtain the energy they need.obtain the energy they need.

This is usually done through This is usually done through aerobic aerobic respirationrespiration.. The opposite of photosynthesisThe opposite of photosynthesis

Animation: Linked ProcessesAnimation: Linked Processes

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Aerobic and Anaerobic Respiration: Aerobic and Anaerobic Respiration: Getting Energy for SurvivalGetting Energy for Survival

Anaerobic respiration or fermentation:Anaerobic respiration or fermentation: Some decomposers get energy by breaking Some decomposers get energy by breaking

down glucose (or other organic compounds) in down glucose (or other organic compounds) in the absence of oxygen.the absence of oxygen.

The end products vary based on the chemical The end products vary based on the chemical reaction:reaction:• Methane gasMethane gas• Ethyl alcoholEthyl alcohol• Acetic acidAcetic acid• Hydrogen sulfideHydrogen sulfide

Two Secrets of Survival: Energy Flow Two Secrets of Survival: Energy Flow and Matter Recycleand Matter Recycle

An ecosystem An ecosystem survives by a survives by a combination of combination of energy flow and energy flow and matter recycling.matter recycling.

Abiotic chemicals(carbon dioxide,

oxygen, nitrogen, minerals)

Heat

Heat

Heat

Heat

Heat Solarenergy

Consumers(herbivores, carnivores)

Producers(plants)

Decomposers(bacteria, fungi)

Animation: Matter Recycling and Animation: Matter Recycling and Energy FlowEnergy Flow

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BIODIVERSITYBIODIVERSITY

Biodiversity Loss and Species Biodiversity Loss and Species Extinction: Remember HIPPOExtinction: Remember HIPPO

HH for for habitat destructionhabitat destruction and and degradationdegradation I I for for invasive speciesinvasive species PP for for pollutionpollution PP for for human population growthhuman population growth OO for for overexploitationoverexploitation

Why Should We Care About Why Should We Care About Biodiversity? Biodiversity?

Biodiversity provides us with:Biodiversity provides us with: Natural Resources (food water, wood, energy, Natural Resources (food water, wood, energy,

and medicines)and medicines) Natural Services (air and water purification, soil Natural Services (air and water purification, soil

fertility, waste disposal, pest control)fertility, waste disposal, pest control) Aesthetic pleasureAesthetic pleasure

SolutionsSolutions

Goals, strategies Goals, strategies and tactics for and tactics for protecting protecting biodiversity.biodiversity.

The Ecosystem Approach

Protect populations of species in their natural habitats

Goal

The Species Approach

Goal

Protect species from premature extinction

Preserve sufficient areas of habitats in different biomes and aquatic systems

Strategy

Tactics•Protect habitat areas through private purchase or government action

•Eliminate or reduce populations of nonnative species

from protected areas •Manage protected areas to sustain native species

•Restore degraded ecosystems

Tactics•Legally protect endangered species

•Manage habitat

•Propagate endangered

species in captivity

•Reintroduce species into

suitable habitats

Strategies

•Identify endangered species•Protect their critical habitats

ENERGY FLOW IN ECOSYSTEMSENERGY FLOW IN ECOSYSTEMS

Food chains and webs show how eaters, the Food chains and webs show how eaters, the eaten, and the decomposed are connected to eaten, and the decomposed are connected to one another in an ecosystem.one another in an ecosystem.

Heat

Heat

Heat

Heat

Heat

Heat Heat Heat

Detritivores (decomposers and detritus feeders)

First Trophic Level

Second TrophicLevel

Third Trophic Level

Fourth Trophic Level

Solar energy

Producers(plants)

Primary consumers(herbivores)

Secondary consumers(carnivores)

Tertiary consumers

(top carnivores)

Animation: Energy FlowAnimation: Energy Flow

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Animation: Prairie Trophic LevelsAnimation: Prairie Trophic Levels

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Food WebsFood Webs

Trophic levels are Trophic levels are interconnected interconnected within a more within a more complicated food complicated food web.web.

HumansBlue whale Sperm whale

Crabeater seal

Elephant seal

Killer whale

Leopard seal

Adelie penguins Emperor

penguin

Petrel FishSquid

Carnivorous plankton

Krill Herbivorous plankton

Phytoplankton

Animation: Categories of Food WebsAnimation: Categories of Food Webs

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Animation: Rainforest Food WebAnimation: Rainforest Food Web

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Animation: Prairie Food WebAnimation: Prairie Food Web

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Energy Flow in an Ecosystem: Losing Energy Flow in an Ecosystem: Losing Energy in Food Chains and WebsEnergy in Food Chains and Webs

In accordance with the 2In accordance with the 2ndnd law of law of thermodynamics, there is a decrease in the thermodynamics, there is a decrease in the amount of energy available to each amount of energy available to each succeeding organism in a food chain or web.succeeding organism in a food chain or web.

Energy Flow in an Ecosystem: Losing Energy Flow in an Ecosystem: Losing Energy in Food Chains and WebsEnergy in Food Chains and Webs

Ecological Ecological efficiencyefficiency: : percentage of percentage of useable energy useable energy transferred as transferred as biomass from biomass from one trophic level one trophic level to the next.to the next.

Heat

Heat

Heat

Heat

Heat

DecomposersTertiary

consumers(human)

Producers(phytoplankton)

Secondaryconsumers

(perch)

Primaryconsumers

(zooplankton)

10

100

1,000

10,000Usable energy

Available atEach tropic level(in kilocalories)

Animation: Energy Flow in Silver SpringsAnimation: Energy Flow in Silver Springs

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Productivity of Producers: Productivity of Producers: The Rate Is CrucialThe Rate Is Crucial

Gross primary Gross primary production production (GPP) (GPP) Rate at which an Rate at which an

ecosystemecosystem’s ’s producers producers convert solar convert solar energy into energy into chemical energy chemical energy as biomass.as biomass.

Gross primary productivity(grams of carbon per square meter)

Net Primary Production (NPP)Net Primary Production (NPP)

NPP = GPP – RNPP = GPP – R Rate at which Rate at which

producers use producers use photosynthesis to photosynthesis to store energy minus store energy minus the rate at which they the rate at which they use some of this use some of this energy through energy through respiration (R).respiration (R).

Photosynthesis

Sun

Net primary production (energy available to consumers)

Growth and reproduction

RespirationEnergy lost and unavailable to consumers

Gross primary production

What are natureWhat are nature’s three most productive and ’s three most productive and three least productive systems?three least productive systems?

Average net primary productivity (kcal/m2 /yr)

Open ocean

Continental shelfLakes and streams

EstuariesAquatic Ecosystems

Extreme desert

Desert scrub

Tundra (arctic and alpine)Temperate grassland

Woodland and shrublandAgricultural land

Savanna

North. coniferous forestTemperate forest

Terrestrial Ecosystems

Tropical rain forest

Swamps and marshes

SOIL: A RENEWABLE RESOURCESOIL: A RENEWABLE RESOURCE

Soil is a slowly renewed resource that Soil is a slowly renewed resource that provides most of the nutrients needed for provides most of the nutrients needed for plant growth and also helps purify water.plant growth and also helps purify water. Soil formation begins when bedrock is broken Soil formation begins when bedrock is broken

down by physical, chemical and biological down by physical, chemical and biological processes called processes called weatheringweathering..

Mature soilsMature soils, or soils that have developed , or soils that have developed over a long time are arranged in a series of over a long time are arranged in a series of horizontal layers called horizontal layers called soil horizonssoil horizons..

Fern

Mature soil

Honey fungus

Root system

Oak tree

Bacteria

Lords and ladies

Fungus

Actinomycetes

Nematode

Pseudoscorpion

Mite

RegolithYoung soil

Immature soil

Bedrock

Rockfragments

Moss and lichen

Organic debrisbuilds upGrasses and

small shrubs

Mole

Dog violet

Woodsorrel

EarthwormMillipede

O horizonLeaf litter

A horizon

Topsoil

B horizonSubsoil

C horizon

Parent material

Springtail

Red Earth Mite

Animation: Soil Profile Animation: Soil Profile

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Layers in Mature SoilsLayers in Mature Soils

Infiltration: the downward movement of water Infiltration: the downward movement of water through soil.through soil.

Leaching: dissolving of minerals and organic Leaching: dissolving of minerals and organic matter in upper layers carrying them to lower matter in upper layers carrying them to lower layers.layers.

The soil type determines the degree of The soil type determines the degree of infiltration and leaching.infiltration and leaching.

Soil Profiles of the Soil Profiles of the Principal Terrestrial Principal Terrestrial

Soil Types Soil Types

Mosaic of closely packed pebbles, boulders

Weak humus-mineral mixture

Dry, brown to reddish-brown with variable accumulations of clay, calcium and carbonate, and soluble salts

Alkaline, dark, and rich in humus

Clay, calcium compounds

Desert Soil(hot, dry climate)

Grassland Soilsemiarid climate)

Tropical Rain Forest Soil(humid, tropical climate)

Acidic light-colored humus

Iron and aluminum compounds mixed with clay

Deciduous Forest Soil(humid, mild climate)

Forest litter leaf moldHumus-mineral mixtureLight, grayish-brown, silt loamDark brown firm clay

Coniferous Forest Soil(humid, cold climate)

Light-colored and acidic

Acid litter and humus

Humus and iron and aluminum compounds

Some Soil PropertiesSome Soil Properties

Soils vary in the size Soils vary in the size of the particles they of the particles they contain, the amount contain, the amount of space between of space between these particles, and these particles, and how rapidly water how rapidly water flows through them.flows through them.

0.05–2 mmdiameter

High permeability Low permeability

WaterWater

Clayless than 0.002 mm

Diameter

Silt0.002–0.05 mm

diameter

Sand

MATTER CYCLING IN MATTER CYCLING IN ECOSYSTEMSECOSYSTEMS

Nutrient Cycles: Global RecyclingNutrient Cycles: Global Recycling Global Cycles recycle nutrients through the Global Cycles recycle nutrients through the

earthearth’s air, land, water, and living organisms.’s air, land, water, and living organisms. Nutrients are the elements and compounds that Nutrients are the elements and compounds that

organisms need to live, grow, and reproduce.organisms need to live, grow, and reproduce. Biogeochemical cycles move these substances Biogeochemical cycles move these substances

through air, water, soil, rock and living organisms.through air, water, soil, rock and living organisms.

The Water CycleThe Water Cycle

PrecipitationPrecipitation

Transpiration

Condensation

Evaporation

Ocean storage

Transpiration from plants

Precipitation to land

Groundwater movement (slow)

Evaporation from land Evaporation

from ocean Precipitation to ocean

Infiltration and Percolation

Rain clouds

RunoffSurface runoff

(rapid)

Surface runoff (rapid)

Animation: Hydrologic CycleAnimation: Hydrologic Cycle

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WaterWater’ Unique Properties’ Unique Properties There are strong forces of attraction between There are strong forces of attraction between

molecules of water.molecules of water. Water exists as a liquid over a wide Water exists as a liquid over a wide

temperature range. temperature range. Liquid water changes temperature slowly.Liquid water changes temperature slowly. It takes a large amount of energy for water to It takes a large amount of energy for water to

evaporate.evaporate. Liquid water can dissolve a variety of Liquid water can dissolve a variety of

compounds.compounds. Water expands when it freezes.Water expands when it freezes.

Effects of Human Activities Effects of Human Activities on Water Cycleon Water Cycle

We alter the water cycle by:We alter the water cycle by: Withdrawing large amounts of freshwater.Withdrawing large amounts of freshwater. Clearing vegetation and eroding soils.Clearing vegetation and eroding soils. Polluting surface and underground water.Polluting surface and underground water. Contributing to climate change.Contributing to climate change.

The Carbon Cycle:The Carbon Cycle:Part of NaturePart of Nature’s Thermostat’s Thermostat

Animation: Carbon CycleAnimation: Carbon Cycle

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Effects of Human Activities Effects of Human Activities on Carbon Cycleon Carbon Cycle

We alter the We alter the carbon cycle by carbon cycle by adding excess COadding excess CO22 to the atmosphere to the atmosphere through:through: Burning fossil fuels.Burning fossil fuels. Clearing vegetation Clearing vegetation

faster than it is faster than it is replaced.replaced.

CO

2 em

issi

on

s fr

om

fo

ssil

fu

els

(bil

lio

n m

etri

c to

ns

of

carb

on

eq

uiv

alen

t)

Year

Lowprojection

Highprojection

The Nitrogen Cycle: The Nitrogen Cycle: Bacteria in ActionBacteria in Action

Gaseous nitrogen (N2)in atmosphere

Ammonia, ammonium in soil Nitrogen-rich wastes,remains in soil

Nitrate in soil

Loss byleaching

Loss byleaching

Nitrite in soil

Nitrification

Nitrification

Ammonification

Uptake by autotrophsUptake by autotrophsExcretion, death,

decomposition

Loss bydenitrification

Food webs on land

Fertilizers

Nitrogen fixation

Animation: Nitrogen CycleAnimation: Nitrogen Cycle

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Effects of Human Activities Effects of Human Activities on the Nitrogen Cycleon the Nitrogen Cycle

We alter the nitrogen cycle by:We alter the nitrogen cycle by: Adding gases that contribute to acid rain.Adding gases that contribute to acid rain. Adding nitrous oxide to the atmosphere through Adding nitrous oxide to the atmosphere through

farming practices which can warm the farming practices which can warm the atmosphere and deplete ozone.atmosphere and deplete ozone.

Contaminating ground water from nitrate ions in Contaminating ground water from nitrate ions in inorganic fertilizers.inorganic fertilizers.

Releasing nitrogen into the troposphere through Releasing nitrogen into the troposphere through deforestation.deforestation.

Effects of Human Activities Effects of Human Activities on the Nitrogen Cycleon the Nitrogen Cycle

Human activities Human activities such as such as production of production of fertilizers now fix fertilizers now fix more nitrogen more nitrogen than all natural than all natural sources sources combined.combined.

Nitrogen fixation by natural processes

Glo

bal

nit

rog

en (

N)

fixa

tio

n(t

rilli

on

gra

ms)

Year

The Phosphorous CycleThe Phosphorous Cycle

Dissolvedin Ocean

Water

Marine Sediments Rocks

uplifting overgeologic time

settling out weatheringsedimentation

LandFoodWebs

Dissolvedin Soil Water,Lakes, Rivers

death,decomposition

uptake byautotrophs

agriculture

leaching, runoff

uptake byautotrophs

excretion

death,decomposition

mining Fertilizer

weathering

Guano

MarineFoodWebs

Animation: Phosphorous CycleAnimation: Phosphorous Cycle

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Effects of Human Activities Effects of Human Activities on the Phosphorous Cycleon the Phosphorous Cycle

We remove large amounts of phosphate from We remove large amounts of phosphate from the earth to make fertilizer.the earth to make fertilizer.

We reduce phosphorous in tropical soils by We reduce phosphorous in tropical soils by clearing forests.clearing forests.

We add excess phosphates to aquatic We add excess phosphates to aquatic systems from runoff of animal wastes and systems from runoff of animal wastes and fertilizers.fertilizers.

The Sulfur CycleThe Sulfur Cycle

Hydrogen sulfide

Sulfur

Sulfate salts

Decaying matter

Animals

Plants

Ocean

IndustriesVolcano

Hydrogen sulfideOxygen

Dimethyl sulfide

Ammoniumsulfate

Ammonia

Acidic fog and precipitationSulfuric acid

WaterSulfurtrioxide

Sulfur dioxide

Metallicsulfidedeposits

Animation: Sulfur CycleAnimation: Sulfur Cycle

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Effects of Human Activities Effects of Human Activities on the Sulfur Cycleon the Sulfur Cycle

We add sulfur dioxide to the atmosphere by:We add sulfur dioxide to the atmosphere by: Burning coal and oilBurning coal and oil Refining sulfur containing petroleum.Refining sulfur containing petroleum. Convert sulfur-containing metallic ores into free Convert sulfur-containing metallic ores into free

metals such as copper, lead, and zinc releasing metals such as copper, lead, and zinc releasing sulfur dioxide into the environment.sulfur dioxide into the environment.

The Gaia Hypothesis:The Gaia Hypothesis: Is the Earth Alive? Is the Earth Alive?

Some have proposed that the earthSome have proposed that the earth’s various ’s various forms of life control or at least influence its forms of life control or at least influence its chemical cycles and other earth-sustaining chemical cycles and other earth-sustaining processes.processes. The strong Gaia hypothesis: life The strong Gaia hypothesis: life controlscontrols the the

earthearth’s life-sustaining processes.’s life-sustaining processes. The weak Gaia hypothesis: life The weak Gaia hypothesis: life influencesinfluences the the

earthearth’s life-sustaining processes.’s life-sustaining processes.

HOW DO ECOLOGISTS LEARN ABOUT HOW DO ECOLOGISTS LEARN ABOUT ECOSYSTEMS?ECOSYSTEMS?

Ecologist go into ecosystems to observe, but Ecologist go into ecosystems to observe, but also use remote sensors on aircraft and also use remote sensors on aircraft and satellites to collect data and analyze satellites to collect data and analyze geographic data in large databases.geographic data in large databases. Geographic Information SystemsGeographic Information Systems Remote SensingRemote Sensing

Ecologists also use controlled indoor and Ecologists also use controlled indoor and outdoor chambers to study ecosystemsoutdoor chambers to study ecosystems

Geographic Information Systems (GIS)Geographic Information Systems (GIS)

A GIS organizes, A GIS organizes, stores, and analyzes stores, and analyzes complex data complex data collected over broad collected over broad geographic areas.geographic areas.

Allows the Allows the simultaneous simultaneous overlay of many overlay of many layers of data.layers of data.

Critical nesting sitelocations

USDA Forest ServiceUSDA

Forest ServicePrivateowner 1 Private owner 2

Topography

Habitat type

LakeWetlandForest

Grassland

Real world

Systems AnalysisSystems Analysis

Ecologists develop Ecologists develop mathematical and mathematical and other models to other models to simulate the simulate the behavior of behavior of ecosystems.ecosystems.

SystemsMeasurement

Define objectivesIdentify and inventory variablesObtain baseline data on variables

Make statistical analysis of relationships among variables

Determine significant interactions

Objectives Construct mathematical model describing interactions among variables

Run the model on a computer, with values entered for differentVariables

Evaluate best ways to achieve objectives

DataAnalysis

SystemModeling

SystemSimulation

SystemOptimization

Importance of Baseline Importance of Baseline Ecological DataEcological Data

We need baseline data on the worldWe need baseline data on the world’s ’s ecosystems so we can see how they are ecosystems so we can see how they are changing and develop effective strategies for changing and develop effective strategies for preventing or slowing their degradation.preventing or slowing their degradation. Scientists have less than half of the basic Scientists have less than half of the basic

ecological data needed to evaluate the status of ecological data needed to evaluate the status of ecosystems in the United Sates (Heinz ecosystems in the United Sates (Heinz Foundation 2002; Millennium Assessment 2005).Foundation 2002; Millennium Assessment 2005).