Ecosystems: Components, Energy Flow, and Matter Cycling“All things come from earth, and to earth they all return”—Menander

Ecology and the levels of organization of matter

Ecology—Greek oikos meaning houseStudy of how organisms interact with one another and their non-living environment (biotic and abiotic components) Studies connections in nature on the thin life supporting membrane of air, water, and soil Levels of Organization of Matter

Subatomic to biosphere

Ecosystem OrganizationOrganisms

Made of cellsEukaryotic vs Prokaryotic

SpeciesGroups of organisms that resemble one another in appearance, behavior, and genetic make upSexual vs Asexual reproductionProduction of viable offspring in nature1.5 million named; 10-14 million likely

PopulationsGenetic diversity

CommunitiesEcosystemsBiosphere

Fig. 4.2, p. 66

BiosphereBiosphere

Ecosystems

Communities

Populations

Organisms

Earth’s Life Support SystemsTroposphere

To 11 milesAir is here

Stratosphere11 to 30 milesOzone layer

HydrosphereSolid, liquid, and gaseous water

LithosphereCrust and upper mantleContains non-renewable res.

Atmosphere

Vegetation and animals

Soil

Rock

Biosphere

Crust

core

MantleLithosphere

Crust

Lithosphere(crust, top of upper mantle)

Hydrosphere(water)

Atmosphere(air)

Biosphere(Living and dead

organisms)

Crust(soil and rock)

Sustaining Life on Earth…

One way flow of high quality energyThe cycling of matter (the earth is a closed system)Gravity

Causes downward movement of matter

Biosphere

Carboncycle

Phosphoruscycle

Nitrogencycle

Watercycle

Oxygencycle

Heat in the environment

Heat Heat Heat

Major Ecosystem Components

Abiotic ComponentsWater, air, temperature, soil, light levels, precipitation, salinitySets tolerance limits for populations and communitiesSome are limiting factors that structure the abundance of populations

Biotic ComponentsProducers, consumers, decomposersPlants, animals, bacteria/fungiBiotic interactions with biotic components include predation, competition, symbiosis, parasitism, commensalism etc.

Limiting Factors on Land & in H2O

TerrestrialSunlightTemperaturePrecipitationSoil nutrientsFire frequencyWindLatitudeAltitude

Aquatic/MarineLight penetration

• Water clarity

Water currentsDissolved nutrient concentrations

• Esp. N, P, Fe

Dissolved Oxygen concentrationSalinity

The Source of High Quality EnergyEnergy of sun lights and warms the planetSupports PSNPowers the cycling of matterDrives climate and weather that distribute heat and H2O

Solarradiation

Energy in = Energy out

Reflected byatmosphere (34%)

UV radiation

Absorbedby ozone

Absorbedby the earth

Visiblelight

Lower Stratosphere(ozone layer)

Troposphere

Heat

GreenhouseGreenhouseeffecteffect

Radiated byatmosphere

as heat (66%)

Earth

Heat radiatedby the earth

Fate of Solar Energy…Earth gets 1/billionth of sun’s output of energy34% is reflected away by atmosphere66% is absorbed by chemicals in atmosphere = re-radiated into space Visible light, Infrared radiation (heat), and a small amount of UV not absorbed by ozone reaches the atmosphereEnergy warms troposphere and land

Evaporates water and cycles it along with gravityGenerates windsA tiny fraction is captured by photosynthesizing organisms

Natural greenhouse effect vs. Global Warming

Primary Productivity

The conversion of light energy to chemical energy is called “gross primary production.”Plants use the energy captured in photosynthesis for maintenance and growth.The energy that is accumulated in plant biomass is called “net primary production.”

Primary ProductivityNPP=GPP-respiration rateGPP= RATE at which producers convert solar energy into chemical energy as biomass

Rate at which producers use photosynthesis to fix inorganic carbon into the organic carbon of their tissuesThese producers must use some of the total biomass they produce for their own respiration

NPP= Rate at which energy for use by consumers is stored in new biomass (available to consumers)Units Kcal/m2/yr or g/m2/yr How do you measure it? AP Lab SiteMost productive vs. least productive

What are the most productive Ecosystems?

EstuariesEstuaries

Swamps and marshesSwamps and marshes

Tropical rain forestTropical rain forest

Temperate forestTemperate forest

Northern coniferous forest (taiga)Northern coniferous forest (taiga)

SavannaSavanna

Agricultural landAgricultural land

Woodland and shrublandWoodland and shrubland

Temperate grasslandTemperate grassland

Lakes and streamsLakes and streams

Continental shelfContinental shelf

Open oceanOpen ocean

Tundra (arctic and alpine)Tundra (arctic and alpine)

Desert scrubDesert scrub

Extreme desertExtreme desert

800800 1,6001,600 2,4002,400 3,2003,200 4,0004,000 4,8004,800 5,6005,600 6,4006,400 7,2007,200 8,0008,000 8,8008,800 9,6009,600

Average net primary productivity (kcal/mAverage net primary productivity (kcal/m22/yr)/yr)

Fate of Primary Productivity and Some important questions…

Since producers are ultimate source of all food, why shouldn’t we just harvest the plants of the world’s marshes?Why don’t we clear cut tropical rainforests to grow crops for humans?Why not harvest primary producers of the world’s vast oceans?Vitousek et al: Humans now use, waste, or destroy about 27% of earth’s total potential NPP and 40% of the NPP of the planet’s terrestrial ecosystems

Biotic Components of Ecosystems

Heat

Heat Heat

Heat

Heat

Abiotic chemicalsAbiotic chemicals(carbon dioxide,(carbon dioxide,

oxygen, nitrogen,oxygen, nitrogen,minerals)minerals)

ProducersProducers(plants)(plants)

DecomposersDecomposers(bacteria, fungus)(bacteria, fungus)

ConsumersConsumers(herbivores, (herbivores, carnivores)carnivores)

Solarenergy

Producers (autotrophs)Source of all food

PhotosynthesisConsumers=heterotrophAerobic respirationAnaerobic respiration

Methane, H2S

DecomposersMatter recyclers…Release organic compounds into soil and water where they can be used by producers

Trophic LevelsEach organism in an ecosystem is assigned to a feeding (or Trophic) levelPrimary ProducersPrimary Consumers (herbivores)Secondary Consumer (carnivores)Tertiary ConsumersOmnivoresDetritus feeders and scavengers

Directly consume tiny fragments of dead stuff

DecomposersDigest complex organic chemicals into inorganic nutrients that are used by producersComplete the cycle of matter

Detritivores vs Decomposers stop

Fig. 4.15, p. 75

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

Energy Flow and Matter Cycling in Ecosystems…

Food Chains vs. Food WebsKEY: There is little if no matter waste in natural ecosystems!

Heat Heat Heat Heat

Heat

Heat

Heat

First TrophicLevel

Second TrophicLevel

Third TrophicLevel

Fourth TrophicLevel

Solarenergy

Producers(plants)

Primaryconsumers(herbivores)

Tertiaryconsumers

(top carnivores)

Secondaryconsumers(carnivores)

Detritvores(decomposers and detritus feeders)

Generalized Food Web of the Antarctic

Fig. 4.18, p. 77

Humans

Blue whale Sperm whale

Crabeater seal

Killerwhale Elephant

seal

Leopardseal

Adéliepenguins Petrel

Fish

Squid

Carnivorous plankton

Krill

Phytoplankton

Herbivorouszooplankton

Emperorpenguin

Note: ArrowsGo in directionOf energy flow…

Food Webs and the Laws of matter and energy

Food chains/webs show how matter and energy move from one organism to another through an ecosystemEach trophic level contains a certain amount of biomass (dry weight of all organic matter)

Chemical energy stored in biomass is transferred from one trophic level to the nextWith each trophic transfer, some usable energy is degraded and lost to the environment as low quality heat • Thus, only a small portion of what is eaten and

digested is actually converted into an organisms’ bodily material or biomass (WHAT LAW ACCOUNTS FOR THIS?)

Food Webs and the Laws of matter and energy

Food chains/webs show how matter and energy move from one organism to another through an ecosystemEach trophic level contains a certain amount of biomass (dry weight of all organic matter)

Chemical energy stored in biomass is transferred from one trophic level to the nextWith each trophic transfer, some usable energy is degraded and lost to the environment as low quality heat

• Thus, only a small portion of what is eaten and digested is actually converted into an organisms’ bodily material or biomass (WHAT LAW ACCOUNTS FOR THIS?)

Ecological Efficiency:The % of usable nrg transferred as biomass from one trophic level to the next (ranges from 5-20% in most ecosystems, use 10% as a rule of thumb)Thus, the more trophic levels or steps in a food chain, the greater the cumulative loss of useable energy…

Food Webs and the Laws of matter and energy

Ecological Efficiency:The % of usable energy transferred as biomass from one trophic level to the next (ranges from 5-20% in most ecosystems, use 10% as a rule of thumb)Thus, the more trophic levels or steps in a food chain, the greater the cumulative loss of useable energy…

Pyramids of Energy and MatterPyramid of Energy FlowPyramid of Biomass

Heat

Heat

Heat

Heat

Heat

1010

100100

1,0001,000

10,00010,000Usable energyUsable energy

Available atAvailable atEach tropic levelEach tropic level(in kilocalories)(in kilocalories)

ProducersProducers(phytoplankton)(phytoplankton)

Primaryconsumers

(zooplankton)

Secondaryconsumers

(perch)

Tertiaryconsumers

(human)

Decomposers

Ecological Pyramids of Energy

Ecological Pyramids of Biomass

Implications of Pyramids….Why could the earth support more people if the eat at lower trophic levels?Why are food chains and webs rarely more than four or five trophic levels?Why do marine food webs have greater ecological efficiency and therefore more trophic levels than terrestrial ones? Why are there so few top level carnivores?Why are these species usually the first to suffer when the the ecosystems that support them are disrupted?

Ecosystem Services and Sustainability

SolarCapital

Airresources

andpurification

Climatecontrol

Recyclingvital

chemicalsRenewable

energyresources

Nonrenewableenergy

resources

Nonrenewablemineral

resourcesPotentiallyrenewable

matterresources

Biodiversityand gene

pool

Naturalpest anddiseasecontrol

Wasteremoval and

detoxification

Soilformation

andrenewal

Waterresources

andpurification

NaturalCapital

1. Use Renewable Solar Energy As Energy Source

2. Recycle the chemical nutrients needed for life

Lessons

From

Nature!

Matter Cycles

You are responsible for knowing the water, carbon, nitrogen, sulfur, and phosphorus cyclesKnow major sources and sinksKnow major flowsKnow how human activities are disrupting these cycles

Carbon Cycle

Nitrogen Cycle