Ecosystems and Human Ecosystems and Human InterferencesInterferences

Chapter 48Chapter 48

OutlineOutline Biotic ComponentsBiotic Components

AutotrophsAutotrophs HeterotrophsHeterotrophs

Energy FlowEnergy Flow Laws of ThermodynamicsLaws of Thermodynamics Ecological PyramidsEcological Pyramids

Biogeochemical CyclesBiogeochemical Cycles Hydrologic CycleHydrologic Cycle Carbon CycleCarbon Cycle Nitrogen CycleNitrogen Cycle Phosphorus CyclePhosphorus Cycle

Biotic ComponentsBiotic Components AutotrophsAutotrophs

Require only inorganic Require only inorganic nutrients (EX?) and an outside nutrients (EX?) and an outside energy source (EX?) to produce energy source (EX?) to produce organic nutrients.organic nutrients.

Examples of autotrophs?Examples of autotrophs?

HeterotrophsHeterotrophs

HeterotrophsHeterotrophs need a preformed need a preformed source of organic nutrients.source of organic nutrients. ConsumersConsumers

Herbivores EX?Herbivores EX?Carnivores EX?Carnivores EX?Omnivores EX?Omnivores EX?

DecomposersDecomposers EX? EX?

Biotic ComponentsBiotic Components

Abiotic Components: Abiotic Components: Energy And MatterEnergy And Matter

Energy---Flows Energy---Flows through through an an ecosystemecosystemWHY?WHY?

Matter—Cycles Matter—Cycles withinwithin an an ecosystemecosystemEXAMPLES?EXAMPLES?

DefinitionsDefinitions EnergyEnergy

PotentialPotential KineticKinetic ChemicalChemical Matter and energy are interconvertible.Matter and energy are interconvertible.

WorkWork Spontaneous change vs non-Spontaneous change vs non-

spontaneous changespontaneous change Do characteristics of life require work?Do characteristics of life require work?

Types of Energy in Biological Systems• Kinetic energy - energy of motion, work done

• Potential energy - stored energy, can be released to do work

• Archer draws bowstring back - used kinetic energy

• Tension now in bowstring represents potential energy

• Release of bowstring converts potential energy to kinetic energy

Energy (cont’d)Energy (cont’d)

ThermodynamicsThermodynamics a a system:system:

Some portion of the universe that you wish to studySome portion of the universe that you wish to study

The The surroundings:surroundings:The adjacent part of the universe outside the system, i.e. The adjacent part of the universe outside the system, i.e.

everything but the systemeverything but the system

NOTE: Changes in a system are associated NOTE: Changes in a system are associated with the transfer of energywith the transfer of energy

Natural systems tend toward states of minimum energyNatural systems tend toward states of minimum energy

1st Law of 1st Law of ThermodynamicsThermodynamics

Total Energy in Universe is Constant energy cannot be created or

destroyed Energy can be converted from one

form to another The pathway of conversion is irrelevant,

the energy change between identical initial and final states is equal

When it comes to energy-You can’t get ahead!

2nd Law of 2nd Law of Thermodynamics-You can’t Thermodynamics-You can’t

break even, either!break even, either! No conversion is 100% efficient. Total useful energy in a closed system

decreases as conversions occur. Closed systems go from complex to simple. Entropy

Measure of Disorder Closed systems tend to their highest state of

disorder Entropy of the universe increases with every

conversion

2nd Law of 2nd Law of ThermodynamicsThermodynamics

Randomness is spontaneous in a closed system

• Beaker on left has different colored marbles separated from each other

• Highly ordered system

• Low entropy

Examples of Entropy

low entropy high entropy

• Beaker on right has different colored marbles scattered amongst each other

• Highly disordered system

• High entropy Other examples?

SUMMARY-SUMMARY-THERMODYNAMICSTHERMODYNAMICS

First LawFirst Law: Energy cannot be : Energy cannot be created or destroyed, but it can be created or destroyed, but it can be changed from one form to another.changed from one form to another.

Second LawSecond Law: Energy cannot be : Energy cannot be changed from one form to another changed from one form to another without loss of usable energywithout loss of usable energy

ThermodynamicsThermodynamics The SystemThe System

OpenOpen ClosedClosed

System+Surroundings=UniverseSystem+Surroundings=Universe First Law—You Can’t WinFirst Law—You Can’t Win

Ways to State?Ways to State? Second Law—You Can’t Break Even Second Law—You Can’t Break Even

EitherEither Ways to State? Examples?Ways to State? Examples?

Energy Balances and Energy Balances and ThermoodynamicsThermoodynamics

Energy FlowEnergy Flow

Food WebFood Web - Interconnecting paths of - Interconnecting paths of energy flow describing trophic energy flow describing trophic relationships.relationships.

Ecological PyramidsEcological Pyramids

A A trophic leveltrophic level is composed of all is composed of all the organisms that feed at a the organisms that feed at a particular link in a food chain.particular link in a food chain.

Pyramid of BiomassPyramid of Biomass Pyramid of NumbersPyramid of Numbers Pyramid of EnergyPyramid of Energy

10% Rule10% Rule

Ecological PyramidEcological Pyramid

Chemical CyclingChemical Cycling

Chemicals cycle as organic Chemicals cycle as organic nutrients are returned to the nutrients are returned to the producers.producers. ExcretionExcretion DeathDeath Cellular RespirationCellular Respiration

Global Biogeochemical Global Biogeochemical CyclesCycles

Chemical cycling may involve:ReservoirExchange Pool Biotic Community

When exploring chemical cycles, evaluate the human impact on that cycle

Hydrologic CycleHydrologic Cycle

Fresh water evaporates from bodies Fresh water evaporates from bodies of water.of water.

Precipitation on land enters the Precipitation on land enters the ground, surface waters, or aquifers.ground, surface waters, or aquifers.

Water eventually returns to the Water eventually returns to the oceans.oceans.

Hydrologic CycleHydrologic Cycle

Carbon CycleCarbon Cycle

Exchange pool?Exchange pool? Reservoir?Reservoir? Biotic community: How Biotic community: How

does carbon enter the does carbon enter the biotic community?biotic community?

Circle of LifeCircle of Life

Carbon compounds, O2

CO2, H2O

Respiration

Photosynthesis

Energy

Energy

Carbon CycleCarbon Cycle

Greenhouse EffectGreenhouse Effect

Greenhouse gasesGreenhouse gases allow solar radiation allow solar radiation to pass through atmosphere but trap to pass through atmosphere but trap heat (infrared radiation) from escaping.heat (infrared radiation) from escaping. Carbon dioxide, nitrous oxide, methane, HCarbon dioxide, nitrous oxide, methane, H22OO If Earth’s temperature rises, more water will If Earth’s temperature rises, more water will

evaporate, forming more clouds and setting evaporate, forming more clouds and setting up a potential positive feedback loop.up a potential positive feedback loop.

Earth’s Radiation BalancesEarth’s Radiation Balances

Nitrogen CycleNitrogen Cycle

Atmospheric nitrogen is fixed by Atmospheric nitrogen is fixed by bacteria in order to make it available bacteria in order to make it available to plants.to plants. Nodules on legume roots Nodules on legume roots

(Rhizobium/legume symbiosis).(Rhizobium/legume symbiosis). NitrificationNitrification - Production of nitrates. - Production of nitrates. DenitrificationDenitrification - Conversion of nitrate - Conversion of nitrate

to nitrous oxide and nitrogen gas.to nitrous oxide and nitrogen gas. Balances nitrogen fixation.Balances nitrogen fixation.

The Nitrogen CycleThe Nitrogen Cycle

Nitrogen and Air PollutionNitrogen and Air Pollution

Acid DepositionAcid Deposition Nitrogen oxides and sulfur dioxide are Nitrogen oxides and sulfur dioxide are

converted to acids when they combine converted to acids when they combine with water vapor.with water vapor.

Thermal InversionThermal Inversion

Phosphorus CyclePhosphorus Cycle

Phosphorus does not enter the Phosphorus does not enter the atmosphere.atmosphere. Sedimentary cycle.Sedimentary cycle.

Phosphate taken up by producers Phosphate taken up by producers incorporated into a variety of organic incorporated into a variety of organic molecules.molecules.

Can lead to water eutrophication.Can lead to water eutrophication. BiomagnificationBiomagnification

Phosphorus CyclePhosphorus Cycle

Sources of Water PollutionSources of Water Pollution

ReviewReview Biotic ComponentsBiotic Components

AutotrophsAutotrophs HeterotrophsHeterotrophs

Energy FlowEnergy Flow Ecological PyramidsEcological Pyramids

Biogeochemical CyclesBiogeochemical Cycles Hydrologic CycleHydrologic Cycle Carbon CycleCarbon Cycle Nitrogen CycleNitrogen Cycle Phosphorus CyclePhosphorus Cycle

Energy BalancesEnergy Balances