Environmental Science: Toward A Sustainable Future Chapter 3

Ecosystems: How They Work

This Lesson Is About How Ecosystems Function: Transfer Energy and Nutrients Capture of sun energy transfer through

different trophic levels. Capture of essential elements of life and

transfer through different trophic levels. Nutrient cycles. Human impacts on ecosystem function.

5 Principles of Sustainability to Learn from Natural Ecosystems

(Almost) all ecosystems use sunlight as the primary energy source

Ecosystems dispose of waste and replenish nutrients by recycling all elements

The size of consumer populations are controlled such that overgrazing and other overuse does not occur

Ecosystems are resilient to disturbances and pollutants

Ecosystems require biodiversity to function indefinitely

Ecological Principles: DICE

DiversityInterrelationshipsCyclesEnergy

Biosphere II

Purpose: recreate conditions of Earth (Biosphere I) * to understand our world better* space travel

5 acres in Arizona, 4000 species,

10 humans* problem: 02 + CO2

were absorbed by concrete* ants and cockroaches took over

Recycle or Die is the take home message This means that we have a limited supply

of raw materials (formation of the earth) All matter is recycled through the

lithosphere, hydrosphere, and atmosphere. Nothing is created nothing is destroyed All stable ecosystems recycle matter and

get energy from the sun

Elements of Life

92 naturally occurring elements

Elements Found in Living OrganismsN CHOPS (macronutrients)C HOPKINS Ca Fe Mg B Mn Cu Cl Mo Zn

Top 8 elements in the earths crust (in order)O, Si, Al, Fe (iron), Ca, Na (sodium), P, MgOnly silly apes in college study past midnight.

78% Nitrogen78% Nitrogen

21% Oxygen21% Oxygen

Atmospheric Gases in Troposphere

<0.04% Carbon Dioxide<0.04% Carbon Dioxide

Organic Compounds

C-C bonds and/or C-H bonds They can be natural or synthetic

Natural: compounds that make up living systems

Synthetic: man-made compounds

Elements of Life

Organic = carbon based molecules

Example: C6H12O6, CH4

Inorganic = molecules without carbon-carbon nor carbon-hydrogen bonds

Example: NaCl, NH4, H2SO4

Match the Elements (Left) With Molecules (Right)

Nitrogen Carbon Hydrogen Oxygen Phosphorus Sulfur

Glucose Proteins Starch Fats Nucleic acids All of the above

Building blocks of living things

Fats/Lipids Phospholipids Steroids

Proteins Chains of amino

acids Muscles Enzymes

Nucleic acids Chain of

nucleotides Deoxyribonucleic

acid Ribonucleic acid

Matter and Energy Matter: anything that occupies space and

has mass. Cannot be created or destroyed. Can be changed from one form into

another. Can be recycled. Can be measured where gravity is present.

Physics Energy is measured in calories

Calorie – amount of heat needed to raise 1 gram of water 1 degree Celsius.

Kilocalorie = 1,000 calories 1st law of thermodynamics

Energy cannot be created nor destroyed, only change forms (light to chemical)

2nd law of thermodynamics Energy transformation increases disorder (entropy)

of the universe. Heat is the lowest grade of energy.

Matter and Energy Energy: anything that has the ability to

move matter, has no mass and does not occupy space. Cannot be created or destroyed. Can be changed from one form to another. Cannot be recycled. Can be measured.

Laws of Thermodynamics

First Law: (CHANGE) Energy is neither created nor destroyed but may be converted from one form to another. NO FREE LUNCHES!

Second Law: (LOSS) In any energy conversion, you will end up with less usable energy thanyou started with. YOU CAN ‘T BREAK EVEN!

Entropy

Systems will go spontaneously in one direction only which is toward increasing entropy.

Example of the Laws of Conservation of Matter and ThermodynamicsExample of the Laws of Conservation of Matter and Thermodynamics

Global WarmingGlobal Warming

Acid RainAcid Rain SmogSmog

Burning Coal = CO2 + SOx + H20 + Ash(CxHxSxOx) Light + Noise + Heat

First Principles of Ecosystem Sustainability Ecosystems use

sunlight as their source of energy.

Elements of Life

Photosynthesis

6 CO2 + 6 H20 C6H12O6 + 6 O2

Respiration

C6H12O6 + 6 O2 6 CO2 + 6 H20

Which process uses and which produces energy?Which process occur in plants and which in animals?

The First Principle of Ecosystem Sustainability At WorkThe First Principle of Ecosystem Sustainability At Work

Match Outcomes (Left) With Process (Right)Match Outcomes (Left) With Process (Right)

Releases O2 Stores energy Releases CO2 Uses CO2 Releases energy Produces sugar Uses sugar Uses O2

Photosynthesis Cell respiration Both Neither

Match Outcomes (Left) With Organisms (Right)Match Outcomes (Left) With Organisms (Right)

Releases O2 Stores energy Releases CO2 Uses CO2 Releases energy Produces sugar Uses sugar Uses O2

Plants Animals Both Neither

The Second Principle of Ecosystem Sustainability

Ecosystems dispose of wastes and replenish nutrients by recycling all elements.

The Carbon Cycle How and in what form does carbon

enter and leave the cycle? How is the role of autotrophs and

heterotrophs different and the same? What are the human impacts on the

cycle?

The Phosphorus Cycle How and in what form(s) does

phosphorus enter and leave the cycle? How is the role of autotrophs and

heterotrophs different and the same? What are the human impacts on the

cycle?

Phosphorus cycle No gas phase, only solid and liquid Man-made fertilizers contain organic

phosphates Because P is a limiting factor in aquatic

systems, it leads to eutrophication The rain forest is very good at recycling

P, except when we cut it down…

The Nitrogen Cycle How and in what form(s) does

nitrogen enter and leave the cycle? How is the role of autotrophs and

heterotrophs different and the same? What are the human impacts on the

cycle?

Nitrogen cycle Main reserve in the atmosphere Living things must get N from ammonium (NH4) or

nitrate (NO3)

N from the atmo must be fixed Change N2 into ammonium or nitrate

Rhizobium (bacteria living in roots of legumes) fig 3-10 Industrial Lightning Burning fossil fuels

The Human SystemThe Human System

The Human SystemThe Human System

Violations of the First Principle of Ecosystem Sustainability Excessive use of fossil fuels. Feeding largely on the third trophic

level. Use of coal or nuclear power. Use of agricultural land to produce

meats.

Violations of the Second Principle of Ecosystem Sustainability Lack of recycling. Excessive use of fertilizers. Destruction of tropical rain forests. Nutrient overcharge into aquatic

ecosystems. Production and use of

nonbiodegradable compounds.

Ecosystem Services and Functions

Gas, climate and water regulationGas, climate and water regulationWater supplyWater supplyErosion controlErosion controlSoil formationSoil formationPollinationPollinationBiological controlBiological control

Ecosystem Services and Functions

Food productionFood productionRecreationRecreationRaw materialsRaw materialsNutrient cyclingNutrient cyclingWaste treatmentWaste treatment