The Balance of the Living World

Ecology is the study of the distribution and interactions of living communities with each other and the abiotic habitat.

It is an objective science based on the collection of field observations and experimental data.

Environmentalism is a way of thinking that places maintaining the richness and balance of nature as a top priority.

It is a subjective belief system based on an emotional response to information provided by ecology

Biosphere Ecosystem Community Population Individual

A single of member of a species

Chimpanzee, Pan troglodytes

A group of individuals that belong to the same species, live in the same area, and breed with others in the same group.

Scalloped hammerhead, Sphyrna lewini

The many different species that live together in a given area.

A collection of populations in a habitat.

An ecological system encompassing a community and all the physical

aspects of its habitat.

The sum total of all ecosystems

autotroph Self-feeder, uses environmental energy to

create organic molecules ex. plant, algae, cyanobacteria Common name: producer

chemoautotroph Self-feeder, uses non-organic chemicals (H2S)

as energy source ex. bacteria surrounding ocean vents Common name: producer

heterotroph Other-feeder, consumes living organisms for

energy needs Ex. Insects, zooplankton, mammals, etc. Common name: consumer

saprotroph obtains energy by secreting enzymes outside

body and absorbing digested remains of once living organisms

Ex. Fungi and bacteria Common name: decomposer

The trophic level of an organism is its position in the food chain

Primary Producer The foundation of the trophic pyramid (food

chain) Primary Consumer

Heterotrophic feeders of producers Typically herbivores (eat photosynthetic

organisms) Secondary Consumer

Obtains energy from the primary consumer Typically carnivores or omnivores.

Tertiary Consumer, etc.

The collection of all the food chains in a given area

A food web describes the predator-prey relationships of a given community

It is a model of the energy flow through a living system

Very rarely does the model accurately represent the full collection of organisms

First Law of Thermodynamics: Energy can be transferred and

transformed, but it cannot be created or destroyed.

Second Law of Thermodynamics Every energy transfer or transformation

increases the entropy of the universe Ordered forms of energy are at least partly

converted to heat.

Microorganismsand other

detritivores

Tertiaryconsumers

Secondaryconsumers

Detritus Primary consumers

Sun

Primary producers

Heat

Key

Chemical cycling

Energy flow

Nutrient Cycling

Defined as the amount of light energy converted to chemicalchemical energy, i.e., the total amount of organic matter made by producers, during any given time period.

Globally, primary producers create approximately 10 billion tons of organic 10 billion tons of organic materialsmaterials per year.

Gross Primary Production (GPP) is the total primary production in an ecosystem

Net Primary Production (NPP) is the GPP minus the energy used by primary producers for respiration (R)

NPP = GPP - R

NPP represents the storage of chemical energy that will be available to consumers in the ecosystem.

NPP can be expressed as: Energy per unit area per unit time (J/m2/yr) Biomass (weight; usually dry weight) of

vegetation added per unit area per unit time (g/m2/yr)

Standing crop: total mass of photosynthetic organisms present at a given time

NPP: amount of new biomass added in a given time period

Open oceanContinental shelf

Upwelling zonesExtreme desert, rock, sand, ice

Swamp and marshLake and stream

Desert and semidesert scrubTropical rain forest

Temperate deciduous forestTemperate evergreen forest

Tropical seasonal forest

SavannaCultivated land

EstuaryAlgal beds and reefs

Boreal forest (taiga)Temperate grassland

Woodland and shrublandTundra

0.40.4

1.01.31.51.61.71.82.42.72.93.33.54.7

0.30.10.1

5.265.0

Freshwater (on continents)

TerrestrialMarine

Key Percentage of Earth’ssurface area

Average net primaryproduction (g/m2/yr)

6050403020100 2,5002,0001,5001,0005000

Percentage of Earth’snet primary production

2520151050

125

2,500

3601,500

5003.090

900600

800

2,200

600

250

1,6001,2001,300

2,000

700140

0.3

7.99.19.6

5.43.5

0.67.1

4.93.8

2.3

24.45.6

1.20.9

0.10.040.9

22

North Pole

60°N

30°N

South Pole

Equator

60°S

30°S

60°W 60°E 120°E120°W180° 0° 180°

High R O Y G B I V Low

How much energy is passed to the next level of a food chain relative to what is available.

Energy transfer between trophic levels is usually < 20% efficient

Defined as: amount of chemical energy in consumer’s food that is converted to their own biomass during a given time period

How much mass is gained compared to how much food is eaten.

NET SECONDARY NET SECONDARY PRODUCTION = PRODUCTION = 33J33J

Growth (new biomass)

Cellularrespiration

Feces100 J

33 J

67 J

200 J

Plant materialeaten by caterpillar

Production Efficiency = Net Secondary Production Assimilation of Primary Production

33J100J = 33%

Note that energy lost as undigestible material does not count toward assimilation.

Growth (new biomass)

CellularrespirationFeces

100 J33 J

67 J

200 J

Plant materialeaten by caterpillar

The percentage of food intake (energy) that is converted to new biomass

Birds & Mammals (endotherms) ~ 1-3%

Fish ~ 10% Insects ~ 40%

• Trophic Efficiency = Y/X x 100• Usually ranges from 10% – 20%.• i.e., 80% – 90% energy available at one trophic level is not transferred to the next trophic level.• This loss is multiplied over the length of the food chain.

1,000,000 J of sunlight

10,000 J

1,000 J

100 J

10 JTertiaryconsumers

Secondaryconsumers

Primaryconsumers

Primaryproducers

Size of each block is proportional to the net production, expressed in energy units.

Trophic level Dry weight(g/m2)

Tertiary consumers

Secondary consumers

Primary consumers

Primary producers

1.5

11

37

809

Most biomass pyramids show a sharp decrease in biomass at successively higher trophic levels, as illustrated by data from a bog at Silver Springs, Florida.

Size of each block is proportional to the standing crop (total dry weight of all organisms) at each trophic level.

Carbon, Nitrogen, Potassium, Water, Phosphorous

Energy is used to maintain highly ordered homeostasis with organisms

Basic materials of living organisms: Carbon Nitrogen Oxygen Phosphorus

CO2 + H2O C6H12O6 + O2

sunlight

Only occurs in autotrophs (animals that make their own food)

CO2 + H2O + ATPC6H12O6 + O2

Happens in all eukaryotic cells (everything but bacteria)Yes, that means both animals and plants

sugar

Carbon Dioxide required for photosynthesis Plants take CO2 from the air. Carbon can be found…

1. in atmosphere, 2. dissolved in water, 3. in living organisms,4. or deposited at CaCO3 (limestone) or fossil fuels

Decomposition, combustion, and respiration returns C to atmosphere as CO2

Atmospheric and Ocean CO2

Plants Animals

Fossil Fuels

photosynthesis

respirationcombustion

Limestone(plankton)

erosion

N is a major component of proteins, the basic functional unit of the cell.

Most N is found in atmosphere as N2

Only a few bacteria can use N2 and turn it into forms of N that plants can use.

Animals get their N from the food they eat.

Other bacteria turn organic N from urea and dead organisms back into N2

N2 (79% of atmosphere)

Animals PlantsUrea Death Bacteri

a, soil

Bacteria

Bacteria

N2

NH3NO3

N2

NH3

NO3