How Ecosystems WorkHow Ecosystems Work

Honors BiologyHonors Biology

PFHSPFHS

Chapter 5Chapter 5

Energy Flow in an open Energy Flow in an open systemsystem

• Life depends on the sun (energy Life depends on the sun (energy source)source)

• Energy captured by photosynthesisEnergy captured by photosynthesis

• This energy is used by organisms to This energy is used by organisms to move, grow, and reproducemove, grow, and reproduce

• Energy is constantly coming in and Energy is constantly coming in and going out of the earth systemgoing out of the earth system

NichesNiches

Jobs, occupations, or roles in Jobs, occupations, or roles in the ecosystemthe ecosystem

Examples: producer Examples: producer (autotroph), consumer (autotroph), consumer

(heterotroph), decomposer(heterotroph), decomposer

NichesNiches

• Producer (autotroph) makes nutrient Producer (autotroph) makes nutrient molecules from molecules from photo-/chemosynthesisphoto-/chemosynthesis

NichesNiches• Consumer – obtains nutrient Consumer – obtains nutrient

molecules by eating another organismmolecules by eating another organism• 11stst order – herbivore; eats order – herbivore; eats

photosynthetic plantsphotosynthetic plants• 22ndnd order – carnivore; eats flesh of order – carnivore; eats flesh of

herbivoreherbivore• Tertiary – carnivore/omnivore; eats Tertiary – carnivore/omnivore; eats

flesh of carnivore/omnivoreflesh of carnivore/omnivore• Omnivore – eats both plant and Omnivore – eats both plant and

animal materialanimal material

NichesNiches• Saprovore – eats dead/decaying Saprovore – eats dead/decaying

materialmaterial

• Scavenger – roadkill specialistScavenger – roadkill specialist

• Decomposer – breaks down dead Decomposer – breaks down dead material to energy and recycles material to energy and recycles matter to the environmentmatter to the environment

Burning the FuelBurning the Fuel• Cellular respiration – 90% of energy Cellular respiration – 90% of energy

obtained is used for daily activity; obtained is used for daily activity; 10% available for next trophic level10% available for next trophic level

• CC66HH12OO6 + 6O + 6O22 -----> 6CO -----> 6CO22 + 6H + 6H220 + 0 + energy (heat and ATP)energy (heat and ATP)

Energy TransferEnergy Transfer

Recycling of Matter in a Closed Recycling of Matter in a Closed SystemSystem

• Closed system means a finite supply Closed system means a finite supply of matter; unlike infinite supply of of matter; unlike infinite supply of energyenergy

• Material must be used over and overMaterial must be used over and over

• Earth system has many Earth system has many biogeochemical cyclesbiogeochemical cycles

Carbon CycleCarbon Cycle

Nitrogen CycleNitrogen Cycle

Phosphorus CyclePhosphorus Cycle

Hydrologic CycleHydrologic Cycle

Ecological SuccessionEcological Succession

Succession Defined:

• The sequential change in the relative abundances of the dominant species in a biological community following a disturbance.

• Primary succession: beginning from a abiotic environment following a cataclysmic disturbance.

• Secondary succession: beginning from a major disturbance, but all forms of life are not destroyed.

Primary Succession

After……..?After……..?

And……..And……..

And……..And……..

Example – Surtsey Island, Example – Surtsey Island, IcelandIceland

Diagram of bog Diagram of bog succession.succession.

Primary SuccessionPrimary Succession

• No soilNo soil

• Pioneer species take hold, break down Pioneer species take hold, break down rock and contribute organic material = rock and contribute organic material = soilsoil

• Grasses, shrubs, then trees after soilsGrasses, shrubs, then trees after soils

• Climax communityClimax community– May varyMay vary– Depends on environmentDepends on environment

Secondary SuccessionSecondary Succession

After…………..After…………..

Or…………Or…………

Stages of Succession• Early: plants typically small with short

lifecycles (annuals…), rapid seed dispersal, environmental stabilizers.

• Middle: plants typically longer lived, slower seed dispersal, and in woodland systems: larger.

• Late: plants and animal species are those associated with older, more mature ecosystem.

• “Climax”?

Marine Succession 1Marine Succession 1

• Whale dies and sinks to floorWhale dies and sinks to floor

• Scavengers/decomposersScavengers/decomposers

Marine Succession 2Marine Succession 2

• Smaller # of organismsSmaller # of organisms

• Sediment dwellers with enrichment Sediment dwellers with enrichment of sediments from decompositionof sediments from decomposition

Marine Succession 3Marine Succession 3

• Skeleton remainsSkeleton remains• Heterotrophic bacteria decompose oils Heterotrophic bacteria decompose oils

in bonesin bones• Release chemicals for chemosynthetic Release chemicals for chemosynthetic

bacteriabacteria• Bacteria support mussels, limpets, Bacteria support mussels, limpets,

snails, worms, crabs, clams, sediment snails, worms, crabs, clams, sediment dwellers around remaining bonesdwellers around remaining bones

Fig 10.8 Graphs Fig 10.8 Graphs showing changes showing changes in biomass and in biomass and diversity with diversity with succession.succession.

Changes in soil Changes in soil nitrogen and nitrogen and phosphorus.phosphorus.

““Greenhouse Effect”Greenhouse Effect”

• Solar energy passes mostly unimpeded Solar energy passes mostly unimpeded through the atmosphere and is absorbed at the through the atmosphere and is absorbed at the surfacesurface

• Outgoing long-wave radiation off the surface is Outgoing long-wave radiation off the surface is absorbed by the atmosphereabsorbed by the atmosphere

• A portion of the absorbed long-wave radiation A portion of the absorbed long-wave radiation is sent back down to the surfaceis sent back down to the surface

• The surface has a temperature 30˚ C warmer The surface has a temperature 30˚ C warmer than it normally would havethan it normally would have

• This process is termed the “greenhouse effect”This process is termed the “greenhouse effect”

““Greenhouse”?!Greenhouse”?!

• Greenhouses are certainly warm places on Greenhouses are certainly warm places on sunny dayssunny days

• However, greenhouses are not warm However, greenhouses are not warm because of the trapping of infrared radiationbecause of the trapping of infrared radiation

• A greenhouse is warm because convection A greenhouse is warm because convection is inhibited by the glass (the warm air is is inhibited by the glass (the warm air is stuck inside the greenhouse)stuck inside the greenhouse)

• Therefore, the term “greenhouse effect” is Therefore, the term “greenhouse effect” is a misnomer and does not apply to the a misnomer and does not apply to the atmosphereatmosphere

Greenhouse Effect vs. Global Greenhouse Effect vs. Global WarmingWarming

• The “greenhouse effect” is a good thing, The “greenhouse effect” is a good thing, otherwise we would be an ice planetotherwise we would be an ice planet

• The terms “greenhouse effect” and “global The terms “greenhouse effect” and “global warming” do not mean the same thingwarming” do not mean the same thing

• Global warming is the concern that, by Global warming is the concern that, by increasing the gases that trap infrared increasing the gases that trap infrared radiation in our atmosphere, we will radiation in our atmosphere, we will increase the average surface temperature increase the average surface temperature of the Earth of the Earth