How Ecosystems Work Honors Biology PFHS Chapter 5

Energy Flow in an open system Life depends on the sun (energy source) Life depends on the sun (energy source) Energy captured by photosynthesis Energy captured by photosynthesis This energy is used by organisms to move, grow, and reproduce This energy is used by organisms to move, grow, and reproduce Energy is constantly coming in and going out of the earth system Energy is constantly coming in and going out of the earth system

Niches Jobs, occupations, or roles in the ecosystem Examples: producer (autotroph), consumer (heterotroph), decomposer

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

Niches Consumer – obtains nutrient molecules by eating another organism Consumer – obtains nutrient molecules by eating another organism 1 st order – herbivore; eats photosynthetic plants 1 st order – herbivore; eats photosynthetic plants 2 nd order – carnivore; eats flesh of herbivore 2 nd order – carnivore; eats flesh of herbivore Tertiary – carnivore/omnivore; eats flesh of carnivore/omnivore Tertiary – carnivore/omnivore; eats flesh of carnivore/omnivore Omnivore – eats both plant and animal material Omnivore – eats both plant and animal material

Niches Saprovore – eats dead/decaying material Saprovore – eats dead/decaying material Scavenger – roadkill specialist Scavenger – roadkill specialist Decomposer – breaks down dead material to energy and recycles matter to the environment Decomposer – breaks down dead material to energy and recycles matter to the environment

Burning the Fuel Cellular respiration – 90% of energy obtained is used for daily activity; 10% available for next trophic level Cellular respiration – 90% of energy obtained is used for daily activity; 10% available for next trophic level C 6 HO + 6O > 6CO 2 + 6H energy (heat and ATP) C 6 H 12 O 6 + 6O > 6CO 2 + 6H energy (heat and ATP)

Energy Transfer

Recycling of Matter in a Closed System Closed system means a finite supply of matter; unlike infinite supply of energy Closed system means a finite supply of matter; unlike infinite supply of energy Material must be used over and over Material must be used over and over Earth system has many biogeochemical cycles Earth system has many biogeochemical cycles

Carbon Cycle

Nitrogen Cycle

Phosphorus Cycle

Hydrologic Cycle

Ecological 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……..?

And……..

And……..

Example – Surtsey Island, Iceland

Diagram of bog succession.

Primary Succession No soil No soil Pioneer species take hold, break down rock and contribute organic material = soil Pioneer species take hold, break down rock and contribute organic material = soil Grasses, shrubs, then trees after soils Grasses, shrubs, then trees after soils Climax community Climax community –May vary –Depends on environment

Secondary Succession

After…………..

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 1 Whale dies and sinks to floor Whale dies and sinks to floor Scavengers/decomposers Scavengers/decomposers

Marine Succession 2 Smaller # of organisms Smaller # of organisms Sediment dwellers with enrichment of sediments from decomposition Sediment dwellers with enrichment of sediments from decomposition

Marine Succession 3 Skeleton remains Skeleton remains Heterotrophic bacteria decompose oils in bones Heterotrophic bacteria decompose oils in bones Release chemicals for chemosynthetic bacteria Release chemicals for chemosynthetic bacteria Bacteria support mussels, limpets, snails, worms, crabs, clams, sediment dwellers around remaining bones Bacteria support mussels, limpets, snails, worms, crabs, clams, sediment dwellers around remaining bones

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

Changes in soil nitrogen and phosphorus.

“Greenhouse Effect” Solar energy passes mostly unimpeded through the atmosphere and is absorbed at the surface Solar energy passes mostly unimpeded through the atmosphere and is absorbed at the surface Outgoing long-wave radiation off the surface is absorbed by the atmosphere Outgoing long-wave radiation off the surface is absorbed by the atmosphere A portion of the absorbed long-wave radiation is sent back down to the surface A portion of the absorbed long-wave radiation is sent back down to the surface The surface has a temperature 30˚ C warmer than it normally would have The surface has a temperature 30˚ C warmer than it normally would have This process is termed the “greenhouse effect” This process is termed the “greenhouse effect”

“Greenhouse”?! Greenhouses are certainly warm places on sunny days Greenhouses are certainly warm places on sunny days However, greenhouses are not warm because of the trapping of infrared radiation However, greenhouses are not warm because of the trapping of infrared radiation A greenhouse is warm because convection is inhibited by the glass (the warm air is stuck inside the greenhouse) A greenhouse is warm because convection is inhibited by the glass (the warm air is stuck inside the greenhouse) Therefore, the term “greenhouse effect” is a misnomer and does not apply to the atmosphere Therefore, the term “greenhouse effect” is a misnomer and does not apply to the atmosphere

Greenhouse Effect vs. Global Warming The “greenhouse effect” is a good thing, otherwise we would be an ice planet The “greenhouse effect” is a good thing, otherwise we would be an ice planet The terms “greenhouse effect” and “global warming” do not mean the same thing The terms “greenhouse effect” and “global warming” do not mean the same thing Global warming is the concern that, by increasing the gases that trap infrared radiation in our atmosphere, we will increase the average surface temperature of the Earth Global warming is the concern that, by increasing the gases that trap infrared radiation in our atmosphere, we will increase the average surface temperature of the Earth