Ecosystem Organization Organism = a living thing Population = a group of organisms living in the same area Community = a group of species that live in the same habitat and interact with each other Ecosystem= a community of organisms and their abiotic environment

Three hundred trout are needed to support one man for a year. The trout, in turn, must consume 90,000 frogs, that must consume 27 million grasshoppers that live off of 1,000 tons of grass. -- G. Tyler Miller, Jr., American Chemist (1971)

Biotic vs Abiotic Biotic: Living component of a community Abiotic: Non living component of a community

All Organisms Need ENERGY! All life on earth depends on the sun.

Energy Transfer Each time an organism eats another organism, an energy transfer takes place. Trophic level= each step through which energy is transferred in a food chain. Represented in food chains & webs

As energy passes between trophic levels… Only a fraction of the energy available is transferred to the next level (approximately 10%). The numbers and biomass of organisms decrease as you move up a food chain.

1 st Law of Thermodynamics Energy cannot be created or destroyed; it is only changed from one form to another. Ex: Solar energy  chemical energy in plants

2 nd Law of Thermodynamics Whenever energy is transformed, there is a loss of energy through the release of heat.

Controlling Ecosystem Function… “Bottom-Up Control” = it is the nutrient supply to the primary producers that ultimately controls how ecosystems function. “Top-down Control” = predation and grazing by higher trophic levels ultimately controls ecosystem function.

Ecosystem 1. Tropical rainforest 2. Sahara desert 3. US desert 4. Temperate forest (Pennsylvania) 5. Tundra 6. Pacific Ocean 7. North Atlantic Ocean 8. Pond Ecosystem 9. Savanna 10. Wetlands (Everglades) 11. Coral Reef 12. Prairie 13. Caribbean Ocean

Species Relationships Predation Symbiosis Mutualism Commensalism Parasitism

RelationshipDefinitionExample PREDATIONOne organism kills and eats another organism for food. SYMBIOSISTwo organisms interact over a long period of time. MutualismType of symbiosis; both organisms benefit. (+/+) CommensalismType of symbiosis; one organism benefits, the other is unaffected. (+/0) ParasitismType of symbiosis; one species benefits while the other is harmed. (+/-)

Nitrogen Cycle N is needed as a component of DNA and proteins. Problem with atmospheric nitrogen: most organisms cannot use atmospheric N.

Nitrogen Fixation N 2 (atmospheric) is converted to ammonium (NH 4 + ) By bacteria Lightning

Nitrogen Uptake Fixed nitrogen is incorporated into compounds by plants. Moves up through the food chain!

Decay Decomposers change nitrogen from dead organisms into ammonium (NH 4 + ) Available for use by plants

Nitrification Some ammonium is converted into nitrate (NO 3 - ) by bacteria Ammonium: + charge  stick to – charged soil particles and cannot be washed away. Nitrate: – charge  does NOT stick and is easily washed away

Denitrification Nitrate is converted to N 2 by bacteria Removes nitrogen from ecosystems Balances amount of nitrogen fixed

Geological Carbon Cycle CO 2 + H 2 0  carbonic acid Minerals on earth’s surface dissolve, make sediment. Sediment forms limestone. As it is pushed deeper below earth’s surface, it heats up, melts and returns to surface as CO =related

Carbon Cycle C is necessary for structure and energy. Carbon source vs. carbon sink Carbon source: when more C leaves than enters. Carbon sink: when more C enters than leaves.

Biological Carbon Cycle Photosynthesis: Plants use CO 2, solar energy to make sugars. Respiration: Releases energy from sugars, releases CO 2. Remains of some organisms can be buried and form deposits of coal and oil.

Phosphorus Cycle The phosphorus cycle is the movement of phosphorus from the environment to organisms and then back to the environment. Slow process Does not include the atmosphere because phosphorus rarely occurs as a gas Phosphorus is an integral element and is required for molecules that make up cells or living things.

Phosphorus Cycle