Ecology: the study of interactions of organisms and their physical environment.

Community: organisms that live in a particular place.

Habitat: physical location of community.

Ecosystem: self-sustaining collection of organisms and their physical environments.

Diversity of ecosystem: measure of number of species living in ecosystem and how common each species is.

Stability: the ability of an ecosystem to resist change in the face of disturbances.

Energy in ecosystems

Producers: take in energy, store in complex molecules. include plants, algae, and some bacteria.

Consumers: all other organisms which obtain energy by consuming other organisms.

Decomposers: special consumers that obtain energy by consuming organic wastes, dead bodies. includes fungi and some bacteria.

 Energy flow

Trophic Levels: a group of organisms whose energy sources are the same number of steps away from the sun.

1st trophic level: producers (autotrophs).

2nd trophic level: animals that eat plants (herbivores). primary consumers.

3rd trophic level: animals that eat herbivores (carnivores). secondary consumers.

4th trophic level: animals that feed on carnivores. tertiary consumers. all ecosystems must contain decomposers (detritivores)!!

Food Web: a complex network of feeding relationships in an ecosystem.

Food chain: Path of energy through trophic levels.

 Nutrient cycles

Nitrogen Cycle: nitrogen is necessary to make proteins and nucleic acids.

1. nitrogen fixation by bacteria breaks bonds and allows nitrogen atoms to react with hydrogen atoms to form ammonia.

2. assimilation: plants absorb ammonia and incorporate it into their compounds.

 Water Cycle

1. Non-living cycle: water vapor in atmosphere condenses, falls to the earth's surface as precipitation. seeps into soil and becomes ground water. remaining water is heated by the sun to reenter the atmosphere by evaporation.

2. Living cycle: taken up by plant roots, moves into the atmosphere by transpiration Carbon Cycle: carbon dioxide in air is used by plants during photosynthesis. consumers break down carbon compounds by cellular respiration, and release carbon dioxide into the atmosphere as carbon dioxide.

Phosphorous Cycle: phosphorus is needed in ATP and DNA. usually found in soil and rocks, which dissolves in water to form phosphate ions. phosphorus can lead to algal blooms which kills other organisms in the lake when bacteria, which feed on the dead algae, use up dissolved oxygen in the water.

Interactions within ecosystems

Coevolution: two or more species evolve in response to each other.

Predation: one organism feeds on another.

Symbiosis: close long-term relationship between two or more species.

1. Parasitism: obtain nutrients by feeding on living host, usually harming but not killing it.

2. Mutualism: both participants benefit.

Niche: sum of organism's interactions with its physical environment and with other organisms.

Competition: the use or defense of a resource by one individual that reduces the availability of that resource to other individuals.

1. intraspecific competition: between members of the same species.

2. interspecific competition: between different species.

Succession: gradual sequential replacement of populations in an area.

Pioneer species: the first to colonize a new habitat.

Seral community: each of the intermediate communities that arise through the process of succession.

Climax community: one that will remain stable as long as the area is undisturbed.

Primary succession: occurs in areas where nothing has ever grown before.

Secondary succession: areas where there has been previous growth. habitats were disturbed, but not totally stripped of vegetation and soil.

Succession in lakes: lakes that change from crystal clear bodies of water to dry land when the lake becomes filled in with sediment.

Eutrophication: process of adding large amounts of nutrients to the water.

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