Ecology the study of organisms and their relationship

Ecology

• the study of organisms and their relationship to the environment and each other

Ecosystem Components • Biotic Components (living factors) • Plants • Decomposers (Bacteria, Fungi) • Animals • Abiotic Components (nonliving factors) • Water • Atmosphere (temperature, p. H, O 2, CO 2) • Soil

Basic Terms

Population • A POPULATION is all of the individuals of a single species that live within a certain area

Community • A community is all of the populations of different organisms within a given area

Ecosystem • The ecosystem is the collection of all the organisms that live in a particular place together with the abiotic limiting factors

Biome • A BIOME is a group of ecosystems that have the same climate and are characterized by specific plants and animals

Biosphere • portions of the planet where life can exist (land, water, lower atmosphere)

Energy Flow Relationships • What is the source of energy for all living things?

• The sun is the source of energy for all photosynthetic autotrophs

• Some autotrophs are chemosynthetic • They can use chemicals like sulfer to obtain the energy to make organic molecules • Ex) bacteria near deep sea volcanic vents

Food chains show the flow of energy from the sun through producers and consumers in an ecosystem

• Producers an autotroph that synthesizes new organic molecules by photosynthesis or chemosynthesis – Autotrophs are ALWAYS the bottom of a food chain

• Consumers organisms that eat plants and/or other animals – Primary consumer eats plants – Secondary consumer eats primary consumer – Tertiary consumer eats the secondary consumer

Herbivores • Consumers that eat the producers (autotrophs)

carnivores • Consumers that eat other consumers – Predator – kills its food – Scavenger – eats dead animals

Omnivore • Consumers that eat BOTH autotrophs and other consumers

Decomposers • Bacteria, some worms and fungi that break down dead organic material and return the nutrients to the soil

Important Concepts • Energy flow through an ecosystem is shown with arrows in a food chain or food web.

• Nutritional relationships are never as simple as a food chain • A FOOD WEB is a diagram that shows overlapping food chains – Organisms eat more than one thing – Organisms are eaten by more than one thing

• Most energy is stored in the producers and the producers should be the most abundant organism in any food chain or food web.

• An ecosystem is self-sustaining if: a) there is a constant source of energy (sun, chemicals) b) there is a continuous cycle of materials (decomposers recycle organic material back into the environment)

Food pyramid relationships Diagrams showing how certain factors change within a food chain

Pyramid of energy • Measures the potential energy in the molecules of organisms at each level of the pyramid • The 10% rule – only 10% of energy passes from one step to the next • Organisms are using the energy for their own life functions (metabolism)

Pyramid of biomass • Measures the quantity or organic material present at one time in an environment • In which level is MOST of the organic material found in an environment? • WHY?

Pyramid of numbers • Measures the total number of organisms that occupy each level • The largest number of organisms are the producers • WHY are there fewer tertiary consumers than secondary consumers?

Biological magnification • The accumulation of toxic substances in higher levels of a food chain • These are mainly substances that are not easily excreted by animals – Example) the herbicide DDT

Nutrient recycling • Different organisms chemically transform molecules containing important elements which makes them available to other organisms

The water cycle

The carbon cycle

The nitrogen cycle

• Plant and animal wastes decompose, adding nitrogen to the soil in the form of NH 4. – This is called ammonification • .

• Bacteria in the soil convert these forms of nitrogen into forms plants can use. • Plants absorb the nitrates in the soil to use for protein and nucleic acid synthesis. – This is called assimilation

• People and animals eat the plants; then animal and plant residues return nitrogen to the soil again, completing the cycle.

Soil bacteria that assist in the nitrogen cycle include • Nitrifying bacteria convert ammonia to nitrate (NO 3 -1) which is a form of nitrogen the plants can use

• Nitrogen fixing bacteria convert atmospheric nitrogen gas (N 2) to nitrates

• Denitrifying bacteria convert excess nitrates in soil to N 2 gas which enters the atmosphere

Ecological succession • As organisms live in a given area their activities can alter the environment • The altered environment may be better suited to a newer, more complex, group of organisms

Primary succession • The environment begins as a bare rock surface • The first organisms are the pioneer organisms

• Most often the pioneer organism is Lichens – Lichens are algae and fungus living in a mutualistic symbiotic relationship

• Metabolic wastes produced by the lichens help break the rock into smaller pieces • Dead lichens decompose and the molecules mix with pieces of rock to form soil

• Tiny plants like mosses grow and replace the lichens • Mosses help to create better soil

• Larger plants can survive once the soil is suitable • Lichens mosses grasses shrubs trees

• As larger plants grow, a wider variety of animals can survive in the area

Climax community • A mature, stable community that is difficult to change

Secondary succession • This type of succession occurs in areas in which the climax community has been destroyed by a catastrophe – Ex) Fire, flood, earthquake, landslide

• This area will end in the same climax community because: • The area has existing soil • The climate of the community has not changed

Pond succession • Lakes and ponds also pass through stages of ecological succession • This begins when sediment, fallen leaves and other debris gradually accumulate on the lake bottom

• As the lake fills in it becomes rich in nutrients that can support a large population of organisms