I. Introduction to Ecology

A. Organization of the Biosphere-Earth’s life

supporting layer of air, soil and water.

1. Ecosystem- A physically distinct, self- supporting unit of interacting organisms and their surrounding environment.

a) Ecosystems vary greatly in composition and size

b) Ecosystems consist of two environmental factors

1) Biotic Factors- All living things in an ecosystem: producers, consumers and decomposers

2) Abiotic Factors- nonliving parts of an ecosystem: light soil, water, wind temperature and nutrients

2. Communities and Populations

a) Community- a group of organisms that coexist in an ecosystem and form a system of production, consumption

and decomposition

b) Population- many individuals of a single species that share a common area and resources

3. Habitats and Niches

a) Habitat- surroundings in which a particular species can be found

b) Niche- way of life a species pursues within its habitat

B. Flow of Matter in the Ecosystem

• Recycling- continuous movement of chemicals throughout the ecosystem

• Biochemical cycle- pathway through which a chemical substance is recycled

3. The Water Cycle

4. Carbon Cycle

5. Nitrogen Cycle

3. Nitrogen Cycle

A) 78% of the air is nitrogen gas; however, it is useless to living organisms.

B) Most living organisms use nitrogen on in the form of nitrates (NO3-), nitrites (NO2-), ammonia (NH3).

C) Nitrogen Fixing- converting nitrogen gas to nitrates

D) Ammonification- converting nitrogen compounds to ammonia and thin is is converted into nitrates

in a process called nitrification

C. The Transfer of Energy

1. Trophic LevelsA) Producers- autotrophic plants

B) Consumers- heterotrophic animals1) 1ST order consumers are herbivores- they eat only plants.2) 2nd order consumers are carnivores- they eat other animals3) Some consumers are omnivores- they eat both plants and

animals

C) Scavenger- animals that feed off dead organisms or wastes. (Vultures, Jackals, rats and roaches)

D. Decomposer- breakdown dead organisms and return the nutrients into the soil. (Bacteria, Protist & Fungus.)

2. Food Chains pathway of energy through an ecosystem.

               Plants capture approximately 1% of the available light energy from the sun for biomass production by way of photosynthesis. Photosynthesis can be described chemically as: Light Energy + 6C02 + 6H20 = C6H1206 + 602

(1,000 Units of Energy)

Herbivores consume approximately 10% of the plant biomass produced in a typical food chain.

(100 Units of Energy)

Carnivores capture and consume about 10% of the energy stored by the herbivores.

(10 Units of Energy)

3. Food Web network of interconnected food chains

4. Ecological Pyramidsa) Pyramid of Energy

The energy available for use by organisms at each trophic level averages only about 10% of the preceding level

b) Pyramid of Biomass Biomass- the weight of an organisms after the water has been removed. Biomass decreases as you go up each trophic level

The pyramid of biomass is an energy pyramid based on the mass of dry tissue of organisms at each trophic level. Decreased radiant energy during the winter changes the number of producers and therefore the energy made available to consumers. Ecosystems in the winter have less

biomass.

2nd carnivore

1st carnivore

Herbivore

Producers

C) Pyramid of NumbersThe number of organisms decreases at each trophic level

The pyramid of numbers is an energy pyramid based on the number of organisms at each trophic level, which can be drawn by counting the number of producers (plants) in an area that support a number of herbivores, and in turn, higher-order carnivores. There are many exceptions to this pyramid because physical size of the members of a food chain can change the shape of it. For example, many aphids can be found feeding on a single plant, so the bottom layer of the pyramid would be inverted

2nd carnivore

1st carnivore

Herbivore

Producers

II. Biotic Relationships

1. Competition and Predation

A) Competition- Struggle among organisms for the limited natural resources1) Intraspecific competition - competition

by members of the same species2) Interspecific competiton- competition

with members of other species

B) Predation- organisms consuming other organisms. The predator eats the prey

2. Symbiosis a permanent, close relationship between two organisms of different species that benefits at least one of them.

A) Mutualism- symbiotic relationship in which both organisms benefit.

B) Commensalism- symbiotic relationship in which one organism benefits while the other is neither helped nor harmed.

C) Parasitism- symbiotic relationship in which one organisms benefits (parasite) and one organism is harmed (host)

3. Biological Rhythms Physiological changes in response to naturally reoccurring phenomena

A) Circadian rhythm- Daily cycle sleep/wake cycle

– Diurnal- asleep at night, awake days

– Nocturnal- awake nights, asleep days

B) Annual rhythm- biological rhythm that occurs annually– Hibernation- reduction of activity by warm blooded

animals in the winter

– Estivation- reduction of activity in summer