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.Ecosystem 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 PopulationsCommunities 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 CycleThe 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 (NO 3 -), nitrites (NO 2 -), ammonia (NH 3 ). 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 Levels A) Producers- autotrophic plants B) Consumers- heterotrophic animals 1) 1 ST order consumers are herbivores- they eat only plants. 2) 2 nd order consumers are carnivores- they eat other animals 3) 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 = C6H (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 Pyramids a) 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. 2 nd carnivore 1 st carnivore Herbivore Producers

C)Pyramid of Numbers The 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 2 nd carnivore 1 st carnivore Herbivore Producers

II. Biotic Relationships

1. Competition and Predation A) Competition- Struggle among organisms for the limited natural resources 1) Intraspecific competition - competition by members of the same species 2) 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