13.1 Ecologists Study Relationships

Introduction To Ecology Ecology – the study of living things and their relationship with each other and with the environment *Ecology can be studied at different levels, from a local to a global scale

Levels of Organization 1. Organism – an individual living thing, such as an alligator 2. Population – group of same species that lives in one area, such as a group of alligators living in a swamp

Levels of Organization 3. Community – all of the living things in a given area. Ex: alligators, fish, plants, birds. 4. Ecosystem – all of the living and nonliving things in a given area. Ex: All of the above and soil, rocks, water, etc.

Levels of Organization 5. Biome – a major regional or global community of organisms, usually characterized by the climate conditions and plant communities that thrive there. Examples: tropical, grassland, desert, temperate, taiga, tundra

Levels of Organization 6. Biosphere – portion of the Earth where all life exists

Ecological research methods include… Observation – the act of carefully watching something over time. Direct: naked eye, binoculars Indirect: feces, recent kill Experimentation – scientists can perform experiments in the lab or the field. Modeling – Using computer or mathematical models to describe and model nature

13.2 Biotic and Abiotic Factors Every ecosystem includes both living and nonliving factors

Biotic factors are living things, or things that were once living Examples: plants, animals, fungi, bacteria Each organism plays a particular role in the ecosystem.

Abiotic Factors are nonliving Examples: moisture, temperature, wind, sunlight, soil. The balance of these factors determines which living things can live in a particular environment.

Biodiversity is important to an ecosystem Biodiversity is the assortment, or variety, of living things in an ecosystem. Keystone species: A species that has an unusually large effect on its ecosystem. The loss of a keystone species from an ecosystem can have a ripple effect. Example: Beavers create dams which are an ecosystem used by a wide variety of species. http://www.youtube.com/watch?v=kEh4r4iQiBU

13.3 Energy in Ecosystems Life in an ecosystem requires a source of energy Producers provide energy for other organisms in an ecosystem. Producer: An organism that get their energy from non-living resources. Example: Plants Also called autotrophs Get energy from photosynthesis or chemosynthesis Chemosynthesis: process by which an organism forms carbohydrates using chemicals as an energy source.

Energy In Ecosystems Consumers are organisms that get their energy by eating other living things Also called heterotrophs All consumers somehow depend on producers for food. Examples: wolf, human, rabbit

13.4: Food chains and food webs Food chains and food webs model the flow of energy in an ecosystem.

Food Chains & Food Webs Food chain: a model that shows a sequence of feeding relationships. Shows the transfer of energy from one organism to another Each level of nourishment in a food chain is called a trophic level (label trophic levels)

Not all consumers are alike. Herbivores: Eat only plants. Example: rabbits Carnivores: Eat only animals. Example: lion Omnivore: Eat both plants and animals. Example: kangaroo rat. Detritivores: Eat detritus, or dead organic matter. Examples: millipede Decomposer: A type of detritivore that breaks down organic matter into simpler compounds, returning vital nutrients back into their environment. Example: fungi

Other types of consumers… Specialists: a consumer that primarily eats one specific organisms or feeds on a very small number of organisms. Very sensitive to changes in the availability of prey. Generalists: consumers that have a varying diet (most species).

Energy flows from the lowest trophic level to the highest trophic level Producer to primary consumer to secondary consumer to tertiary consumer Primary consumers are herbivores (or omnivores) Secondary consumers are carnivores (or omnivores) Tertiary consumers are carnivores (or omnivores)

A food web is a model that shows the complex network of feeding relationships and the flow of energy within an ecosystem.

Energy Pyramids A pyramid of numbers shows the numbers of individual organisms at each trophic level in an ecosystem. Between each tier of an energy pyramid, up to 90 percent of the energy is lost into the atmosphere as heat. Only 10 percent of the energy at each tier is transferred from one trophic level to the next. A vast number of producers are required to support even a few top level consumers. tertiary consumers secondary primary producers 5 5000 500,000 5,000,000

13.5 KEY CONCEPT Matter cycles in and out of an ecosystem. It changes form, but does not disappear. The total amount of matter remains the same. http://www.youtube.com/watch?v=09_ sWPxQymA

Water cycles through the environment. The hydrologic, or water, cycle is the circular pathway of water on Earth. It is driven by the sun. Water changes from vapor to liquid to ice and back again. Organisms all have bodies made mostly of water. precipitation condensation transpiration evaporation water storage in ocean surface runoff lake groundwater seepage

Elements essential for life also cycle through ecosystems Elements essential for life also cycle through ecosystems -examples: oxygen, carbon A biogeochemical cycle is the movement of a particular chemical through the biological and geological parts of an ecosystem.

The Oxygen Cycle Oxygen can cycle indirectly through an ecosystem by the cycling of other nutrients. oxygen respiration carbon dioxide photosynthesis

The Carbon Cycle Carbon is the building block of living organisms. Carbon comes in all three forms (solid, liquid, gas) CO2 gas HCO3 (bicarbonate- dissolved in water) Fossil Fuels (underground) oil, natural gas, coal Carbonate rocks (limestone) Dead Organic Matter http://ed.ted.com/lessons/the-carbon-cycle-nathaniel-manning fossil fuels photosynthesis carbon dioxide dissolved in water decomposition of organisms respiration carbon dioxide in air combustion

The nitrogen cycle mostly takes place underground. Some bacteria convert gaseous nitrogen into ammonia through a process called nitrogen fixation. Some nitrogen-fixing bacteria live in nodules on the roots of plants; others live freely in the soil. Lightning can split nitrogen molecules in the atmosphere which can add nitrogen to the soil. nitrogen in atmosphere animals denitrifying bacteria nitrifying ammonium ammonification decomposers plant nitrogen-fixing bacteria in soil bacteria in roots nitrates nitrites

Nitrogen Cycle Continued Ammonia (NH3) released into the soil is transformed into ammonium – some is taken up by plants Nitrifying bacteria change the ammonium into nitrate (nitrification) Nitrate is taken up by plants and converted into organic compounds like amino acids and proteins (assimilation). Nitrogen moves through the food web and returns to the soil during decomposition as ammonium (ammonification)

Phosphorus Cycle The phosphorus cycle takes place at and below ground level – it does not include an atmospheric portion. 1. Phosphate is released by the weathering of rocks. 2. Plants and fungi found near plant roots are able to take up phosphate 3. Phosphorus moves through the food web and returns to the soil during decomposition. geologic uplifting rain weathering of phosphate from rocks runoff sedimentation forms new rocks leaching phosphate in solution animals plants decomposers phosphate in soil Phosphorus leaches into groundwater from the soil and is locked in sediments. Both mining and agriculture add phosphorus into the environment.