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Chapter 13 KEY CONCEPT 13.1 Ecology is the study of the relationships among organisms and their environment. Chapter 13 Ecologists study environments at different levels of organization. • Ecology is the study of the interactions among living things, and between living things and their surroundings. Chapter 13 • An organism is an individual living thing, such as an alligator. Organism Organism Chapter 13 • A population is a interbreeding group of the same species that lives in one area. Population Population Organism Organism Chapter 13 • A community is a group of populations that live together in one area. Community Community Population Population Organism Organism Chapter 13 • An ecosystem includes all of the organisms as well as the climate, soil, water, rocks and other nonliving things in a given area. Ecosystem Ecosystem Community Community Population Population Organism Organism Chapter 13 • A biome is a major regional or global community of organisms characterized by the climate conditions and plant communities that thrive there. Biome Ecosystem Ecosystem Community Community Population Population Organism Organism Chapter 13 Ecological research methods include observation, experimentation, and modeling. Chapter 13 • Experiments are performed in the lab or in the field. Chapter 13 KEY CONCEPT 13.2 Every ecosystem includes both living and nonliving factors. Chapter 13 An ecosystem includes both biotic and abiotic factors. • Biotic factors are living things. – plants – animals – fungi – bacteria plants Chapter 13 • Abiotic factors are nonliving things. – moisture – temperature – wind – sunlight – soil sunlight moisture Chapter 13 Changing one factor in an ecosystem can affect many other factors. • Biodiversity is the assortment, or variety, of living things in an ecosystem. • Rain forests have more biodiversity than other locations in the world, but are threatened by human activities. Chapter 13 • A keystone species is a species that has an unusually large effect on its ecosystem. keystone Chapter 13 • Keystone species form and maintain a complex web of life. creation of wetland ecosystem increased waterfowl Population keystone species increased fish population nesting sites for birds Chapter 13 KEY CONCEPT 13.3 Life in an ecosystem requires a source of energy. Chapter 13 Producers provide energy for other organisms in an ecosystem. • Producers get their energy from non-living resources. • Producers are also called autotrophs because they make their own food. Chapter 13 Producers provide energy for other organisms in an ecosystem. • Consumers are organisms that get their energy by eating other living or once-living resources. • Consumers are also called heterotrophs because they feed off of different things. Chapter 13 Almost all producers obtain energy from sunlight. • Photosynthesis in most producers uses sunlight as an energy source. • Chemosynthesis in prokaryote producers uses chemicals as an energy source. carbon dioxide + water + hydrogen sulfide + oxygen sugar + sulfuric acid Chapter 13 KEY CONCEPT 13.4 Food chains and food webs model the flow of energy in an ecosystem. Chapter 13 A food chain is a model that shows a sequence of feeding relationships. • A food chain links species by their feeding relationships. • A food chain follows the connection between one producer and a single chain of consumers within an ecosystem. GRAMA GRASS DESERT COTTONTAIL HARRIS’S HAWK Chapter 13 • Consumers are not all alike. – Herbivores eat only plants. – Carnivores eat only animals. – Omnivores eat both plants and animals. – Detritivores eat dead organic matter. – Decomposers are detritivores that break down organic matter into simpler compounds. carnivore decomposer Chapter 13 • Specialists are consumers that primarily eat one specific organism or a very small number of organisms. • Generalists are consumers that have a varying diet. Chapter 13 • Trophic levels are the nourishment levels in a food chain. – Primary consumers are herbivores that eat producers. – Secondary consumers are carnivores that eat herbivores. – Tertiary consumers are carnivores that eat secondary consumers. – Omnivores, such as humans that eat both plants and animals, may be listed at different trophic levels in different food chains. Chapter 13 A food web shows a complex network of feeding relationships. • An organism may have multiple feeding relationships in an ecosystem. • A food web emphasizes complicated feeding relationships and energy flow in an ecosystem. Chapter 13 KEY CONCEPT 13.5 I can describe how matter cycles in and out of an ecosystem. Chapter 13 • Matter cycles through ecosystems through • • • • Biogeochemical cycles BioGeoChemical- Chapter 13 • The 4 most common biogeochemical cycles are: – – – – Hydrologic cycle-(water cycle) Carbon cycle Nitrogen cycle Phosphorus cycle Chapter 13 • Hydrologic cycleprecipitation condensation transpiration evaporation lake groundwater surface runoff water storage in ocean Chapter 13 • Carbon Cycle carbon dioxide in air combustion respiration photosynthesis respiration decomposition of organisms fossil fuels photosynthesis carbon dioxide dissolved in water Chapter 13 • Nitrogen Cycle nitrogen in atmosphere animals plant nitrogen-fixing bacteria in decomposers roots ammonification nitrogen-fixing ammonium bacteria in soil nitrifying bacteria nitrates nitrifying bacteria nitrites denitrifying bacteria Chapter 13 • Phosphorus Cycle- rain plants geologic uplifting weathering of phosphate from rocks runoff animalsphosphate phosphate in solution in soil leaching decomposers sedimentation forms new rocks Chapter 13 KEY CONCEPT 13.6 Pyramids model the distribution of energy and matter in an ecosystem. Chapter 13 An energy pyramid shows the distribution of energy among trophic levels. • Energy pyramids compare energy used by producers and other organisms on trophic levels. • 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. energy lost energy transferred Chapter 13 Other pyramid models illustrate an ecosystem’s biomass and distribution of organisms. • Biomass is a measure of the total dry mass of organisms in a given area. tertiary consumers 75 g/m2 150g/m2 secondary consumers primary consumers producers producers 675g/m2 2000g/m2 Chapter 13 • A pyramid of numbers shows the numbers of individual organisms at each trophic level in an ecosystem. tertiary consumers 5 secondary consumers 5000 primary consumers 500,000 producers producers 5,000,000 • A vast number of producers are required to support even a few top level consumers.