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Chapter 4 Ecosystems: What Are They and How Do They Work?

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Presentation on theme: "Chapter 4 Ecosystems: What Are They and How Do They Work?"— Presentation transcript:

1 Chapter 4 Ecosystems: What Are They and How Do They Work?

2 ECOLOGY Ecology is the study of the connection between organisms and their living and non-living environments. The average number of organisms that can be sustained in an ecosystem is known as carrying capacity. Food, water, and shelter are known as limiting factors.

3 Biosphere Ecosystems Communities Populations Organisms L E V E L S of O R G A N I Z A T I O N F O C U S E D on in E C O L O G Y

4 Species is the lowest on this hierarchy and Biosphere is the largest Species is the lowest on this hierarchy and Biosphere is the largest.



7 Vegetation and animals Soil Rock Biosphere Crust core Mantle Lithosphere (crust, top of upper mantle) Hydrosphere (water) Atmosphere (troposphere, stratosphere) (air) Biosphere (Living and dead organisms) Crust (soil and rock) Oceanic crust Continental crust Lithosphere Upper mantle Asthenosphere Lower mantle

8 Solar radiation Energy in = Energy out Reflected by atmosphere (34%) UV radiation Absorbed by ozone Absorbed by the earth Visible light Lower stratosphere (ozone layer) Troposphere Heat Greenhouse effect Radiated by atmosphere as heat (66%) Earth Heat radiated by the earth Solar Capital

9 ECOLOGY Abiotic – All of the non-living elements in an ecosystem like air, water, and temperature. Biotic – All of the living elements in an ecosystem.

10 Biotic Factors in an Aquatic Ecosystem

11 Sunlight Temperature Precipitation Wind Latitude (distance from equator) Altitude (distance above sea level) Fire frequency Soil Light penetration Water currents Dissolved nutrient concentrations (especially N and P) Suspended solids Salinity Abiotic Factors in Terrestrial and Aquatic Ecosystems

12 Ecotones: Ecosystem Boundaries

13 Tolerance Range of Tolerance: range of chemical and physical conditions that must be maintained for populations of a particular species to stay alive and grow, develop, and function normally. Law of Tolerance: the existence, abundance, and distribution of a species in an ecosystem are determined by whether the levels of one or more physical or chemical factors fall within the range tolerated by the species.

14 Population Size LowHighTemperature Zone of intolerance Zone of physiological stress Optimum range Zone of physiological stress Zone of intolerance No organisms Few organisms Lower limit of tolerance Abundance of organisms Few organisms No organisms Upper limit of tolerance Range of tolerance for a population of organisms, such as fish, to an abiotic environmental factorin this case, temperature.

15 Ecology Biodiversity is the number and variety of organisms found within a certain region. Extinction is when a species is no longer in existence. Endangered means a species is in danger of extinction throughout all of a significant portion of its range.

16 ECOLOGY Food Chain – A chain illustrating the organisms and their food source. Grass grasshopper bird

17 A food chain illustrates the transfer of energy from one trophic level to the next.


19 ECOLOGY Food Web – multiple chains assembled into one large web.

20 ECOLOGY Ecological Pyramid A food chain that shows the relationship between the organisms in each trophic level.

21 The figures represent number of individuals counted at each trophic level. Ecological Pyramid of Numbers

22 The total dry weight of organisms in a particular trophic level is referenced as biomass. Ecological Pyramid of Biomass BIOMASS = # of organisms x the weight of an average individual

23 Ecological Pyramid of Energy Energy in ecosystems flows from producers to consumers. Energy is depicted in kilocalories. Ecological efficiency: % of usable energy transferred from one trophic level to the next. (Average is about 10%.)

24 Ecological Pyramid of Energy


26 Nutrient Cycles Cycling of materials between the environment and organisms. Chemical and biological processes. Examples: –Water cycle –Carbon cycle –Nitrogen cycle –Phosphorus cycle –Sulfur cycle –Oxygen cycle

27 Precipitation to ocean Evaporation From ocean Surface runoff (rapid) Ocean storage Condensation Transpiration Rain clouds Infiltration and percolation Transpiration from plants Groundwater movement (slow) Runoff Surface runoff (rapid) Precipitation Water (Hydrologic) Cycle

28 Carbon Cycle

29 Nitrogen Cycle

30 Nitrogen Fixation: bacteria convert nitrogen to ammonia Nitrification: bacteria convert ammonia to nitrite and nitrate, which are used by plants Assimilation: plant roots absorb ammonia and nitrate Ammonification: decomposers convert dead organisms and waste to simpler compounds Denitrification: bacteria convert ammonia back into nitrite and nitrate, which are released into the air (cycle begins again)

31 Phosphorus Cycle Phosphate Mining Fertilizer containing phosphates Animal waste Phosphate Rock Dissolved Phosphates Animal Excretion Erosion Uplifting into rocks

32 The Sulfur Cycle

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