Ecosystems: What Are They and How Do They Work?

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Chapter 4

• Ecosystems What Are They and How Do They Work?

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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.

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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
Biosphere
Biosphere
Ecosystems
Communities
Populations
Organisms
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Population
Species
Community
Biome
Biosphere
Ecosystem
Species is the lowest on this hierarchy and
Biosphere is the largest.
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homeostasis
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Oceanic crust
Continental crust
Biosphere
Vegetation and animals
Lithosphere
Upper mantle
Soil
Crust
Asthenosphere
Rock
Lower mantle
core
Mantle
Crust (soil and rock)
Biosphere (Living and dead organisms)
Atmosphere (troposphere,
stratosphere) (air)
Lithosphere (crust, top of upper mantle)
Hydrosphere (water)
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Solar Capital
Solar radiation
Energy in Energy out
Reflected by atmosphere (34)
Radiated by atmosphere as heat (66)
UV radiation
Lower stratosphere (ozone layer)
Visible light
Greenhouse effect
Troposphere
Absorbed by ozone
Heat
Absorbed by the earth
Heat radiated by the earth
Earth
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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.

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Biotic Factors in an Aquatic Ecosystem
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Abiotic Factors in Terrestrial and Aquatic
Ecosystems
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
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Ecotones Ecosystem Boundaries
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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.

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Range of tolerance for a population of organisms,
such as fish, to an abiotic environmental
factorin this case, temperature.
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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.

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ECOLOGY
Food Chain A chain illustrating the organisms
and their food source. Grass
grasshopper bird
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A food chain illustrates the transfer of energy
from one trophic level to the next.
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ECOLOGY
Food Web multiple chains assembled into one
large web.
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ECOLOGY
Ecological Pyramid A food chain that shows the
relationship between the organisms in each
trophic level.
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Ecological Pyramid of Numbers
The figures represent number of individuals
counted at each trophic level.
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Ecological Pyramid of Biomass

• The total dry weight of organisms in a particular
  trophic level is referenced as biomass.

BIOMASS of organisms x the weight of an
average individual
biomass
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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.)

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Ecological Pyramid of Energy
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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

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

• 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)

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