Post on 26-Mar-2015
Chapter 4Chapter 4
Ecosystems: Ecosystems: What What Are They and How Do Are They and How Do
They Work?They Work?
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.
BiosphereBiosphere
Ecosystems
Communities
Populations
Organisms
LEVELS
of
ORGANIZATION
FOCUSED
on
in
ECOLOGY
Species is the lowest on this hierarchy and Biosphere is the largestSpecies is the lowest on this hierarchy and Biosphere is the largest.
Vegetationand 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
Solarradiation
Energy in = Energy out
Reflected byatmosphere (34%)
UV radiation
Absorbedby ozone
Absorbedby the earth
Visiblelight
Lower stratosphere(ozone layer)
Troposphere
Heat
Greenhouseeffect
Radiated byatmosphere
as heat (66%)
Earth
Heat radiatedby the earth
Solar Capital
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.
• 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
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.
Po
pu
lati
on
Siz
e
Low High Temperature
Zone ofintolerance
Zone ofphysiological stress
Optimum range Zone ofphysiological stress
Zone ofintolerance
Noorganisms
Feworganisms
Lower limitof tolerance
Abundance of organismsFew
organismsNo
organisms
Upper limitof tolerance
Range of tolerance for a population of organisms, such as fish,to an abiotic environmental factor—in this case, temperature.
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.
ECOLOGY
Food Chain – A chain illustrating the organisms and their food source.
Grass grasshopper bird
ECOLOGY
Ecological Pyramid
A food chain
that shows the relationship between the organisms in each trophic
level.
The figures represent number of individuals counted at each trophic
level.
Ecological Pyramid of Numbers
• 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
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%.)
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
Precipitation
Precipitationto ocean Evaporation
EvaporationFromocean
Surface runoff(rapid)
Ocean storage
Condensation
Transpiration
Rain clouds
Infiltration andpercolation
Transpirationfrom plants
Groundwater movement (slow)
Groundwater movement (slow)
RunoffRunoff
Surface runoff (rapid)Surface runoff (rapid)
Precipitation
Water (Hydrologic) Cycle
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)
Phosphorus Cycle
Phosphate Mining
Fertilizer containing phosphates
Animal waste
Phosphate Rock
Dissolved PhosphatesAnimal Excretion
Erosion
Uplifting into rocks