Unit 2Unit 2

Ecosystems andEcosystems and

How They ChangeHow They Change

Everything in an ecosystem interacts by 2 Everything in an ecosystem interacts by 2 main processes:main processes:

and

The The SUNSUN is the is the original energy original energy source for most source for most organisms.organisms.

PRODUCECARBOHYDRATES

(SUGARS)

BREAK DOWNCARBOHYDRATES

TO RELEASEENERGY

and

SUN

AUTOTROPHS

PRODUCECARBOHYDRATES

(SUGARS) AUTOTROPHSAND

HETEROTROPHS

PhotosynthesisPhotosynthesis process that converts solar energy into process that converts solar energy into

chemical energy stored in the bonds of chemical energy stored in the bonds of organic compounds, usually carbohydratesorganic compounds, usually carbohydrates

6CO6CO22 + 6H + 6H22O + light energy O + light energy C C66HH1212OO66 + 6O + 6O22

RespirationRespiration

The release of chemical energy from food for The release of chemical energy from food for cellular usecellular use

CC66HH1212OO66 + 6O + 6O22 6CO 6CO22 + 6H + 6H22O + energyO + energy

AUTOTROPHSAUTOTROPHS Organisms that use energy to make Organisms that use energy to make

their own food their own food (producers)(producers) HETEROTROPHSHETEROTROPHS

Organisms that cannot make their own Organisms that cannot make their own food food (consumers)(consumers)

Feed on autotrophs or on other Feed on autotrophs or on other heterotrophs that feed on autotrophsheterotrophs that feed on autotrophs

All life depends on All life depends on AUTOTROPHSAUTOTROPHS..

Who Eats What in an Ecosystem Name Energy Source Examples

Producer Makes its own food grasses, ferns, trees, some bacteria

Consumer Gets energy by eating other organisms

 

Herbivore Eats only producers cows, sheep, deer, grasshoppers

Carnivore Eats only other consumers

lions, hawks, wolves, pike

Omnivore Eats both producers and consumers

bears, pigs, humans

Decomposer Breaks down dead organisms, returning nutrients to the soil or water

fungi, bacteria

Specific sequence in Specific sequence in which organisms obtain which organisms obtain energy in an ecosystemenergy in an ecosystem

•Usually only 4 or 5 levels

•Only a portion of the energy available to organisms at each level of the food chain is stored

•Only the stored energy is available to organisms at the next trophic level

The interrelated food chains in The interrelated food chains in an ecosysteman ecosystem

Trophic Trophic levellevel each step in the transfer each step in the transfer

of energy through an of energy through an ecosystemecosystem

Describes how far an Describes how far an organism is removed organism is removed from plants in a food from plants in a food chainchain

An organism cannot An organism cannot always be assigned to always be assigned to one trophic levelone trophic level

Ecosystems seldom have more Ecosystems seldom have more than 4 or 5 trophic levelsthan 4 or 5 trophic levels Not enough food or energy to feed another levelNot enough food or energy to feed another level Not all the food available at one level is actually Not all the food available at one level is actually

eaten by animals at the next leveleaten by animals at the next level Most of the energy is used in respiration, to Most of the energy is used in respiration, to

repair body tissues, and for locomotion, repair body tissues, and for locomotion, circulation, and feedingcirculation, and feeding

5-C MEASURING ENERGY FLOW: 5-C MEASURING ENERGY FLOW: PRODUCTIVITYPRODUCTIVITY

Primary productivity:Primary productivity: the rate at which the rate at which plants make more plant material by photosynthesisplants make more plant material by photosynthesis Net primary production:Net primary production: energy available energy available

to other organismsto other organisms The world’s food supplyThe world’s food supply About half is used by plants for respirationAbout half is used by plants for respiration Limits the number of organisms that can survive on earthLimits the number of organisms that can survive on earth

Numbers PyramidNumbers Pyramid compares the number of compares the number of

individuals at each trophic levelindividuals at each trophic level

Biomass PyramidBiomass Pyramid               compares the amount of biomass compares the amount of biomass

(total dry weight of the organisms in an (total dry weight of the organisms in an ecosystem)ecosystem)

Energy PyramidEnergy Pyramid               compares the total amount of compares the total amount of

energy in each trophic levelenergy in each trophic level