Energy in Ecosystems Where does the energy 18.3 in an...
Transcript of Energy in Ecosystems Where does the energy 18.3 in an...
8/21/2015
1
Energy in Ecosystems
18.3
Where does the energy in an ecosystem come
from?
Producers provide the energy for organisms in an
ecosystem.
• Producers or autotrophsmake their own food…
• …so, where do producers get their energy from??
The Sun
Producers make their own food by:
• Photosynthesis: process where light is converted to energy in the form of glucose
–Photoautotrophs
• Chemosynthesis: the use of chemicals to make food
–Chemoautotrophs
Energy flows through Ecosystems from producers
to consumers• Consumers get their energy from
eating living or once-living resources
• Consumers are also called heterotrophs because they feed on many different things
8/21/2015
2
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
Food Chains & Food Webs
Food chains and food webs are two types of feeding
relationships and model the flow of
energy in an ecosystem.
A food chain is a model that shows a sequence of feeding relationships.
• Simple path through an ecosystem
• A food chain follows the connection between one producer and a single chain of consumers within an ecosystem.
A food web contains several food chains.
• An organism may have several feeding relationships in an ecosystem.
• A food web emphasizes complicated feeding relationships and energy flow in an ecosystem.
• More realistic model
12
How Many Chains are in
this web?
8/21/2015
3
• Specialists are consumers that primarily eat one specific organism or a very small number of organisms.
• Generalists are consumers that have a varying diet.
Trophic levels are the nourishment levels in a food chain.
1st Level - Producers
2nd Level - Primary consumers are herbivores that eat producers.
3rd Level - Secondary consumers are carnivores that eat herbivores.
4th Level - Tertiary consumers are carnivores that eat secondary consumers.
Primary Consumer
Secondary Consumer
TertiaryConsumer
–Omnivores, such as humans that eat both plants and animals, may be listed at different trophic levels in different food chains.
16
Food Chain
Producer (trapped
sunlight & stored food)
1st order Consumer
2nd Order Consumer
3rd Order consumer
4th Order Consumer
17
Food Web
18
Food Chains Show Available Energy
8/21/2015
4
10% Rule• Energy flows up the food chain from
the lowest trophic level to the highest.• Only 10% of the energy is transported
from 1 trophic level to the next.• Ex. producer � primary consumer• 10% of the energy is transferred to
the consumer while the other 90%is either used by the organism or lost as heat to the atmosphere
Pyramid Models
Pyramids model the distribution of energy and matter in an ecosystem.
• 3 Types of pyramids:
-energy pyramid
-biomass pyramid
-pyramid of numbers
Energy Pyramid• Shows how
available energy is distributed among trophic levels in an ecosystem
• Outward arrows indicate energy lost as heat and waste
• 10% transfers to next level
energy transferredenergy
lost
24
Energy Pyramid
8/21/2015
5
25
Biomass Pyramid• Compares the biomass of different trophic
levels within an ecosystem
• Biomass: measure of the total dry mass of organisms in a given area
tertiary
consumers
secondary
consumers
primary
consumers
producers
75 g/m2
150g/m2
675g/m2
2000g/m2producers 2000g/m2
Pyramid of Numbers
• Shows the number of individual organisms at each trophic level in an ecosystem
tertiary
consumers
secondary
consumers
primary
consumers
producers
5
5000
500,000
5,000,0005,000,000producers
28
Changing one factor in an ecosystem can affect many other factors.
• Biodiversity: variety of life
-the more biodiversity in an ecosystem, the more complex it is
• Keystone species: a species that has an unusually large effect on an ecosystem
29
• Beavers are a keystone species because they create an ecosystem used by a wide variety of species
creation ofwetland
ecosystem
increased waterfowl
Population
increased fish
populationnesting sites for
birds
keystone species