Transcript ch 13 principle of ecology 1011

Ecology
Chapter 13: Principles of
Ecology
• Ecology is the study of the interactions among living
things, and between living things and their surroundings.
• Ecologists group living things into an organizational
system.
• An organism is an
individual living thing.
• A population is a group of the same
species that lives in one area.
• A community is a group of different
species that live together in one area.
• An ecosystem includes all of the organisms as well as the
climate, soil, water, rocks and other nonliving things in a
given area.
• A biome is a major regional or global community of
organisms characterized by the climate conditions and plant
communities that thrive there.
An ecosystem includes both biotic and abiotic factors.
• Biotic factors are living things.
– plants
– animals
– fungi
– Bacteria
Mangrove trees
Bracket fungi on mangrove tree
Mangrove crabs
•
–
–
–
–
–
Abiotic factors are nonliving things.
moisture
temperature
wind
sunlight
Soil
The balance of these
determines which
living things can
survive in a given
environment.
• Biodiversity is the assortment, or variety, of living things in
an ecosystem.
• Rain forests have more biodiversity than other locations in
the world (50% of all species)
Life in an ecosystem requires energy. Producers provide
energy for other organisms in an ecosystem.
• Producers get their energy from non-living resources (the
sun, carbon dioxide & water) meaning they make their own
food through photosynthesis. They are also called
autotrophs.
• All ecosystems depend on producers, because they provide
the basis for the ecosystems energy.
• Consumers are organisms that get their energy by eating
other living or once-living resources.
• Consumers are also called heterotrophs because they feed off of
different things.
• Consumers are not all alike:
–
–
–
–
Herbivores eat only plants. Cows, Horses.
Carnivores eat only animals. Tigers, Sharks.
Omnivores eat both plants and animals. Humans, Rats.
Detritivores (aka scavengers) eat dead organic matter. Millipede,
Hyena.
– Decomposers are detritivores that break down organic matter into
simpler compounds. Fungus, Bacteria.
carnivore
decomposer
detritivore
Almost all producers obtain energy from sunlight.
• Photosynthesis in most producers uses sunlight as an
energy source.
• Chemosynthesis in prokaryote producers uses chemicals
as an energy source.
A food chain is a model that shows a sequence of feeding
relationships & shows the flow of energy in an ecosystem.
• A food chain links species by their feeding relationships.
• A food chain follows the connection between one producer
and a single chain of consumers within an ecosystem.
GRAMA GRASS
Producer
DESERT COTTONTAIL
Consumer
HARRIS’S HAWK
Consumer
• Arrows in the
chain always
show the direction
of energy flow.
• Each organism may have multiple feeding relationships in
an ecosystem, which is shown by a Food Web
Important Members of Food Webs:
• A keystone species is a species that has an unusually large
effect on its ecosystem.
• Keystone species form and maintain a complex web of life.
creation of
wetland
ecosystem
increased waterfowl
Population
keystone species
increased
fish
population
nesting
sites for
birds
• The beaver is a keystone species, because it creates
wetlands by creating dams. It causes:
• Greater number & wider variety of fish
• More fish eating birds: herons & kingfishers
• More insects and insect-eating birds on the shore
• Waterfowl nest on the shore
• Without the beaver, there would be a decrease in all
these organisms.
• Specialists are consumers
that primarily eat one
specific organism or a very
small number of
organisms. They are very
sensitive to changes in the
availability of prey.
• Koalas are specialists
because they eat only
eucalyptus leaves.
• Generalists are consumers that have a varying diet. A gray
wolf feeds on elk, moose, deer, beavers & even mice.
• Trophic levels are the nourishment levels in a food chain.
– Primary consumers are herbivores that eat producers. (2nd Trophic
Level)
– Secondary consumers are carnivores that eat herbivores. (3rd
Trophic Level)
– Tertiary consumers are carnivores that eat secondary consumers.
(4th Trophic Level)
– Omnivores, such as humans that eat both plants and animals, may
be listed at different trophic levels in different food chains. (2nd, 3rd,
or 4th Trophic Level)
3rd Trophic Level
2nd Trophic Level
Primary Consumer
Secondary Consumer
4th Trophic Level
Tertiary Consumer
Energy Pyramids
• Energy pyramids
compare energy used
by producers and other
organisms on trophic
levels.
• Between each tier
of an energy
pyramid, up to 90
percent of the
energy is lost into
the atmosphere as
heat.
• Only 10 percent of
the energy at each
tier is transferred
from one trophic
level to the next.
• A pyramid of numbers shows the numbers of individual
organisms at each trophic level in an ecosystem.
tertiary
consumers
5
secondary
consumers
5000
primary
consumers
500,000
producers
producers
5,000,000
• A vast number of producers are required to support even a
few top level consumers.
Water cycles through the environment.
• The hydrologic, or water, cycle is the circular pathway of
water on Earth.
• Organisms all have bodies made mostly of water.
precipitation
condensation
transpiration
evaporation
lake
groundwater
surface
runoff
water storage
in ocean
• Carbon is the building block of life.
– The carbon cycle moves carbon from the atmosphere,
through the food web, and returns to the atmosphere.
– Carbon is emitted by the burning of fossil fuels.
– Some carbon is stored for long periods of time in areas
called carbon sinks.
carbon
dioxide
in air combustion
respiration
photosynthesis
respiration
decomposition
of organisms
fossil fuels
photosynthesis
carbon dioxide
dissolved in water
• The nitrogen cycle mostly takes place underground.
– Some bacteria convert gaseous nitrogen into ammonia
through a process called nitrogen fixation.
– Some nitrogen-fixing bacteria live in
nodules on the
nitrogen in
atmosphere
roots of plants;
animals
others live
freely in
the soil.
plant
nitrogen-fixing
bacteria in
decomposers
roots
ammonification
nitrogen-fixing
ammonium
bacteria in soil
nitrifying
bacteria
nitrates
nitrifying
bacteria
nitrites
denitrifying
bacteria
– Ammonia released into the soil is transformed into
ammonium.
– Nitrifying bacteria change the ammonium into nitrate.
– Nitrogen moves through the food
web and returns nitrogen in
atmosphere
to the soil during
animals
decomposition.
plant
nitrogen-fixing
bacteria in
decomposers
roots
ammonification
nitrogen-fixing
ammonium
bacteria in soil
nitrifying
bacteria
nitrates
nitrifying
bacteria
nitrites
denitrifying
bacteria
• The phosphorus cycle takes place at and below ground
level.
– Phosphate is released by the weathering of rocks.
– Phosphorus moves through the food web and returns to
the soil during
decomposition.
rain
geologic uplifting
– Phosphorus leaches
into groundwater
weathering of
phosphate from rocks
from the soil and
runoff
plants
is locked in
sediments.
animalsphosphate
phosphate in solution
in soil
– Both mining and
leaching
agriculture add
sedimentation
phosphorus into
decomposers
forms new rocks
the environment.