Transcript chapter 6 - Nutley Public Schools

CHAPTER 6
ECOSYSTEM
BALANCE
Relationships in the Ecosystem
• All organisms need food to survive
• Consumers that must actively hunt for other
organisms as a source of food are predators
• The organisms hunted for food are called prey
Ex: the lynx and the snowshoe hare
Symbiosis
• Symbiosis - two species
live closely together in an
ecosystem. From ancient
Greek – syn (with) biosis
(living)
• Can take place between
plant, animal, fungi, or
any combination
Ex: crocodile and croc-bird,
sucker fish and the shark,
us and the Earth
Ecosystem Relationships
• Parasitisim – one
organism feeds on the
tissues or body fluids of
another, called the host.
Parasites may or may not
cause harm to their hosts
•
•
Ex: West Nile Disease is a virus
that is passed from infected bird
to other birds, mammals and even
humans by the bite of a mosquito.
The mosquito is also known as a
vector because it needs blood
meals to survive and reproduce
Parasitism
One organism (parasite)
feeds directly from
another organism (host).
The parasite benefits and the
host is harmed
(sometimes lethally).
Ex: tapeworm, hookworm,
tick, bed bug
Commensalism
• A relationship that
benefits one organism and
neither helps nor hurts the
other (neutral).
• Comes from the Latin
com mensa “to share a
table”
Ex: cattle egret feeds on
insects stirred up as cattle
or horses graze the grass
for food.
Mutualism
• A relationship where both
organisms help each
other. Both organisms
benefit in a “win-win
relationship”.
Ex: legumes and nitrogenfixing bacteria;
pollinating plants by bees
and butterflies, clownfish
and the sea anenome
Ecological Succession
• The Earth is made of
rock
• Lichens (fungus and
algae) can live on
bare rock
• Lichens secrete acid
which breaks down
the rock into soil
• Lichens are known as
a pioneer community
Ecological Succession
• Lichens are replaced by
grasses
• Grasses further enrich the
soil allowing shrubs to grow
• Pine trees replace shrubs
• Deciduous trees
(oaks, maples, elms)
replace pines
• Climax community – a
community that does not
experience additional
succession
•
Secondary Succession
• Secondary succession
— occurs when a
community has been
cleared by a major
disturbance (fires,
storms, human
activity) that doesn’t
destroy the soil
Other Forms of Succession
Aquatic Succession
 Aquatic habitats also experience
succession
 Water gradually gain nutrients and
supports reeds and other water
plants
 Organic matter (sediment) collects
on the lake floor
 More and more water plants cover
the surface of the lake
 When the lake fills in with
sediment is becomes a marsh
 Land plants gradually replace the
marsh plants to change the
community into a fertile meadow
Island Succession
 Island succession occurs much
like it does on land
 Islands appear quickly after
volcanic eruptions
 Any organisms found on an island
usually arrive by water, wind or
other organisms
 Most islands have large bird
populations
 Organisms can adapt to fill many
niches because there is no
competition for resources
(Galapagos finches)
Balance in the Ecosystem
• All elements in an ecosystem are
connected to each other (abiotic and biotic
factors)
• All processes in the ecosystem link
together in a complex arrangement (food
web)
• All natural ecosystems are STABLE –
maintain a state of balance or equlibrium
• Systems that do not maintain equilibrium
do not survive
Ecosystem Balance
• Major disruptions cause major changes in
an ecosystem
• A new ecosystem will develop to replace
the old one that was destroyed.
• Evolution of organisms is part of this
development
• Organisms MUST adapt to majors changes
or die out (face extinction)
Ecosystem Balance
• Chaos Theory – mathematical explanation
of the effect small and large changes have
on a particular ecosystem.
• Analyzing a complex system with both
abiotic and biotic factors and multiple
organisms can very very difficult.
• Hard to predict what the effect even one
small change will have in the furture of an
ecosystem.
BIOMES
• Biome – A major type of ecosystem with
distinctive temperature range, rainfall and
organisms
• Two kinds of biomes: terrestrial (land) and
aquatic (water)
• Terrestrial biomes are classified by average
temperatures and precipitation
• Aquatic biomes are classified by water depth,
nutrient levels and location relative to land
Terrestrial Biomes
Divided into 8
major biomes
• Desert and
Tundra – very
little water, small
amount of
biomass
Terrestrial Biomes
• Forest – 75% of the
Earth’s biomass
3 forest biomes:
Coniferous (pine)
Deciduous (trees
that lose leaves)
Rain (most water,
6% of all biomass)
Terrestrial Biomes
Grasslands –
22% of Earth’s land
surface
8% of Earth’s
biomass
Steppe – northern
Prairie - central
Savanna - southern
TERRESTRIAL BIOMES
Tundra
Very little water
Short shallow
root plants
Permafrost
Coniferous Deciduous Rain
Forrest
Forrest
Forrest
Pine forest
Moderate
precipitation
Higher elevations
Hardwood trees
that lose their
leaves
Sufficient
precipitation
Most
precipitation
Most plant and
animal species on
Earth
Steppe
Prairie
Savanna
Desert
Northern
grasslands
Cooler
temperatures
Central portions
of many
continents
Large areas of
grasses
Warmer, southern
grasslands
Located near or
below the equator
Very little water
Poor soil or sand
Harsh
temperatures
Classified by
elevation
Terrestrial Biomes Fact Sheet
Tundra
Coniferous Deciduous Rain
Forrest
Forrest
Forrest
Steppe
Prairie
Savanna
Desert