CHAPTER 6 ECOSYSTEM BALANCE Relationships in the Ecosystem All organisms need food to survive...
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Transcript of CHAPTER 6 ECOSYSTEM BALANCE Relationships in the Ecosystem All organisms need food to survive...
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 nitrogen-fixing 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 BiomesDivided 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
TundraVery little water
Short shallow root plants
Permafrost
Coniferous ForrestPine forest
Moderate precipitation
Higher elevations
Deciduous ForrestHardwood trees that lose their leaves
Sufficient precipitation
Rain ForrestMost precipitation
Most plant and animal species on Earth
SteppeNorthern grasslands
Cooler temperatures
PrairieCentral portions of many continents
Large areas of grasses
SavannaWarmer, southern grasslands
Located near or below the equator
DesertVery little water
Poor soil or sand
Harsh temperatures
Classified by elevation
Terrestrial Biomes Fact SheetTundra Coniferous
ForrestDeciduous Forrest
Rain Forrest
Steppe Prairie Savanna Desert