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CHAPTER 6

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.

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CHAPTER 6

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  1. CHAPTER 6 ECOSYSTEM BALANCE

  2. 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

  3. 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

  4. 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

  5. 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

  6. 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.

  7. 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

  8. 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

  9. 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

  10. 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

  11. 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) Other Forms of Succession

  12. 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

  13. 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)

  14. 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.

  15. 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

  16. Terrestrial Biomes Divided into 8 major biomes • Desert and Tundra – very little water, small amount of biomass

  17. 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)

  18. Terrestrial Biomes Grasslands – 22% of Earth’s land surface 8% of Earth’s biomass Steppe – northern Prairie - central Savanna - southern

  19. TERRESTRIAL BIOMES

  20. Terrestrial Biomes Fact Sheet

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