Chapter 3.1 – Communities

  • Limiting Factors = Factors that affect an organism’s ability to survive in its environment, such as the availability of water and food, predators, and temperature
  • Tolerance = The ability of an organism to withstand fluctuations in biotic and abiotic environmental factors

  • Succession = orderly, natural changes and species replacements that take place in the communities of an ecosystem.
  • Succession occurs in stages. At each stage, different species of plants and animals may be present.
  • 2 types of succession—primary and secondary.
  • Primary Succession = The colonization of barren land by communities of organisms.
  • Takes place on land where there are no living organisms.
  • The first species to take hold in an area like this are called pioneer species.
  • After some time, primary succession slows down and the community becomes fairly stable, or reaches equilibrium.
  • A stable, mature community that undergoes little or no change in species is a climax community.
  • Secondary succession = the sequence of changes that takes place after an existing community is severely disrupted in some way.
  • Secondary succession, however, occurs in areas that previously contained life, and on land that still contains soil.
  • Because soil already exists, secondary succession may take less time than primary succession to reach a climax community.

3.2 BIOMES

1. What is a biome? Large group of ___ecosystems____ that share the same ___climax___

_____community______.

2. Aquatic Biomes. ~75% of the Earth’s surface = _water__.

Types: ___Freshwater____, ____Saltwater_____, _____wetlands_____

3. Marine Biomes. Ecologists study different zones…

Shallow, sunlit zone = __photic __ zone

Deeper, unlighted zone = _aphotic___ zone

4. Estuaries = Where __river__ meets __ocean__...freshwater mixes with saltwater.

5. Intertidal zone. The gravitational pull of the _sun_ & _moon_ causes the rise & fall of ocean tides. It’s the portion of the shoreline bw the high & low lines.

6. Plankton = __small__ organisms that drift & float in the _photic_ zone.

Includes autotrophs, eggs, juvenile stages of marine animals.

They form the __base_ of aquatic food chains!

7. Terrestrial Biomes: _Tundra__, __Taiga___, ___Desert__, ___Grasslands__, __Temperate Deciduous Forest______, ___Rain Forest______

8. Tundra.

Rarely rises above ___freezing____.

Top layer of soil thaws during summer. Supports _shallow__-_rooted_ plants. Soil _lacks__ _in_ __nutrients_____.

__Permafrost______= frozen layer of soil. Treeless.

9. Taiga.

Aka Boreal or Northern Coniferous Forest.

__Coniferous____ trees (cones, like spruce, fir)

Soil is waterlogged, __lacks______nutrients____.

Slightly warmer & wetter than tundra.

Supports lynx, hare, caribou, elk, moose.

10. Desert.

_Arid_, sparse plant life.

_<25__ cm of precipitation annually (major limiting factor!)

Adaptations to conserve water…waxy.

11. Grassland.

_25-75__ cm of precipitation annually.

__Rich__ __soil__, grasses.

Dry season. Breadbasket of the world…grains!

__Grazing___ & __Prairie__ animals (bison, deer, elk, jack rabbits, prairie dogs)

Similar = African Savanna

12. Temperate Deciduous Forest.

__70-150__ cm of precipitation annually.

__Broad_ - __leaved__ hardwood trees (maple, oak).

Soil = _rich__ top layer, clay deeper layer

Squirrels, mice, rabbits, deer, bear, birds.

13. Rain Forest.

Greatest __biodiversity____!

Tropical rain forests = warm, wet, lush plant growth. _200-600__ cm of precipitation annually.