lecture 15: biomes

hierarchy of ecology

levels of organization:

1. biosphere

2. biome

3. ecosystem

4. community

5. population

6. organism

ecosystem

combo of biotic & abiotic factors w in a given area

biome

a set of similar ecosystems characterized by similar biotic communities, abiotic factors, & climatic conditions around the globe

latitude

distance from the equator (both N & S)

• higher latitude = farther away from the equator

altitude

the height of an area from sea or ground level

terrestrial biomes

influenced by 2 main factors

• dryness: how much available H2O

• temp: how hot or cold it is

  • higher latitude/altitude = lower temp

  • lower latitude/altitude = higher temp

key drivers of biomes

• latitude

• altitude

terrestrial biomes

1. tundra

2. boreal forest (tiaga)

3. temperate deciduous forest

4. grasslands

5. chaparral

6. desert

7. tropical rainforest

tundra

• cold, dry, short growing season

• no trees

• permafrost (frozen soil → releases greenhouse gases when melted)

• plants: grasses, shrubs

• animals: polar bears, foxes, birds, mosquitoes

boreal forest (tiaga)

• cold but warmer than tundra

• more precipitation

• evergreen trees (gymnosperms)

• LOW plant diversity

• largest terrestrial biome

• animals: bears, wolves, birds

temperate deciduous forest

• climate:

  • moderate temp

  • distinct seasons (fall, winter, spring, summer)

  • moderate precipitation

• vegetation

  • deciduous trees (lose leaves in fall)

    • oak, maple

  • adaptation: leaf drop → conserve H2O in winter

• soil:

  • fertile → supports biodiversity

• animals: deer, foxes, squirrels, birds

grasslands (savannas/prairies)

• climate:

  • moderate rainfall (NOT enough for trees)

  • seasonal droughts

  • frequent fires

• vegetation

  • dominated by grasses

  • A few trees

• adaptations

  • fire-resistant plants

  • deep roots

• animals: grazers (bison, zebras), predators (lions, wolves)

chapparal

• climate:

  • mild, wet winters

  • hot, drying summers

• vegetation: shrubs & small trees

• key feature: frequent fires

• adaptations:

  • fire resistant plants

  • seeds that germinate

• animals: deer, coyotes, small mammals

desert

• climate: VERY low precipitation & can be hot OR cold

• vegetation: sparse, cacti, succulents

• adaptations: H2O storage & reduced leaves (spines)

• animals: nocturnal (avoid heat), reptiles, rodents

tropical rainforest

• climate: warm yr round, v high precipitation

• vegetation: dense forests & multiple layers (canopy, understory)

• biodiversity: HIGHEST on earth

• soil: nutrient poor (nutrients stored in plants)

• animals: extremely diverse (insects, birds, mammals)

lakes & ponds

key zones:

1. littoral zone

2. limnetic zone

3. profundal zone

4. benthic zone

thermal stratification

layers:

• epilimnion: warm, top

• thermocline: rapid temp change

• hypolimnion: cold, bottom

• affects O2 distribution

littoral zone

• near shore

• shallow

• lots of light

• high biodiversity

• plants & animals

limnetic zone

• open H2O

• sunlight present

• phytoplankton dominant

profundal zone

• deep H2O

• little/no light

• low photosynthesis

benthic zone

• bottom of lake

• decomposers

• nutrient recycling

rivers & streams

• key characteristics: flowing H2O (current)

• changes from source → mouth

• source (headwaters):

  • cold

  • fast

  • high O2

  • low nutrients

• middle:

  • warmer

  • slower

  • more nutrients

• mouth

  • slowest

  • warm

  • high nutrients

  • low O2

adaptations in rivers & streams

• organisms adapted to current

• fish streamlined

• plants anchored

aquatic/marine: wetlands

areas w shallow H2O that flows slowly over lands that border other bodies of H2O

• includes: bogs, swamps, marshes, estuaries

• bogs are the only ones that MUST be freshwater

what is often called the “kidneys of the world”

• wetlands

• important for H2O purification, stabilization of coastlines, storm/flood protection

• extremely threatened by humans

marine

high salt concentration

oceans

• large, continuous body of salt H2O

• cover 70% of earths surface

marine, coastal regions

• shallow marine environments along the edge of continents

• stretches from the shoreline to the continental shelf

  • there is a sharp drop in depth (open ocean)

• known for extremely high biodiversity

  • high light, high nutrients

  • ex: coral reefs

marine, pelagic regions

• portions of the ocean past the continental shelf

• aka, open ocean

• biodiversity tends to be extremely spread out & greatly dependent on available nutrients

  • could go hundreds of miles w out encountering any macroscopic life

marine, abyssal regions

• deepest portions of the oceans where light cannot penetrate

• approximately 1,000m below the surface of the water

• completely dark

• a lot of animals produce their own light (bioluminescence)