Global Ecology

Biosphere

• Sum total of places in which organisms live

• Encompasses the entire earth

• The distribution of organisms (biogeography)
  is affected by:

  • Geologic history

  • Topography

  • Climate

  • Other species

Biomes

• a region of land characterized by habitat conditions and community structure

Climate

• the average weather condition of a region

Latitudinal Impacts on Sunlight

• High latitudes cause a particular ray of sunlight to pass through more atmosphere and is distributed over a wider land area than other rays of sunlight at lower latitudes

• Tropical regions receive two and a half times as much solar radiation as polar regions

Climate Factors

• Solar radiation

• Seasonality

• Air flow

• Precipitation

• Ocean currents

Higher Latitude

• experiences more extreme seasonal variations

Opposite Hemispheres

• experience opposite seasonal variations

Summer Solstice

• Northern hemisphere is most tilted toward sun; has it’s longest day

Autumn Equinox

• Sun’s direct rays fall on equator; length of day equals length of night

Winter Solstice

• Northern Hemisphere is most tilted away from sun; has it’s shortest day

Spring Equinox

• Sun’s direct rays fall on equator fall on equator; length of day equals length of night

Global Air Circulation Patterns (Northern Hemisphere)

• At 0 degrees, Warm, moist air cools as it rises, causing rainfall

• Around 30 degrees latitude, some of the cool, dry air sinks, and is then deflected both North and South

• As air travels north, it warms and rises. The clash of moist, warm air and cold polar fronts produces rain at about 60 degrees latitude

• Cool, dry air sinks near the poles

• Patterns are inverted in the Southern Hemisphere

Precipitation

• Solar radiation and air circulation are responsible for global patterns of precipitation

The Coriolis Effect

• An object travelling in the straight line across a rotating path appears to travel in an arc

• Consider points A and B on a rotating record

• Both travel around and arrive at the green line at the same time (same period)

• However, B travels a greater distance and must therefore be moving faster than A

Movement of Air

• Earth’s rotation causes winds to curve east or west

• air circulation established by six giant convection cells

Ocean Currents

• Patterns in air circulation drive surface currents

Coastal Wind Patterns

• Oceans mitigate temperatures

• Breeze blows in direction of warmer region

• direction varies with time of day

Rain Shadows

• Air rises on the windward side, loses moisture before passing over the mountain

Tundra

• Northernmost biome; plants grow in shallow topsoil over a layer of permafrost

• Brief growing season; winter winds cause tundra plants to be very short

Boreal Forests

• Also called the Taiga

• Consists mainly of coniferous forests

Temperate Deciduous

• Grow at middle latitudes with abundant rainfall

• Trees lose their leaves in the winter

Grasslands

• Grows where winters are cold, summers are warm, and rainfall is moderate

Chaparral

• Coastal biome dominated by dense, woody shrubs and trees that resprout after periodic fires

  • Occurs where winters are mild and wet and summers hot and dry

Desserts

• Arid regions low precipitation

Tropical Forests

• High temperatures and precipitation • Species-rich

• Nutrient-poor soil

Aquatic Biomes

• Freshwater –

  • Streams, rivers

  • Lakes

• Ocean

  • Estuaries

  • Coastal

  • Open Ocean

Lakes

• Bodies of standing water that accumulate in basins

• Fed by rainfall and streams and rivers that drain surrounding watersheds

Oligotrophic

• Low in nutrients, high in oxygen

Eutrophic

• Rich in nutrients and organic matter

Oceans

• Estuaries

• Intertidal zones

• open ocean