Ecology: Lecture 2Ecology: Lecture 2
Biomes as related to Biomes as related to Temperature and MoistureTemperature and Moisture
Global distribution of Global distribution of terrestrial biomesterrestrial biomes
What causes the poles to be colder What causes the poles to be colder than equatorial regions?than equatorial regions?
Key reason: Curvature of the earth and resultant angle of sun’s rays [Fig. 2.7a]
Which other factors mediate the Which other factors mediate the distribution of global distribution of global
temperature?temperature? Earth’s rotation air and ocean
currents that affect the distribution of heat energy
Earth’s tilt (angle of axis) Albedo
Movement of air massesMovement of air masses
If the earth had no rotation:
Movement of air massesMovement of air masses With rotation:
Ocean circulation Ocean circulation patterns and heat patterns and heat
distributiondistribution Example: Effect of the Gulf Stream on
temperatures (E. North America; W. Europe)
The angle of the earth’s axis is responsible for seasonal variations on the earth.
Fig. 50.12
Copyright © 2002 Pearson Education, Inc., publishing as Benjamin Cummings
Position shifts between summer and winter (why?)
Albedo: Albedo: reflectance of reflectance of solar radiationsolar radiation
Snow and Ice: high albedo
(Photo: K. Haberman) Forested areas:
low albedo Photo: Natl. Park Svc.
Global patterns of precipitationGlobal patterns of precipitation
Global patterns of precipitationGlobal patterns of precipitation Warm air holds more moisture than cold air Warm air rises and cools, dropping moisture close to
where it was picked up, so that moist areas tend to remain moist, and dry areas tend to remain dry
Warm, dry air picks up additional moisture…
Altitude and Rain Altitude and Rain shadowsshadows
North vs. south facing North vs. south facing slopesslopes
North vs. south facing slopes (cont.)North vs. south facing slopes (cont.)
MicroclimateMicroclimate example: example: Effects of vegetation on Effects of vegetation on
temperature temperature
NutrientsNutrients Macronutrients
Definition? Examples: C, H, N, O, P, Ca, Mg, K, S, Na,
Cl Micronutrients
Definition? Examples: Fe, Mn, B, Co, Cu, Mo, Zn, I,
Se
Global distribution of Global distribution of productivity in the oceanproductivity in the ocean
UpwellingUpwelling
Focus on lightFocus on light Characteristics that vary with
climate/microclimate wavelength intensity duration directionality
Light energy as a Light energy as a function of latitude and function of latitude and
time of yeartime of year
PAR: Photosynthetically PAR: Photosynthetically active radiation (400-740 active radiation (400-740
nm)nm)
Attenuation of light Attenuation of light through waterthrough water
Attenuation of light Attenuation of light through vegetationthrough vegetation
Leaf area index
Attenuation of light Attenuation of light through vegetation through vegetation
(cont.)(cont.)
Other key factorsOther key factors Salinity
Example: Different estuarine species are tolerant to different conditions
Oxygen concentration Example 1: Surface waters vs.
sediments in an estuary pH Substrate (i.e. soil type, rocky
vs. muddy river bottom, etc…) Example: Distribution of
macroinvertebrates in streams.
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