Ecology: Lecture 2

Biomes as related to Temperature and Moisture

Global distribution of terrestrial biomes

What causes the poles to be colder than equatorial regions?  Key reason: Curvature of the earth and resultant angle of sun’s rays [Fig. 2.7a]

Which other factors mediate the distribution of global 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 masses  If the earth had no rotation:

Movement of air masses  With rotation:

Ocean circulation patterns and heat distribution  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 Copyright © 2002 Pearson Education, Inc., publishing as Benjamin Cummings

 Position shifts between summer and winter (why?)

Albedo: reflectance of solar radiation  Snow and Ice: high albedo  (Photo: K. Haberman)   Forested areas: low albedo   Photo: Natl. Park Svc.

Global 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 shadows

North vs. south facing slopes

North vs. south facing slopes (cont.)

Microclimate example: Effects of vegetation on temperature

Nutrients  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 productivity in the ocean

Upwelling

Focus on light  Characteristics that vary with climate/microclimate  wavelength  intensity  duration  directionality

Light energy as a function of latitude and time of year

PAR: Photosynthetically active radiation ( nm)

Attenuation of light through water

Attenuation of light through vegetation  Leaf area index

Attenuation of light through vegetation (cont.)

Other 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.