Variation in the Physical Environment Biomes

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What drives large-scale patterns of
environmental variation? Climate 1. Light 2.
Temperature 3. Precipitation 4. Wind Ocean
circulation Geology (soils) Climate
oscillations (2 examples with relevance to
PNW) 1. El nino 2. Pacific Decadal Oscillation
(PDO) How do we characterize broad ecological
patterns? Biomes-based on common vegetation
patterns for a given climate (temp, precip)
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• Some basics and some ecological effects
• The rotation of the Earth around its axis causes
  daily periodicity (day vs. night)
• Circadian rhythms, individual behavior
  (diurnal/nocturnal/crepuscular)
• The rotation of the moon around the Earth causes
  lunar cycles (tides)
• Intertidal zonation, individual behavior
  (movement, feeding, etc.)
• The revolution of the Earth around the sun
  combined with the tilted axis (23.5) causes
  seasonal patterns by hemisphere.
• Annual allocation of activity and energy
  (hibernation, leaf-fall, migration)

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Light
Tilt 23.5
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Electromagnetic Radiation
Photosynthetically Active Radiation

• Photons expressed as energy (Joules), wavelength
  (distance between peaks, nanometers), or
  frequency (time per cycle, hertz).
• Light is what we call wavelengths sensed by the
  human eye (400-700 nm)but really everything
  radio waves, light, and x-rays are all the same
  entity.

heat
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• Latitudinal pattern solar heating decreases away
  from the equator (latitude) as sunlight is spread
  across larger areas
• But un-even heating due to distribution of land
  masses

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Precipitation

• Solar heating causes air to rise
• Rising air cools, and moisture condenses
  (precipitation)
• why you see your breath when air temp is cold
  and not when its hot
• Hadley cells span 30 degrees latitude as air
  descends, it warms and evaporates water
• Deserts occur at latitudes of ______
• Tropical rainforests occur at latitudes of ______

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Figure 4.4
Latitudinal variation in precipitation
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Similar patterns can occur across Longitude
Rain Shadow
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Winds

• Air lags behind the rotation of the earth,
  lagging more where the earth spins faster (low
  latitudes)
• Generally
• High latitudes westerlies (from the west)
• Mid latitudes strong trade winds (NE or SE)
• Equator little to no wind (aka doldrums)

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Latitudinal variation in precipitation
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Doldrums Inter-tropical convergence zone
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Ocean currents

• Water currents generally mimic wind patterns
• Surface water moving offshore causes upwelling
  deep-water nutrients into photic (light) zone
• Ocean moderates climate (specific heat of water
  very high)

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details and names of currents not important
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ENSO

• El Ninoabnormal warming of E. tropical Pacific.
• Southern OscillationEast?West pressure
  difference in tropical Pacific
• La Ninaabnormal cooling of E. tropical Pacific
• GLOBAL CLIMATIC REPERCUSSIONS
• First noted off Peruvian Coast-
• Warm surface water, depressed fish catches,
  seabird declines, high rainfall in coastal desert
• 2-7 years between events (increasing frequency?)
• Tracked by
• Deviations from long-term average sea surface
  temperatures (SST)
• southern oscillation index (SOI) composite
  index of sea surface temps, atmospheric pressure,
  prevailing wind
• Examples
• Snowfall at Mt. Baker (during what years should I
  buy a seasons pass?)
• Galapagos Finches (classic Darwinian selection)

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Large-scale climate cycles
El nino
El Niño-Southern Oscillation (ENSO)
Pacific Decadal Oscillation (PDO)
El Niño
warm
La Niña
cold
http//tao.atmos.washington.edu/
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Ocean circulation and upwelling effects
Normal
ENSO
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Climate Effects of El Nino
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Galapagos Islands vegetation
La nina winter 1982
El nino winter 1983
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from Darwins journal 1835
Selection pressure for large beaks released (or
different) in El nino or normal years
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PDO

• Pacific Decadal Oscillationslower but cyclic
  changes in dominant climate features of the North
  Pacific
• SST, pressure, circulation, winds
• Affects ocean temperatures and productivity
• Warm and Cool periods
• 20-30 years between regime shifts
• Examples
• Alaska and Pacific NW salmon returns (Mantua et
  al. 1997)

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Large-scale climate cycles
El Niño-Southern Oscillation (ENSO)
Pacific Decadal Oscillation (PDO)
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El Niño
2
1
0
Std Devs SST
-1
La Niña
-2
-3
-4
1900
1910
1920
1930
1940
1950
1960
1970
1980
1990
2000
Year
http//tao.atmos.washington.edu/
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PDO and salmon catches
Annual catch in millions of fish
Mantua, N.J. et al. 1997. Bulletin American
Meteorological Society 781069-1079
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What drives large-scale patterns of
environmental variation? Climate 1. Light 2.
Temperature 3. Precipitation 4. Wind Ocean
circulation Geology (soils) Climate
oscillations (2 examples with relevance to
PNW) 1. El nino 2. Pacific Decadal Oscillation
(PDO) How do we characterize broad ecological
patterns? Biomes
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Physical characteristics of the environment
affect organismsdrive adaptations in
physiology, behavior, etc.

• Light
• Temperature
• Nutrients
• Water availability
• Temperature
• Carbon dioxide (plants)
• Oxygen (animals)

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Characterizing broad ecological patterns

• BIOMES
• classifies terrestrial systems according to
  similarity in climate
• similar climates tend to have organisms with
  similar adaptations to that climate
  (parallel/convergent)
• Based 1 on the composition of terrestrial plant
  communities (temperature precipitation as key
  factors)
• Whittakers biome classification average
  temperature vs. average precipitation
• Aquatic
• Biome classification not specifically aquatic,
  but still useful as it reflects differences in
  major climate features important for terrestrial
  and aquatic organisms alike

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Major Biomes
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How might these patterns change with climate
oscillations (ENSO, PDO) or long-term climate
change?
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