Ground Rules, exams, etc. (no

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First Exam Thursday, 13 February Covers
Chapters 1-4, 6-7 plus Chapter 16 And first 8
lectures plus 6 Readings
Scientific Methods Natural Selection Human
Instincts Our Hunter-Gatherer Heritage Population
Growth Evolutions Problem Gamblers
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The Interface between Climate and
Vegetation Plant Life Forms and
Biomes Tundra Taiga (northern coniferous
forest, spruce forest) Temperate Deciduous
forest Temperate Rain forest Tropical Rain
forest Tropical Deciduous forest Tropical Scrub
forest Temperate grassland and
savanna Chaparral Desert (warm,
cold) Mountains (complex zonation)
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Daily March of Temperature
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Idealized Thermal Profile
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Temperature profiles in a growing cornfield at
midday.
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Microhabitats Leaves droop(wilt) which reduces
solar heat load Leaves in shade present their
full surface to collect as much incoming solar
radiation as possible. Similarly, desert lizards
position themselves perpendicular to the suns
rays in early morning, when environmental
temperatures are low, but during the high
temperatures of midday, these same lizards reduce
their heat load by climbing up off the ground
into cooler air, facing directly into the sun,
thereby reducing heat gained.
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Microhabitat SelectionPlants buffer
temperatures and humidities for animals (also
wind). An aphid lives in a 2mm thick microhabitat
with 100 humidity. Soils act similarly
temperature and moisture content are more stable
deeper down.Wind operates to increase thermal
exchange (wind chill effect) and also has a
desiccating effect.
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Wind Velocities
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Potential Evapotranspiration
(PET)theoretical temperature-dependentamount of
water that could be cookedout of an ecological
system, given itsinput of solar energy and
provided that much water fell on the areaActual
Evapotranspiration (AET)reverse of rain
actual amount of water returned to the
atmosphere(always less than or equal to PET)
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During a period of water surplus, some water may
be stored by plants and some may accumulate in
the soil as soil moisture, depending on runoff
and the capacity of soils to hold water during a
later water deficit, such stored water can be
used by plants and released back into the
atmosphere. Winter rain is generally much less
effective than summer rain because of the reduced
activity (or complete inactivity) of plants in
winter indeed, two areas with the same annual
march of temperature and total annual
precipitation may differ greatly in the types of
plants they support and in their productivity as
a result of their seasonal patterns of
precipitation. An area receiving about 50 cm of
precipitation annually supports either a
grassland vegetation or chaparral, depending on
whether the precipitation falls in summer or
winter, respectively.
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6 CO2 12 H2O gt C6H12O6 6 O2 6 H2O
carbon dioxide CO2 fairly constant
at about 0.03 - 0.04 percent of air
(anthropogenic increase) (CO2 seldom
limits the rate of photosynthesis, usually
it is limited by availability of either light or
water)
water gt Glucose oxygen water
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Net Primary Productivity and World Net Primary
Production for Major Ecosystems
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Net Primary Productivity per Unit
Area (dry g/m2/yr) World Net
Primary
Area Normal
Production (106 km2) Range Mean
(109 dry tons/yr)______________________________
__________________________________________________
__

Lake and stream 2 1001500
500 1.0Swamp and marsh 2 8004000 2000 4.0
Tropical forest 20 10005000 2000 40.0
Temperate forest 18 6002500 1300
23.4Boreal forest 12 4002000 800 9.6
Woodland and shrubland 7 2001200 600
4.2Savanna 15 2002000 700 10.5Temperate
grassland 9 1501500 500 4.5Tundra and
alpine 8 10400 140 1.1Desert scrub 18
10250 70 1.3Extreme desert, rock, ice 24
010 3 0.07Agricultural land
14 1004000 650 9.1Total land 149 730
109.0Open ocean 332 2400 125
41.5Continental shelf 27 200600 350
9.5Attached algae, estuaries 2 5004000 2000
4.0Total ocean 361 155 55.0Total for
earth 510 320 164.0______________________
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Limiting Factors
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Primary Productivity versus Average Annual
Precipitation
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Pedogenic Factors Climate Time Topography Orga
nisms (especially vegetation) Parent materials
Vasily V. Dokuchaev
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Soil Horizons
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Tropical soilsLitter fall high, but decomposes
rapidlyHigh rainfall leaches out water soluble
nutrientsNutrient poor soils cannot sustain
agricultureSlash and burn, move on
strategySecondary succession on mature
soilsRapidly growing colonizing species give way
to slow growing, shade tolerant, climax species
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One to one correspondence between climate,
vegetation, and soils
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Serpentine soils form over serpentine rock.Rich
in magnesium, chromium, and nickel.Contain
little calcium, nitrogen, or phosphorus.Support
a stunted vegetation (low productivity)Introduce
d Mediterranean weeds in CaliforniaPrimary
succession is the development of soils from bare
rock, a slow process that takes centuries.
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Ecotones
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Thermal Stratification
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Bathythermographs High Specific Heat of
Water Heaviest at 4 C ( ice floats ) Eutrophic
Lakes Oligotrophic Lakes Isothermal at Spring
and Fall Turnover