BIOL 4120: Principles of Ecology
Lecture 4: Adaptation to
Physical Environment: Climate,
Water, and Soil
Dafeng Hui
Office: Harned Hall 320
Phone: 963-5777
Email: dhui@tnstate.edu
Topics:
4.1 Global patterns in temperature and
precipitation are established by solar radiation
4.2 Ocean currents redistribute heat
4.3 Seasonal variation in climate
4.4 Changes in water density drive seasonal
cycles in temperate lakes
4.5 Climate and weather undergo irregular and
often unpredicted changes
4.6 Topographic features cause local variation in
climate
4.7 Climate and soil
4.1 Global patterns in temperature and
precipitation are established by solar
radiation
Tropic of Cancer (latitude 23.5ºN), & Tropic of Capricorn (23.5ºS) defined by
extreme latitudes at which sun is directly overhead annually--summer &
winter solstice, respectively. This corresponds with 23.5º angle of tilt of
Earth. Thus “solar equator” (region of maximum solar input) moves relative
to latitude seasonally.
Tilt of the earth’s axis causes seasonal
variation in climate
Autumnal Equinox
Vernal Equinox
Tropic of Capricorn
of Cancer
The distribution of solar energy with respect to
latitude
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Compare a
temperate region
with a tropical
region
Much greater
variation in
temperate region
Poles are not
included but see
high altitude
Energy input to
atmosphere & Earth’s
surface via solar
radiation drives the
annual T: maximal at
equator, & declines to
40% of maximal
values at high
latitudes.
Temperature influences
moisture content of air
Evaporation: liquid to vapor
Condensation: from water
vapor to liquid
Vapor pressure: amount of
pressure water vapor exerts
independent of pressure of
dry air.
Saturated vapor pressure:
vapor pressure of air at
saturation (Equilibrium VP).
Absolute humidity; amount
of water in a given volume
of air.
Relative humidity: RH
3.3 Air masses circulate globally
The blanket of air surrounds the planet
– atmosphere – is not static
It is in a constant state of movement,
driven by the rising and sinking of air
masses and the rotation of the Earth
on its axis.
Coriolis effect:
Deflection in the pattern of air
flow.
Clockwise movement in N
hemisphere, counterclockwise in
S. Hemisphere.
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Three cells and trade
wind belts
These air movements
create global precipitation
pattern
Major latitudinal displacements of surface air currents: convection currents drive
Hadley cells, pulling air at surface into Inter-Tropical Convergence Zone, ITCZ);
Ferrel Cells driven by low pressure zone at 20º-30º lat.; Midlatitude westerlies
converge into jet stream; polar cells driven by high pressure (cold) flows out of
polar region along Earth’s surface towards south.
Intertropical
convergence
and
subtropical
high-pressure
belt (arid
zone)
4.4 Latitudinal shifting of the sun’s
zenith causes seasonal variation in
precipitation
(e.g., Intertropical Convergence Zone shift)
Shifts of ITCZ
produce
rainy
seasons and
dry seasons
in the tropics
Seasonal climate
patterns differ among
subtropical localities
A: Chihuahuan Desert (summer
rainy season)
B. Sonoran Desert (rainfall in
summer and winter, from Pacific
Ocean)
C. Majave Desert (winter rain,
summer dry: Mediterranean
climate)
4.5 Ocean currents redistribute heat
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Ocean currents also affect climate, sometimes very dramatically
(source of energy movement)
Each ocean is dominated by great circular water movement, or
gyres. Gyres move clockwise in the N. Hemisphere and
counterclockwise in the S. Hemisphere (Coriolis effect).
Warmer water moves away from equator and cold water moves
towards equator.
Upwelling and biological productivity
Thermohaline
circulation
Two layers
Thin warm
layer 18 oC
Deep cold
layer 3 oC
Ocean Water Currents are Determined by Salinity and Temperature
Cold and High Saline Water Sinks and Warm Water Rises
Rising and Sinking of Water Generates Ocean Currents
Ocean Currents Have Huge Impacts on Temperature & Rainfall on Land
This process occurs over hundreds of years
4.6 Temperature-induced changes in water density
drive seasonal cycles in temperate lakes
Turnover of water and
nutrient during spring
and fall
4.7 Climate and weather undergo
irregular and often unpredictable
changes
Irregular variations (Little Ice Age: cooling
between mid-14 to mid-19th century)
(El Nino and La Nina)
El Nino: an abnormal warming of surface ocean
waters in the eastern tropical Pacific.
El Nino-Southern Oscillation (ENSO): An
oscillation in the surface pressure between the
southeastern tropic Pacific and the AustralianIndonesian regions.
Indonesia
Peru
Normal conditions, strong trade winds move surface
water westward. As the surface currents move westward,
the water warms. The warmer water of the western
Pacific causes the moist maritime air to rise and cool,
bringing abundant rainfall to the region;
Indonesia
Peru
ENSO: Trade winds slacken, reducing the westward
flow of the surface currents. Rainfall follows the warm
water eastward, with associated flooding in Peru and
drought in Indonesia and Australia.
La Nina: injection of cold water becomes
more intense than usual, causing the
surface of eastern Pacific to cool. Results
in droughts in South America and heavy
rainfall in Australia.
Values below
0 are El Nino
years
Zimbabwe
Area affected by ENSO in one typical El Nino year in Zimbabwe (Dry
and warm)
4.8 Topography influences regional
and local patterns of precipitation
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Rain shadow:
Maui, Hawaiian Islands.
10 oN
Many trees in the rain
shadow on the Pacific
slope of Panama shed
their leaves during
the dry season
4.8 Microclimates
Microclimates defines the local, small
scale conditions in which organisms live.
These conditions include: topography
(aspect=direction a slope face, surface or
underground, beneath vegetation or not),
light, temperature, air conditions or wind
movement, moisture etc.
Vegetation also moderate microclimates.
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Most organisms exist in a microclimate
that is optimal
Scale of climate in hundreds of kilometers
Scale of microclimate can vary from
meters to kilometers to tens of kilometers
San Gabriel
Mountains, near Los
Angeles, CA.
North facing slope(
left): pine-oak forest
South facing slope
(right): droughtresistant chaparral
vegetation.
Life zones along mountain slope
due to adiabatic cooling (6oC/1km)
Vegetation changes with increasing elevation in the mountains of Arizona
Saguaro catus->Agave and grasses  Oaks and grasses ponderosa pine
spurce and fir  bushes, willows, herbs and lichens (above tree lines)
BIOL 4120: Principles of Ecology
Lecture 4: Adaptation to
Physical Environment: Climate,
Water, and Soil
Dafeng Hui
Office: Harned Hall 320
Phone: 963-5777
Email: dhui@tnstate.edu
Recap:
Ocean currents redistribute heat
Water cycling in temperate lakes
Irregular and often unpredicted changes
Local climate and microclimate
Climate and soil
4.9 Climate and the underlying
bedrock interact to diversify soils
Soil profile
Layers or
horizons
4.10 Basic Soil Formation Processes
Produce Different Soils
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Regional differences in geology, climate,
and vegetation give rise to
characteristically different soils
Weathering is a process that soils are
formed
Five factors influencing weathering
process: climate, parent material,
vegetation, local topography, and age
The broadest level of soil classification is
soil order
There are twelve orders of soil
•
•
•
•
•
•
Entisol
Mollisol
Alfisol
Andisol
Aridisol
Inceptisol
•
•
•
•
•
•
Histosol
Oxisol
Vertisol
Spodosol
Ultisol
Gelisol
Ultisol (Laterization)
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Ultisol
• Warm climate soil
• Redish or yellowish
• Low nutrient content
Laterization:
when PPT greatly exceeds ET in warm climates,
water rapidly percolated through soil and into groundwater.
Soluble soil nutrients are constantly leached out of soils, leaving
behind the less soluble ions (Al+++ and Fe++) which give soil
color (whitish for Al and red for Fe) and H+ make soil acidic and
nutrient poor.
Highly oxidized and deeply weathered soils in West
Tennessee.
Aridisol (Salinization)
Salinization:
in very dry
climates and when loss of soil
moisture due to ET exceeds
PPT, water leaves the soil
through the surface. The
minerals (NaCl) dissolved
move upward from the
groundwater and result in a
salt crust on the surface of
the soil.
Irrigation of dryland can result
salinization. This becomes a
problem in US southwest,
Australia, Northern Africa,
China, and major areas of
dryland irrigation.
Spodosols (Podsolization)
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Spodosols
• Cool moist regions
• Acid, shallow leaching
horizon
• Deep layer of
deposition, lower soil
fertility
Podsolization: In acidic
soils in cool moist regions of
the temperate zone, clay
particles break down in the E
horizon and their soluble
irons are transported
downward and deposited in
the lower B horizon, reduce
the fertility of the upper layer
of the soil.
The End