Environments

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Chapter 4

• Environments
• and Life

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What is your current classification?

• Freshman
• Sophomore
• Junior
• Senior

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Guiding Questions

• What factors determine the ecological niches of
  species, and by what means do species obtain
  nutrition?
• What factors govern the geographic distribution
  of species?
• What factors govern the distribution of aquatic
  life?

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Environmental Differences

• Tropical vs Polar - Terrestrial and Marine
• Low vs High Elevation
• Shallow vs Deep
• Wet vs Dry

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Hypsometric Curve

• Curve showing the proportions of the Earths
  surface above and below sea level

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Hypsometric Curve
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Climate

• Climate
• Controls distribution of species globally
• Has changed through time
• Plate tectonics and other changes affect climate

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Ecology

• Ecology
• Study of the factors that govern the distribution
  and abundance of organisms in natural
  environments
• Habitats
• Environments on or close to Earths surface
  inhabited by life
• Terrestrial
• Aquatic
• Marine
• Freshwater

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Ecology

• Ecologic niche
• The way a species relates to its environment,
  including food, nutrients, physical and chemical
  conditions
• Life habit
• The way a species lives within its niche
• Limiting factors
• Naturally occurring, restricting condition
  (physical and chemical)
• Competition
• Shared drive for limited resources
• Predation

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Competition

• Arises because organisms share space
• Predation also comes in here by possibly limiting
  or preventing another species from inhabiting a
  particular environment.

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Ecosystem

• Ecosystem
• Organisms of a community and the physical
  environment they occupy
• Population
• Group of individuals that belong to a single
  species and live together in a particular area

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Ecosystem

• Ecologic community
• Populations of several species living in a
  habitat
• Producers
• Photosynthesizing organisms foundation of
  community
• Consumers
• Herbivores feed on producers
• Carnivores feed on other consumers

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Ecosystem

• Biota
• Fauna animals and protozoans of an ecosystem
• Flora plants and plantlike protists
• Food chain
• Sequence of consumption for producers to consumers

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Food Web

• Food web
• More complex than simple food chain
• More common
• Several species occupy each level

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Ecosystem

• Parasites
• Feed on living organisms
• Scavengers
• Feed on organisms that are already dead

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Ecology
The movement of materials through an ecosystem.
Components within ovals are consumers.
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Figure 4-35 (p. 134)Interdependence of
photosynthesis and respiration.
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Figure 4-38 (p. 136)Simple pyramid of ocean
life.
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Biogeography

• The distribution and abundance of organisms on a
  broad geographic scale.

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Biogeography

• Temperature
• Moisture
• Nutrients

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Ecosystem

• Diversity
• The variety of species that live together within
  a community
• Lower in more difficult habitats
• Predation influences diversity
• Heavy can reduce diversity
• Moderate can increase diversity by reducing
  competition
• Opportunistic species
• Species that specialize in invading newly vacated
  habitats

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Biogeography

• Distribution and abundance of organisms on a
  broad geographic scale
• Limiting factors
• Diversity increases toward equator
• Barriers can affect dispersal

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Life Habitats

• The mode by which an organism lives, feeds in an
  environment
• 1. Tropical vs. Polar
• 2. Low vs high altitude
• 3. Shallow vs deep
• 4. Benthic vs. Planktonic

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Atmosphere

• Regulates Earths temperature (-18C w/o
  atmosphere)
• Composition
• N2, O2, CO2
• Tilt of the Earth affects solar insulation,
  temperature, and climate

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In our present atmosphere, concentrations of O2
and CO2 are

• O2 gt CO2
• O2 lt CO2
• O2 CO2

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The Atmosphere

• Nitrogen -78
• Oxygen - 21
• Carbon dioxide (CO2 ) - 0.037 or 370 ppm
• Methane (CH4) - 0.00018 or 1800 ppb

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Solar Radiation

• Daylight
• Which receives more hours of daylight?
• Equator vs Poles
• The amount of daylight ( of hours) averaged over
  a year is the same at the poles as at the equator

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Solar Radiation
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Solar Radiation

• Temperature difference is due to the angle of the
  sunlight and the albedo
• In the high latitudes, the sun hits at a low
  angle and therefore the unit energy of sunlight
  is spread over a large cross-sectional area of
  the earths surface. In the tropics, the sun
  hits directly and therefore is much more
  concentrated

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Solar Radiation
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Solar Radiation

• Albedo refers to the reflectivity of the Earths
  surface
• 1. Snow and ice is very reflective - much of the
  solar radiation is reflected by to the solar
  system
• 2. Water has a low albedo and absorbs a lot of
  the solar radiation

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Solar Radiation
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Solar Radiation
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Solar Radiation

• When do we have summers?
• True or False
• Summers on Earth occur when it passes closest to
  the Sun

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Solar Radiation

• Obliquity or Tilt (23.5) of the to Earths
  rotational axis
• This tilt gives us seasons. Summer is when the
  northern or southern hemisphere is point towards
  the Sun

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Atmosphere

• Regulates Earths temperature
• Composition
• N2, O2, CO2
• Tilt of the Earth affects solar insulation,
  temperature, and climate

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Solar RadiationHeat Capacity
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Movement of Air mass

• Rises at Eq. and sinks near Poles
• The high solar radiation at the equator heats the
  air masses, causing them to rise (buoyant).
• As the air rises, the temperature of the air mass
  decreases

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Atmospheric Circulation

• Net transport
• Air sinks at the poles, rises at the equator
• Simplified model
• No tilt
• No Coriolis effect

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Rising Air

• As the air rises, the temperature of the air mass
  decreases (adiabatic lapse rate 5C/km)
• Cold air holds less water vapor. Voila, rain and
  the tropical rainforest. Low pressure systems
  usually have rain because the rising air drop
  water as the air ascends and cools

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Rising Air
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Atmospheric Circulation

• Coriolis effect
• Earths rotation causes air and water masses to
  be defected to the right (clockwise) in the
  northern hemisphere
• Counterclockwise for southern hemisphere

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Atmospheric Circulation

• If we reverse the direction and launch a rocket
  from Panama towards Washington DC, which way will
  it curve?
• A Right
• B Left
• C Not at all because Panama is close to the Eq.

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Coriolis force

• Deflection of moving objects to the right in the
  No. Hemisphere and left in the So. Hemisphere

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Coriolis Force
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Atmospheric Circulation

• Actual pattern is more complex
• Three circulation cells
• Trade winds, westerlies, easterlies
• Intertropical convergence zone
• Northern, southern trade winds converge near
  equator
• Changes seasonally

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Temperature Variations

• Atmosphere retains heat
• Solar radiation
• Absorbed and turned into heat energy
• Reflected
• 6-10 ocean
• 5-30 forest
• 45-95 ice and snow

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Trade winds

• As the dry air descending around 30 begins to
  flow back towards the Eq. it is deflected to the
  right.

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Trade windsAs the dry air descending around 30
begins to flow back towards the Eq. it is
deflected to the right.
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Trade windsThe NE and SE trades converge on the
latitude where the maximum in convection (rising
air) is occurring. This is the warmest location.
Today, this is between 4 and 10N and is termed
the Inter-Tropical Convergence Zone (ITCZ)
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The Terrestrial Realm

• Latitudinal Zones and Vegetation
• Rain forests
• Deserts
• Savannah Grasslands
• Temperate Forest
• Conifer or Evergreen Forest
• Tundra

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Terrestrial Realm

• Vegetation follows climatic zone
• Tropical rain forest
• Desert savannahs
• Temperate forests
• Polar tundra

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Terrestrial Realm

• Tropical Climates
• 1820 C (6468 F)
• 030 latitude
• Tropical Rain Forest
• Dense vegetation

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Rain forests

• develop under the tropical low pressure systems.
  Rising air dumps lots of rain. Found within a few
  degrees near the equator

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Terrestrial Realm

• Deserts
• Dry trade winds remove moisture
• 2030 north and south of the equator
• lt 25 cm rain/year
• Little vegetation
• Savannah, grasslands
• Too dry to support forests

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Deserts

• (lt10 inches of water per year) develop under the
  sinking dry air masses and under the dry Trade
  Winds. Usually found around 30 latitude.

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Savannah Grasslands

• found between Rain forest and Desert and receive
  seasonal rain falls. Not enough rain throughout
  the year to support woodland

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Tundra

• - Arctic ecosystem where layer beneath soil
  remains frozen throughout the year.

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Terrestrial Realm

• Poles
• Defined by ice sheets and glaciers today
• Absent or reduced at times in the past

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Terrestrial Realm

• Glaciers
• Ice in motion
• Glide and spread
• Present at high latitudes and high elevations
  near equator

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Terrestrial Realm

• Tundra
• Limited water
• Grasses, sedges, lichens, shrubs dominate
• Cannot support tall trees
• Evergreen coniferous forests
• South of tundra
• Spruce, pine, fir

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Terrestrial Realm

• Temperate forests
• Longer summers, slightly warmer
• Deciduous trees
• Maples, oaks, beeches
• Mediterranean climate
• Dry summers, wet winters
• Common 40 N and S of equator
• Californian, Mediterranean region

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Climate

• Altitude
• Similar to latitudinal gradient
• At base
• Deciduous forest
• On slopes
• Evergreen forest
• Tundra above tree-line
• At top
• Glaciers

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Climate

• Mountains
• Rain shadow
• Prevailing winds bring moisture
• Precipitation on windward side
• Aridity on leeward side
• Rain shadows common on east side of North
  American mountain chains

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Climate

• Seasonal Change
• High heat capacity of water
• Less change in ocean temperatures than on land
• Monsoon Circulation
• Summer winds flow onshore bring rain
• Winter winds offshore

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Plants as Climate Indicators

• Sensitive indicators of change
• Cycads
• Tropics and subtropics today
• Fossil distribution allows reconstruction of
  climate patterns

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Plants as Climate Indicators

• Leaf Margins
• Tropics
• Smooth, waxy margins
• Temperate climates
• Jagged margins

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Marine Realm

• Ocean currents
• Wind driven
• Follow atmospheric patterns
• Trade winds
• Push waters west form equatorial currents
• Equatorial countercurrents
• Return flow
• Gyres
• Clockwise in Northern Hemisphere
• Gulf Stream

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Marine Realm

• Circumpolar current
• Circles Antarctica
• Very cold

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Marine Realm

• Polar circulation
• Sea ice leads to more saline water
• Cold, dense waters sink
• Antarctic waters
• Flow north at depth
• Arctic waters
• Flow south at depth

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Marine Realm

• Ocean circulation
• Waves
• Surface waves
• Wind driven
• Break when seafloor interacts at shallow depths
• Tides
• Cause major movement of water in oceans
• Due to rotation of solid Earth beneath bulges of
  water produced by gravitational attraction of the
  moon

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Marine Realm

• Continental Shelf
• Submarine extension of continental landmass
• Shelf break
• Edge of shelf
• 200 m w.d.
• Continental Slope
• Continental Rise
• Abyssal Plain

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Figure 4-31 (p. 131)Classification of marine
environments. (After Hedgspeth, UJ. W., ed.
1957. Treatise of Marine Ecology and
Paleoecology. Geological Society of America
Memoirs 67(1) 18.)
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The Marine Realm

• The depth of the Sea
• Moving from the beach seaward, one crosses a
  consistent pattern of water depth changes. The
  continental shelf extends from the shoreline to
  the continental shelf break. Water depths over
  the shelf vary from 0 to 200 m. This
  environment is very important for benthic
  communities because the photic zone in the ocean
  extends only down to 200m. Consider the
  implications for primary production

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The Marine Realm

• The Shelf break marks the distal edge of the
  shelf where seaward of this point, water depths
  increase at a greater rate (3 to 5slope)
  compared with the shelf (1 to 2slope).

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The Marine Realm

• Continental Slope.
• Typically, the slope extends down to 3000 to 3500
  m. Near the base of the slope is the transition
  from continental to oceanic crust.

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The Marine Realm

• The Slope gives way to the Continental Rise.
  This is a less steep surface that segways to the
  Abyssal Plain (the ocean floor). The Rise is
  created as sediments are transported down the
  slope in turbidity currents.

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The Marine Realm

• At the base of the slope and out on the abyssal
  plain, the slope decreases significantly and the
  sediments are dropped, forming the Rise

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Figure 4-31 (p. 131)Classification of marine
environments. (After Hedgspeth, UJ. W., ed.
1957. Treatise of Marine Ecology and
Paleoecology. Geological Society of America
Memoirs 67(1) 18.)
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Marine Realm

• Near shore
• Barrier islands
• Marshes
• Epicontinental seas

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Marine Realm

• Photic Zone
• Region of ocean where enough light penetrates to
  permit photosynthesis
• Pelagic life
• Plankton
• Phytoplankton
• Zooplankton
• Nekton
• Benthic life
• Suspension feeders
• Deposit feeders

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Marine Realm

• Marine Biogeography
• Tropical
• Subtropical
• Transitional
• Subarctic

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Figure 4-36 (p. 135)Major ocean surface
currents.
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Marine Realm

• Corals
• Most require warm water
• Common in tropics
• Reef builders
• Coral polyp
• Builds coral cup
• Connected to other polyps
• Symbiotic relationship with algae

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Marine Realm

• Salinity
• Limiting factor near shore
• Oceanic
• 35 ppt
• Brackish
• Lower than marine
• Bays, lagoons
• Hypersaline
• Higher than marine
• Hot arid climates

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The portion of the temperature-depth curve in the
ocean that shows maximum change is the
thermocline.
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Deep Water Circulation
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Atmospheric Circulation

• If we reverse the direction and launch a rocket
  from Panama towards Washington DC, which way will
  it curve?
• A Right
• B Left
• C Not at all because Panama is close to the Eq.