BIOSPHERE

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Chapter 49

• BIOSPHERE

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• Hot Spots
• Portions of biomes that show the greatest
  biodiversity
• Conservationists are working to inventory and
  protect these regions
• 24 hot spots hold more than half of all
  terrestrial species
• Ecoregions
• Large areas of globally important biomes or water
  provinces
• Currently vulnerable to extinction
• Targeted by World Wildlife Fund for special study
  and conservation efforts

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Soil

• Characteristics determined by
• amount of humus, pH, degree of aeration, ability
  to hold or drain water, and mineral content
• Soil characteristics determine what plants will
  grow and how well.

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Low
Changes in plant form along environmental
gradients
Alpine Tundra
Montane Coniferous Forest
Elevation
Deciduous Forest
Tropical Forest
High
Tropical Forest
Temperate Deciduous Forest
Northern Coniferous Forest
Arctic Tundra
Moisture Availability
Low
High
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Seasonal Variation

• Northern end of Earths axis tilts toward sun in
  June and away in December
• Difference in tilt causes differences in sunlight
  intensity and day length
• The greater the distance from the equator, the
  more pronounced the seasonal changes

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Ocean Currents

• Upper waters move in currents that distribute
  nutrients and affect regional climates

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Monsoons

• A pattern of wind circulation that changes
  seasonally
• Affect continents north and south of warm-water
  oceans
• Can cause seasonal variation in rains

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Coastal Breezes

• Breeze blows in direction of warmer region
• Direction varies with time of day

Night
Afternoon
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Rain Shadow

• Air rises on the windward side, loses moisture
  before passing over the mountain

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Life on Land

• Biomes terrestrial life zones
• Regions of land characterized by habitat
  conditions and community structure
• abundance of oxygen/sunlight
• determined by
• precipitation
• temperature
• geographical altitude
• latitude
• direction (for the angle of insolation)

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Biogeographic Realms

• Six areas in which plants and animals are
  somewhat similar
• Maintain their identity because of climate and
  physical barriers that tend to maintain isolation
  between species

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desert
mountain grassland
mountains, complex zonation
temperate coniferous forest
dry shrubland, dry woodland
tropical broadleaf forest
mangrove swamps
northern coniferous forest
warm grassland
temperate deciduous forest
permanent ice cover
tropical dry forest
tropical coniferous forest
temperate grassland
tundra
marine ecoregions
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Deserts

• Less than 10 centimeters annual rainfall, high
  level of evaporation
• Tend to occur at 30 degrees north and south and
  in rain shadows
• One-third of land surface is arid or semiarid

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Dry Shrublands and Woodlands

• Semiarid regions with cooler, wet winters and
  hot, dry summers
• Tend to occur in western or southern coastal
  regions between latitudes of 30 and 40 degrees

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Forest Biomes

• Tall trees form a continuous canopy
• Evergreen broadleaves in tropical latitudes
• Deciduous broadleaves in most temperate latitudes
• Evergreen conifers at high temperate elevations
  and at high latitudes

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Arctic Tundra

• Occurs at high latitudes
• Permafrost lies beneath surface
• Nutrient cycling is very slow

 Arctic tundra in Russia in summer
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Alpine Tundra

• Occurs at high elevations
• No underlying permafrost
• Plants are low cushions or mats as in Arctic
  tundra

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Life in Water

• Aquatic ecosystem 72 of the Earths surface
• salt water 71
• estuaries, tidepools, open ocean, coral reefs
• fresh water 1
• (Rivers, streams, ponds, lakes, marshes)
• Properties of Water
• less temperature fluctuation
• needs sunlight to maintain life
• more nutrients near the bottom

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Fresh Water Lakes

• Characteristics
• Vary in size, depth, nutrient content
• share common features
• Life Zones
• littoral zone
• limnetic zone
• profundal zone
• Temperature Stratification (thermal layering)
• summer fall spring
• Types oligotrophic/eutrophic

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Streams

• Begin as springs
• or seeps
• Carry nutrients
• downstream
• Solute concentrations influenced by streambed
  composition and human activities

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Marine Ecosystem

• Benthic province the ocean floor
• Intertidal Neritic zone
• Continental shelf Neritic zone, w/ coral reefs
• Bathyal zone Oceanic zone
• Abyssal zone Oceanic zone
• Hadal zone Oceanic zone
• Nutrient supplies beside photosynthesis
• wash off by the river from the land
• upwelling

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Ocean Provinces
neritic zone
oceanic zone
intertidal zone
continental shelf
sunlit water
"twilight" water
0
200
PELAGIC PROVINCE
bathyal shelf
BENTHIC PROVINCE
sunless water
1,000
2,000
abyssal zone
4,000
hadal zone
deep-sea trenches
11,0000 depth (meters)
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• Pelagic province ocean water
• Neritic zone/Oceanic zone
• Euphotic/aphotic layers
• Neritic zone Coastal Waters
• Intertidal zone
• Continental shelf
• Coastal Reefs
• Oceanic zone
• deep-sea vent

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Seasonal Overturn

• In spring and fall, temperatures in the lake
  become more uniform
• Oxygen-rich surface waters mix with deeper
  oxygen-poor layers
• Nutrients that accumulated at bottom are brought
  to the surface

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Primary Productivity

• Primary producers are usually the phytoplankton
• Productivity can vary seasonally

north temperate
north polar
tropical
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Deep Ocean Food Webs

• Regions too dark for photosynthesis
• Marine snow supports a detrital food web
• Organic matter drifts down from shallower water
• Diverse species migrate up and down in water
  column daily

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Hydrothermal Vents

• Openings in ocean floor that spew mineral-rich,
  superheated water
• Primary producers are chemoautotrophic bacteria
  use sulfides as energy source

Tube worms at hydrothermal vent
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Mangrove Wetlands

• Tropical saltwater ecosystem
• Form in nutrient-rich tidal flats
• Dominant plants are salt-tolerant mangroves
• Florida, Southeast Asia

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Estuary

• Partially enclosed area where saltwater and
  freshwater mix
• Dominated by salt-tolerant plants
• Examples are Chesapeake Bay, San Francisco Bay,
  salt marshes of New England

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Estuarine Food Webs

• Primary producers are phytoplankton and
  salt-tolerant plants
• Much primary production enters detrital food webs
• Detritus feeds bacteria, nematodes, snails,
  crabs, fish

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Intertidal Zones

• Littoral zone is submerged only during highest
  tides of the year
• Midlittoral zone is regularly submerged and
  exposed
• Lower littoral is exposed only during lowest
  tides of the year

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Rocky Intertidal

• Grazing food webs prevail
• Vertical zonation is readily apparent
• Diversity is greatest in lower littoral zone

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Sandy Coastlines

• Vertical zonation is less obvious than along
  rocky shores
• Detrital food webs predominate

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Upwelling

• Upward movement of water along a coast replaces
  surface waters that move away from shore

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ENSO

• El Nino Southern Oscillation
• Climactic event that involves changes in sea
  surface temperature and air circulation patterns
  in the equatorial Pacific Ocean

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• Between ENSOs
• Warm water and heavy rainfall move west across
  the Pacific
• Warm moist air rises in the western Pacific
  causing storms
• Upwelling of cool water along western coasts
• During an ENSO
• Trade winds weaken and warm water flows east
  across the Pacific
• Sea surface temperatures rise
• Upwelling along western coasts ceases
• Heavy rainfall occurs along coasts, droughts
  elsewhere

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Cholera Connection

• Cholera outbreaks correlate with rises in sea
  temperature
• Copepod population increases when phytoplankton
  increase in warming seas

Copepod host of Vibrio cholerae harbors dormant
stage