Lecture Notes Packet

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BS102 Environmental Biology

• Lecture Notes Packet 3
• Daniel W. Ward

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Land Biomes

• Connections between Climate and Vegetation
• Climate
• the average long term (30 years) weather of an
  area.
• it determines the type of vegetation of that
  area.
• factors which determine climate
• temperature
• precipitation
• Biome
• a region of the world with a characteristic type
  of natural, undisturbed plant community.

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Land Biomes

• Three Major Types of Land Biomes
• Deserts / Semideserts
• Grasslands
• Forests

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Land Biomes

• Deserts / Semideserts
• General Characteristics
• plants exhibit a slow rate of growth.
• there is low species diversity.
• there are periodic water shortages.
• they take a long time to recover from any type of
  disruption.

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Land Biomes

• Tropical Deserts
• compose 1/5 of the worlds desert areas.
• they are one of the most dry areas on the planet.
• few plants can survive there.
• characterized by hard, windblown surfaces strewn
  with rocks and some sand.
• examples are the Sahara and Namib deserts.

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Land Biomes

• Temperate Deserts
• exhibit some seasonal temperature differences.
• during the summer, the daytime temperatures are
  hot.
• during the winter, the daytime temperatures are
  cool.
• an example would be the Mojave desert.
• Cold Desert
• exhibit definite seasonal temperature
  differences.
• summers are hot.
• winters are cold.
• an example would be the Gobi desert.

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Land Biomes

• Semideserts
• have a long dry season followed by a short, heavy
  rainy season.
• dominated by thorn trees and shrubs.
• located between true deserts and grasslands.

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Land Biomes

• Grasslands
• Tropical Grasslands
• exhibit high average temperatures.
• have low to moderate average precipitation.
• they are located in a wide belt on each side of
  the equator beyond tropical rain forests.
• they contain huge herds of grazing and browsing
  hoofed animals.
• they often have fires in the dry season.
• an example would be the savannas of Africa.

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Land Biomes

• Temperate Grasslands
• cover vast areas of the interiors of the major
  continents.
• exhibit bitterly cold winters and hot, dry
  summers.
• suffer from occasional fires.
• experience frequent droughts.
• Types
• Tall Grass Prairie - Midwest, western US and
  Canada.
• Short Grass Prairie - Midwest, western US and
  Canada.
• Pampas - South America.
• Veld - Africa.
• Steppe - central Europe and Asia.

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Land Biomes

• Polar Grasslands / Arctic Tundra
• bitterly cold and windy most of the year.
• covered with snow and ice much of the year.
• experience long, dark winter and short, long
  daylight summers.
• covered with a thick, spongy mat of low growing
  plants.
• located south of the polar ice cap (northern
  hemisphere).
• low decomposition rate, shallow soil, slow growth
  rates make it very easy to disrupt.

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Land Biomes

• Permafrost
• thick layer of ice beneath the soils surface
  that remains frozen all year round.
• prevents the establishment of trees.
• the upper layer thaws during the summer but the
  moisture cant seep into the ground.

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Land Biomes

• Tropical Rain Forest
• this is a type of evergreen broadleaf forest.
• it is located near the equator.
• it covers only 2 of the Earths surface.
• characterized by warm annual mean temperatures,
  with little seasonal or daily variation.
• also is characterized by high humidity and almost
  daily heavy rainfall.
• contains the greatest number of species per unit
  of area of any biome.
• soil nutrients are a limiting factor, not water
  and temperature.

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Land Biomes

• Tropical Deciduous Forest
• located between tropical rain forests and
  tropical savannas.
• characterized by being warm all year round.
• experiences alternating wet (monsoon) and dry
  seasons.
• composed of a mixture of drought resistant
  tropical evergreens and deciduous trees (loose
  their leaves during the dry season).
• Tropical Scrub Forest
• similar to tropical deciduous forest, except it
  occurs where the dry season is longer.
• mainly composed of small deciduous trees and
  shrubs.

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Land Biomes

• Temperate Deciduous Forest
• experiences moderate average temperatures.
• characterized by 4 distinct seasons with long
  summers and mild short winters.
• precipitation is abundant and spread over the
  entire year.
• plants life is dominated by a few species which
  survive the winters by dropping their leaves and
  becoming dormant.

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Land Biomes

• Evergreen Coniferous / Boreal Forest / Taiga
• located just south of the arctic tundra.
• experience a sub-arctic climate
• long, cold, dry winters with 6-8 hours of light
  per day.
• short, mild summers with 19 hours of light.
• dominated by a few species of conifers (fairly
  low plant diversity).
• fallen needles cover the nutrient poor forest
  floor making the soil acidic and preventing the
  growth of most other plants.
• during the summer the forest floor retains water
  and forms bogs.

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Water Environments

• water covers over 70 of the Earths surface.
• it plays a major role in regulating the Earths
  climate.
• Types of Water Environments
• Ocean / Marine
• Freshwater Lakes
• Freshwater Streams
• Inland Wetlands

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Water Environments

• Ocean Zones
• Coastal Zone
• usually warm water rich in nutrients.
• includes the shallow water extending from the
  high tide mark on the land to the edge of the
  continental shelf.
• composes less then 10 of all oceans areas.
• contains 90 of all marine species and it is the
  site of the major commercial fisheries.
• has a high primary productivity per unit area.
• most densely populated and intensely used of the
  ocean zones.

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Water Environments

• Examples
• Coral Reefs
• located in tropical and subtropical oceans.
• composed of coral, algae, and other producers.
• they provide habitats for many marine species.
• protect 15 of all coastlines from erosion.
• they grow very slowly and can be disrupted
  easily.
• Estuaries
• where fresh water and salt water mix (usually
  near the mouths of rivers).

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Water Environments

• Coastal Wetlands
• land which is covered all or part of the the year
  with salt water.
• these areas provide breeding areas and habitat
  for a variety of wildlife.
• these are being lost rapidly.
• Beaches
• Rocky Shores - rocks and tidal pools
• Barrier Beaches - gentle slope to the ocean, sand
  dunes, they are prime development sites.
• Barrier Islands
• parallel running, long, thin, offshore islands.
• protect mainland, estuaries, lagoons, and
  wetlands.

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Water Environments

• Open Ocean
• contains 10 of all marine species.
• characterized by low primary productivity per
  unit area.
• Subdivided based on light penetration.
• Vertical Zones
• Eupohtic Zone
• photosynthetic zone, high light penetration.
• Bathyl Zone
• twilight zone, moderate light penetration.
• Abyssal Zone
• darkness zone, little or no light penetration.

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Water Environments

• Freshwater Lakes
• large natural bodies of standing fresh water.
• formed when rainfall, runoff, flowing groundwater
  fills depressions in the Earth.
• these depressions are formed by
• placation.
• crystal displacement.
• volcanic activity.

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Water Environments

• Types of Freshwater Lakes (based on nutrients)
• Eutrophic Lake
• have a large supply of nutrients.
• Oligotrophic Lake
• small supply of nutrients.
• Mesotrophic Lake
• moderate supply of nutrients.

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Water Environments

• Lake Zones
• Littoral Zone
• the edge of the lake.
• most submerged vegetation occurs here.
• Limnetic Zone
• upper zone of the lake.
• considerable light penetration.
• Profundal Zone
• the lower zone of the lake.
• moderate light penetration.
• Benthic Zone
• the bottom of the lake (mud).

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Water Environments

• Thermal Stratification (deep lakes)
• thermal stratification occurs due to the fact
  that water is densest as a liquid (4 degrees
  centigrade) rather than a solid (0 degrees
  centigrade).
• Epilimnion
• the upper layer of warm water and high levels of
  dissolved oxygen.
• Hypolimnion
• the lower layer of cold, denser water with low
  levels of dissolved oxygen.

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Water Environments

• Thermocline
• the middle layer where temperature change rapidly
  with depth increases.
• acts as a barrier to the transfer of nutrients
  and dissolved oxygen between the upper and lower
  layers.

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Water Environments

• Turnover
• Fall Turnover
• result of the cooling atmosphere.
• the epilimnion sinks to the bottom when it cools
  to around 4o C.
• the thermocline disappears.
• this brings nutrients from the bottom sediments
  to the top.
• also brings dissolved O2 from the top to the
  bottom.
• Spring Turnover
• due to the warming atmosphere.
• warms the epilimnion to 4o C, and it sinks to the
  bottom.
• the result is the same as fall turnover.

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Water Environments

• Freshwater Streams
• flowing bodies of surface water.
• Watershed / Drainage Basin
• the land area that delivers water, sediment, and
  dissolved substances by small streams, to large
  streams, and eventually to the ocean.

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Water Environments

• River System Zones
• Headwater / Source Zone
• composed of cold, clear water.
• turbulent flow results in large amounts of O2
  being dissolved from the air.
• Transition Zone
• the merging of headwater streams to form wider,
  deeper streams.
• flow is down gentle slopes with fewer obstacles.

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Water Environments

• Flood Plain Zone
• transition zone streams merge to form wide, deep
  rivers.
• meander across broad, flat valleys.
• main channels support a variety of species.
• backwaters have species similar to lakes.

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Water Environments

• Inland Wetlands
• covered by freshwater at least part of the year.
• located away from coastal areas.
• includes
• bogs, marshes, prairie potholes, swamps, mud
  flats, flood plains, wet meadows. wet tundra.
• provide habitats for wildlife.
• improve the water quality by filtering, diluting,
  and degrading sediments and pollutants as water
  flows through them.

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Water Environments

• regulate stream flow by storing water during
  periods of heavy rainfall - releases it slowly
  thus reducing erosion and damage.
• recharges the groundwater supplies.