Lecture Ecology

1
Lecture Ecology

• Chapter 54 Ecosystems and the Biosphere
• Chapter 55 Ecology and the Geography of Life

2
Relationships, I

• Trophic structure / levels feeding relationships
  in an ecosystem
• Primary producers the trophic level that
  supports all others autotrophs
• Primary consumers herbivores
• Secondary and tertiary consumers carnivores
• Detrivores/detritus special consumers that
  derive nutrition from non-living organic matter
• Food chain trophic level food pathway

3
Relationships, II

• Food webs interconnected feeding relationship in
  an ecosystem

4
Energy Flow, I

• Primary productivity (amount of light energy
  converted to chemical energy by
  autotrophs) Gross (GPP) total energy
  
  Net (NPP) represents
  the storage of energy available to consumers
  Rs respiration
• NPP GPP - Rs
• Biomass primary productivity reflected as dry
  weight of organic material
• Secondary productivity the rate at which an
  ecosystem's consumers convert chemical energy of
  the food they eat into their own new biomass

5
Energy Flow, II

• Ecological efficiency of E transferred from
  one trophic level to the next (5-20)
• Pyramid of productivity multiplicative loss of
  energy in trophic levels
• Biomass pyramid trophic representation of
  biomass in ecosystems
• Pyramid of numbers trophic representation of the
  number of organisms in an ecosystem

6
Chemical Cycling

• Biogeochemical cycles the various nutrient
  circuits, which involve both abiotic and biotic
  components of an ecosystem
• Water Water moves among ocean, land and
  atmosphere in the hydrologic cycle
• Carbon Carbon dioxide is the pivotal molecule
  in this cycle
• Nitrogen Bacteria are essential to this cycle
• Phosphorus This cycle lacks a gaseous component

7
Human Impact

• Biological magnification trophic process in
  which retained substances become more
  concentrated at higher levels
• Greenhouse effect warming of planet due to
  atmospheric accumulation of carbon dioxide and
  other gases
• Ozone depletion effect of chlorofluorocarbons
  (CFCs) released into the atmosphere
• Rainforest destruction
• Cause Overpopulation?

8
Abiotic factors

• Biospherethe sum of all the planets ecosystems
• Biome areas of predominant flora and fauna
• Temperature
• Water
• Sunlight
• Wind
• Rocks Soil
• Periodic disturbances

Ecotone biome grading areas
9
Global climate

• Seasons

Precipitation Winds
10
Aquatic biomes

• Vertical stratification
• photic zone photosynthetic light
• aphotic zone little light
  thermocline narrow stratum of rapid
  temperature change
• benthic zone bottom substrate
• Organisms
• Phytoplankton community of small free-floating
  producers
• Zooplankton community of small free-floating
  consumers
• Nekton community of larger free-floating
  consumers
• Benthos community of bottom-dwelling organisms
• Detritus dead organic matter food for benthic
  organisms

11
Freshwater biomes

• Littoral zone shallow, well-lit waters close to
  shore
• Limnetic zone well-lit, open water farther from
  shore
• Profundal zone deep, aphotic waters
• Lake classification oligotrophic deep,
  nutrient poor eutrophic shallow, high nutrient
  content mesotrophic moderate productivity
• Wetland area covered with water
• Estuary area where freshwater merges with ocean

12
Lake stratification turnover

• Thermal stratification vertical temperature
  layering
• Biannual mixing spring and summer
• Turnover changing water temperature profiles
  brings oxygenated water from the surface to the
  bottom and nutrient rich water form the bottom to
  the surface

13
Marine biomes

• Intertidal zone area where land meets water
• Neritic zone shallow regions over continental
  shelves
• Oceanic zone very deep water past the
  continental shelves
• Pelagic zone open water of any depth
• Benthic zone seafloor bottom
• Abyssal zone benthic region in deep oceans

14
Terrestrial biomes

• Tropical forests equator most complex constant
  temperature and rainfall canopy dry and wet
• Savanna tropical grassland with scattered trees
  occasional fire and drought large herbivores
• Desert sparse rainfall (arid) (lt30cm/yr)
• Chaparral spiny evergreens at midlatitudes along
  coasts
• Temperate grassland all grasses seasonal
  drought, occasional fires large mammals
• Temperate deciduous forest midlatitude regions
  broad-leaf deciduous trees
• Coniferous forest cone-bearing trees
• Tundra permafrost very little precipitation