The
combination of all the organisms in a given area and the abiotic elements which
affect them.
An ecosystem is an open system because it can exchange energy or materials
with other ecosystems.
Earth is a closed system with respect to nutrients and chemicals, but open with respect to
energy.
Two processes:
* one way flow of
energy - Image
sunlight -> producers
-> consumers
* cycling of nutrients
Trophic
Levels Fig.
37.1
Producers
Primary consumers
Secondary consumers
Tertiary consumers
Quaternary consumers
Omnivores
Decomposers
Detrivores
food chain - Image and Fig 37.3
food webs - Image and Fig 37.2
Gross
Primary Production (GPP)
Net Primary
Production (NPP) - Map
Energy
Partitioning within a Link of the Food Chain - Image and Fig. 37.4
Trophic
Efficiency and Ecological Pyramids
Numbers pyramids - Fig
37.6a and Image
Biomass pyramids - Fig
37.6b and Image
Energy pyramids - Fig 37.6c
and Image
How to feed more humans - Image
Biogeochemical
Cycles
Water Cycle - Fig 37.7
evaporation
transpiration
precipitation
runoff
percolation
groundwater, aquifers
Edwards Aquifer
Nutrient cycling
Carbon Cycle - Fig 37.9 and
Movie
Photosynthesis
Respiration
Major reservoirs:
Atmosphere - CO2 gas
Living organisms
Coal, oil, gas
Dissolved CO 2 in water
Carbon-containing rocks - limestone
Nitrogen Cycle - Fig. 37.10
and Movie
and Movie2
Biological nitrogen fixation - reduction of
N2 to NH4 by bacteria
legume/Rhizobium symbiosis in root nodules
cyanobacteria - heterocysts
Return of nitrogen to the atmosphere by bacteria in the soil:
ammonification: amino acids > NH4
nitrification: NH4 > NO2 > NO3
denitrification: NO3 > N2
Phosphorous Cycle - Fig. 37.11
Importance of phosphorous in nucleic acids,
phospholipids, cell membranes
Stored in rock
No gaseous component to cycle
Slowest of all cycles