Ecosystem Ecology

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 - Fig 1.7 - Fig 54.1
         sunlight -> producers -> consumers
* cycling of nutrients

Gross Primary Production (GPP)

Net Primary Production (NPP) - Fig 54.4

Limiting factor - Fig 54.6

Secondary production -
Fig 54.10

    Energy Partitioning within a Link of the Food Chain

    Trophic Efficiency and Ecological Pyramids

Energy pyramids - Fig 54.11
Biomass pyramids - Standing Crop Biomass - Fig 54.12
Numbers pyramids - Fig 54.13
How to feed more humans - Fig 54.14

Biogeochemical Cycles

A general model of nutrient cycling - Fig 54.15

Water Cycle - Fig 54.16

groundwater, aquifers
Edwards Aquifer

Carbon Cycle - Fig 54.17
Major reservoirs:

Atmosphere - CO2 gas
Living organisms
Coal, oil, gas
Dissolved CO
2 in water
Carbon-containing rocks - limestone

Nitrogen Cycle - Fig 54.18

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 > NH
nitrification: NH
4 > NO2 > NO3
denitrification: NO
3 > N2

Phosphorous Cycle - Fig 54.19

Importance of phosphorous in nucleic acids, phospholipids, cell membranes
Stored in rock
No gaseous component to cycle
Slowest of all cycles

A review of nutrient cycling - Fig 54.20