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 - 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