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Lecture 6

Lecture 6

Earth Sciences
Course Code
Christine Burton

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Glg205 t 6
- On earth there are numerous different life forms. This abundamce of different life forms is
called biodiversity
- Single celled organisms that have a cell wall but the nucleus of the cell is not bound by a
- Protoctista
o Unicellular organization
- fungi
o Live on decaying organic matter
Ecosystem including the organism (biosphere) and its environment (lithosphere, atmostphere,
- Ecosystems have to have energy and nutrient sources (e.g. sun, other organism)
- Producers autotrophs
- Heterotrophs: organisms that need to consumer complex organic compounds to grow their
tissues and for energy
- Decomposers
o Essential in the decomposition of dead organisms
- The feeding level occupied by an organism in a food chain represents its trophic level
- 6 elements form about 95% of plant matter: C, H, O, N, S, P
Ecological pyramids
- Each trophic level is smaller because 10% of energy is lost at each trophic level
- The majority of life is restricted to a zone between 200m below the surface of the oceans to
6000m above sea level
- The ecosphere can be divided into terrestrial and aquatic biomes
Aquatic biomes
- Benthic t live on the bottom
- 6 major mass extinctions just in the phanerozoic
- Most of the carbon is stored on land
o But even more is in the atmosphere
- The open ocean is not very productive but it has a large area
o More productivitiy in the upwelling areas but it has a smaller area
- 30% of oceanic biomass is in estuaries
o 35% in coral reefs/algal beds
- Very low productivity in deserts
o 43% of terrestrial biomass stored in rainforest
Evolution of forest
- *timescale of evolution + major extinction
- Geologists want to know about forest because of oil and carbon cycle
Long-term changes in forests
- Pollen record in lake sediments t palynology
- Open forest have 30% cover vs. closed forest that have 70% cover
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