The Bioshphere and Geochemical cycles
- global circulation systems
- The rock cycle
- the leaf system
- the ocean system
“one thing seems to be foreign on this large celestial body consisting of spheres, namely organic life. But this life is limited to a determined zone at the surface of the lithosphere... ...on the surface of continents it is possible to single out an independent biosphere” (Suess, 1875, p. 3)
Modern defintion: the totality of life on earth [Bradbury, 1991]
What is life, and how should it be recognized?
Physicists POV- life= Negative entropy= Entropy creates dispersed energy whereas life can decrease it internal entropy.
Biochemist’s POV- life= Able to use free energy (food or sunlight) to grow according to its genetic instructions.
Darwinian POV- life= Organic molecular entities that can grow and reproduce
Levels of organisation: Macromonlecule- Cell- Tissue- Organ + organ systems- Organism- Population- Communities +ecosystems- Biosphere
seperated into 4 parts:
- inputs= solar energy
- ouputs= heat energy
The Atmosphere, Geosphere and Biosphere interact to generate The Earth System – A coupling of all processes on Earth
in simple words- the idea that the atomsphere, biosphere and geoshere are part of an intgrated system. Changes in any sysem will impact on other parts of the system.
Photosynthetic (and chemosynthetic) organisms synthesize from CO2 the organic building blocks on which all life depends, and so are termed primary producers. Primary productivity refers to the rate at which organic matter is produced.
Gross primary productivity: total amount of carbon, or energy, fixed before respiration.
Primary productivity affected by availability of environmental resources: -Light -Water -Nutrients
And environmental conditions: -Temperature
Net primary productivity : how much vegetation take in during photosynthesis - how much c02 is releasd during repiration. gpm2/day
Positive values indicate more carbon dioxide being absorbed than released. ▫ Negative values indicate release of carbon back into the atmosphere.
Red clay zones:
- Near dead water deader than any terrestrial desert.
- The only sediment which accumumuates is red dust blown from the continents.
- c.1cm of sediment every 1 thousand years.
In general, aquatic primary productivity is lower than terrestrial primary productivity (although pp can be high in estuarine and coastal areas, but low at high altitude / high latitude and desert areas).
- Large proportion of forest biomass is dead and much of the living tissue is not photosynthetic.
- In grassland, more of the biomass is living and involved in photosynthesis.
- In aquatic communities, particularly when dominated by phytoplankton production, dead cells do not accumulate and photosynthetic output is high.
If a hypothetical planet was inhabited by only a single species, it would convert its resources into both copies of itself and waste products (the death of the organisms would also add to the waste product pool).
> Such an ecological system could never work as the organism would run out of crucial resources, as they would be locked up in waste products.