Trophic Categories Etc..

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  • Topic: Soil, Nitrogen, Nitrogen fixation
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Trophic Categories:

1. Producers
2. Consumers
3. Detritus feeders and decomposers

Producers = organisms that capture energy from the sun or from chemical reactions to convert carbon dioxide to organic matter

Organic Matter vs. Inorganic Matter
-Matter that makes up the bodies of living things generally characterized by the presence of carbon and hydrogen bonds.

Most producers are green plants.

i.Chemosynthetic bacteria
ii.Green plants
iii.Protists (some)

Primary consumers = {herbivores} {omnivores}
secondary consumers, tertiary consumers etc. = {carnivores}

Predator Prey Relationships:

Predator: organism which does the feeding
Prey: organism that is fed on


Parasites: organisms intimately associated with their "prey" feeding on it over time, typically without killing it. Host

Detritus: dead plant material, fecal wastes of animals, dead animal bodies etc. Detritivores: earthworm, millipedes, fiddler crabs, termites, ants, wood beetles. Primary detritus feeders, secondary detritus feeders??

Decomposers: fungi and bacteria (cause rotting of dead trees, branches and leaves)
Secrete digestive enzymes (special group of detritivores)
Secondary detritus feeders: protozoans, mites, insects and worms feed on decomposers.

Trophic Levels
4thtertiary consumers (Carnivores)
3rdsecondary consumers (Carnivores + Omnivores)
2ndprimary consumers (Herbivores)
1stproducers (Chemosynthesizers, photosynthesizers)

Non-Feeding Relationships:
Mutually supportive relationships
Mutualism: mutual benefit between species. E.g. flowers and pollinating insects.
Some organisms cannot live alone: lichens (fungus [protection] and alga [food]) Symbiosis: "living together" (harmful or beneficial; parasitic or mutualistic)

Even predator-prey relationships, mutual advantages exist. Killing of individual prey that are weak or diseased may benefit the population as a whole by keeping it healthy. Predators and parasites may also prevent herbivore populations from becoming so abundant that they overgraze their environment (which might jeopardize the entire ecosystem). --what about humans? Hitler. Genocide. Disease. War. Over-Development.

Are all species in a giant "free-for-all?"
No. fierce competition rarely exists as each species tends to be specialized and adapted to its own habitat or niche.

Abiotic Factors

Environments contain interplay of physical & chemical factors (abiotic factors) •Two types: Conditions and Resources
•Conditions: vary in space & time but cannot be depleted
•e.g. temperature, wind, pH, salinity, turbidity & fire
•Resources: factors consumed by organisms
•e.g. water, chemical nutrients, light & oxygen [objects of competition

The degree to which each abiotic factor is present profoundly affects the ability of organisms to survive. Each species may be affected differently.The differences in response to abiotic environmental factors determine which species survive or decline in a given environment. These organisms, in turn, determine the nature of the ecosystem

Four Spheres
Three open systems occupied by biosphere:
Lithosphere: earth's crust, minerals & rocks
Hydrosphere: water in liquid and solid compartments
& atmosphere: thin layer of gases (inclu. Water vapor) separating earth from space

Key Elements:
Carbon, Hydrogen, Oxygen, Nitrogen, Phosphorus and Sulphur
=make up tissues of biota
where are the six key elements found in the environment? Look to the spheres. Atmosphere
3 important gases: O2, N2, CO2 + water vapor
75.523% nitrogen, 23.133% oxygen, 1.288% argon, 0.053% carbon dioxide, 0.001267% neon, 0.00029% methane, 0.00033% krypton, 0.000724% helium 0.0000038 % hydrogen  Relatively rare. why? 75% of normal matter. light weight escapes...
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