1. An Ecological System: The Biogeochemical Cycles
The water cycle
The Carbon Cycle
The Nitrogen Cycle
The Phosphorus Cycle
The cycling of nutrients through the biosphere for use throughout the system by food chains, webs, and the biosphere.
The nutrients: carbon, hydrogen, oxygen, Nitrogen, and Phosphorus

2. Biosphere:5 miles up and 5 miles down

3. The Water Cycle: Hydrogen and Oxygen
Continuously moves throughout the atmosphere, the land, and waters (oceans, lakes and rivers)
Water vapor condenses in the air and falls as precipitation then gets back into the air during evaporation
Evaporation from plants is called Transpiration

5. The Water Cycle
transpiration

6. The Carbon and oxygen Cycles: Carbon and Oxygen
The continuous movement of carbon and oxygen from non-living into living organisms
CO2 in atmosphere build organic molecules
Plants use CO2 to produce O2
This exchange of CO2 for O2 is called Respiration (cellular respiration)
Combustion or burning releases carbon
Burning trees, fossil fuels: oil and coal

7. The Carbon Cycle

8. Nitrogen Cycle: Nitrogen (N)
Nitrogen Is needed to make proteins (DNA, RNA, Enzymes)
Is a process where nitrogen circulates among the air, soil, water, and organisms
Nitrogen Fixation: where bacteria that live in soil or on roots, or lightening change chemical composition of N2 into ammonia – a useable form of nitrogen by living organisms

9. Nitrogen Cycle:
Nitrification: The changing of un-useable nitrogen, nitrite, into useable Nitrate
De-nitrification: Changes nitrate into nitrogen gas that returns to atmosphere

10. Biological Nitrogen Fixers
Cyanobacteria – blue-green algae
Free living soil bacteria
Mycorrhizae:
Symbiotic bacteria living in root nodules
Chemical Fixators: Lightening
There are two general types of nitrogen fixers
Cyanobacteria – primary producers, e.g., blue/green algae – fix their own carbohydrates
Bacteria that require a source of carbohydrates
Get it from dead organic matter in soil
Get it directly from plants in a symbiotic relationship - mychorhizae

11. Root nodules on Cassia fasciculata

12. Nitrogen is available in three soluble forms in soils
·      Nitrification is a series of processes associated with decomposition, fixation and transformation of N in the soils
Nitrates are the form of nitrogen used by plants
But nitrogen also exists in soil solutions as ammonia, and nitrite
Nitrogen compounds are extremely volatile, breaking down very quickly

13. The Nitrogen Cycle

14. Phosphorus Cycle: Phosphorus
An important ingredient in DNA and RNA and all proteins
Flows in organism in different chemical forms into the surroundings and back into organisms
Doesn’t enter atmosphere
In soil and rock. Dissolves and is used by plants
Plants are eaten by animals, animals die, cycle begins again

15. Phosphorous Cycle Phosphate – PO4-3
Phosphorous is an extremely important nutrient as well that is limiting to plant growth
·       There is lots of phosphorous in mineral form
Getting it in phosphate, the form taken up by plants, is the big issue in terms of nutrient cycling
Microbes again mobilize Phosphorous, i.e. put it in a form that can be used by plants

16. The Phosphorus Cycle

17. Cycles compared to Energy Flow
Cycles are recycled through the biospere by food webs, the hydrosphere, the biosphere, the geosphere, atmosphere
Energy flows through food webs, is made by plants initially from the sun
Is used by living organisms, passed on, and is lost into space

19. Do you see the energy flow and cycles?

20. Ecological
Succession

21. Ecological Succession
The orderly, natural changes and species replacements that take place in the communities of an ecosystem.
Over time biotic and abiotic factors create ecological conditions that are suitable for some organisms and unsuitable for others.
Changing the ecosystem along the way.

22. Primary Succession
Succession beginning in an area or surface on which there has never been life before
Exposed
rock
Lichen
& mosses
Grasses,
herbs,
scrubs,
larger scrubs,
tree seedlings
Aspen, jack
Spruce, pines
White spruce,
Balsam fur,
Paper birch
climax community
pioneer
species
TIME

23. Secondary Succession
Occurs in a region in which life has existed before, but the previous community structure has been disrupted
climax community
Frequently seen in North Georgia where cultivated fields like old cotton or soybean fields are abandoned

24. Secondary Succession
What could cause the previous ecological community to have been disrupted?
FIRE
FLOOD
LANDSLIDE

25. Climax Community

26. Biomes
A large region characterized by a specific type of climate and certain types of plants and animals