1. ECOLOGY
Part 2 - Chapter 3.4 Cycles

2. How energy flows . . . Sun - main source of energy
Autotrophs / producers… can make own food
Heterotrophs / consumers… must eat
Decomposers / saprophytes… fungi & bacteria break down dead materials

3. Biogeochemical Cycles Within Ecosystems: Chapter 2.3, pg. 45 - 49
Water cycle – precipitation, evaporation and condensation
Carbon cycle – increasing carbon dioxide traps more heat and causes the “greenhouse effect.”
Phosphorus cycle – cycles between organisms and the land.
Nitrogen cycle – converts atmospheric nitrogen (N2) to a form useable by organisms.

4. Water Cycle Processes:
Evaporation – liquid changes to a gas (Transpiration – occurs from plants)
Condensation – gas changes to a liquid (clouds form)
Precipitation – temperature dependent a. re-evaporates b. surface runoff – rivers, streams, ocean c. stored as ground water - collection

5. Water Cycle

6. Carbon/Oxygen Cycle
The basis of this is the reciprocal process of photosynthesis and respiration.

8. Carbon/Oxygen Cycle
Cell respiration by animals and bacterial decomposers adds carbon dioxide to the air and removes oxygen.

10. Carbon/Oxygen Cycle
The burning of fossil fuels adds carbon dioxide to the air.
Photosynthesis removes carbon dioxide from the air and adds oxygen.

12. Nitrogen cycle
Very little nitrogen enters the ecosystems directly from the air.
Most of it enters an ecosystem by way of bacterial processes.

13. Nitrogen Cycle

14. Nitrogen cycle Nitrogen fixation is the conversion of…
“N2” into usable organic compounds by bacteria
“N2” from decaying organisms into ammonia

15. Nitrogen Cycle

16. Nitrogen Cycle
N2 fixing bacteria live in the roots of legumes and convert free N2 into the ammonium ion (NH4+).

17. Nitrogen Cycle
Nitrifying bacteria converts the ammonium ion (NH4+) into nitrites (NO2-): 2NH4+ +3O2  2NO2- + 4H+ + energy and then into Nitrates: 2NO2- + O2  2NO3- + energy

18. Nitrogen Cycle

19. Nitrogen Cycle Denitrifying bacteria convert nitrates (NO3-)
into free atmospheric nitrogen (N2)
“N2” is released from organisms that are
being decomposed.

20. Phosphorus Cycle
Phosphorus is essential to living organisms because it forms a part of vital molecules such as DNA and RNA.
It’s not abundant in the biosphere.
Phosphorus in the form of inorganic phosphate remains mostly on land (rocks, soil minerals, oceans, sediments)

21. Phosphorus Cycle
Phosphate is gradually released during weathering, cycling between organisms and the soil.
Plants bind phosphate into organic compounds and cycles through the food web from producers to consumers.

23. Phosphorus Cycle
Some phosphate washes into rivers and streams and dissolves ending up in the oceans.
Marine organisms process and incorporate it into biological compounds.
Phosphorus is taken up by primary producers, reused by consumers, and released by excretion and decomposing matter.

25. Nutrient Limitations How does nutrient availability relate to the primary productivity of an ecosystems?
Ample sunlight & water availability are basic requirements
Availability of nutrients may be a limiting factor
Limiting nutrient – single essential nutrient that limits productivity in an ecosystem

26. Nutrient Limitations in Soil
Fertilizers supply missing nutrients
Usually contain large amounts of nitrogen, phosphorus, & potassium
Micronutrients – calcium, magnesium, sulfur, iron & manganese needed in smaller amounts

27. Nutrient Limitation in Aquatic Ecosystems
Compared to land the ocean is nutrient-poor
Nitrogen is often the limiting nutrient in oceans
Phosphorus in streams, lakes and freshwater environments
Runoff – algae blooms disrupt ecosystems

28. The End! .
Go and Recycle!