1. Ecosystems & The Flow of Energy & Matter
PACKET #80
CHAPTERS #54 & #50

2. Introduction Ecosystem
Encompasses all the interactions among organisms living together in a particular place, and among those organisms and their abiotic environments
Individual communities and their abiotic environments
Earth, which encompasses the biosphere (all of Earth’s communities) and its interaction with Earth’s water, soil, rock and atmosphere, is the largest ecosystem
Abiotic factors
Biotic factors
What are the differences between abiotic and biotic factors?
What is the relationship between abiotic and biotic factors?

3. Ecosystems
ENERGY FLOW

4. Energy Flow Through Ecosystems
The flow of energy is linear—as energy cannot be reused by organisms
Energy begins as solar energy, which is trapped by photosynthesis in the form of chemical energy
Chemical energy is then available to do work

5. Energy Flow II Energy flow describes who eats whom in ecosystems
A food chain describes the sequential passage of energy
A food web shows the complexity of interconnected food chains
Remember that a food web is composed of many food chains

6. Energy Flow III Food Chain Refresher
Primary producers are autotrophs and comprise the first trophic level
Herbivores, primary consumers, comprise the second trophic level
May find omnivores here
Carnivores and/or omnivores, comprise trophics level three and higher all the way to the decomposers

7. Energy Flow IV Ecological Pyramid Illustrates the trophic levels
May be a pyramid of
Numbers

8. Energy Flow V Ecological Pyramid Illustrates the trophic levels
May be a pyramid of
Biomass

9. Energy Flow VI Ecological Pyramid Illustrates the trophic levels
May be a pyramid of
Energy

10. Ecosystems
PRODUCTIVITY

11. Productivity I Energy flow begins with primary productivity
The amount of light energy converted to chemical energy, in the form of organic molecules, by an ecosystem’s autotrophs, over a given period of time.
Gross Primary Productivity (kilocalories fixed per area per time OR grams carbon fixed)
Expresses the total rate of photosynthesis of an ecosystem
Net Primary Productivity (kilocalories fixed per area per time OR grams carbon fixed)
The energy remaining after cellular respiration
Gross total productivity – energy used for cellular respiration

12. Productivity II
Primary Productivity is always expressed as a RATE and is represented via
Kilocalories fixed per area per time
Joules per square meter per year
Grams carbon fixed (Biomass)
The dry weight of vegetation added to an ecosystem per unit area per unit time
Grams per square meter per year

13. Productivity III
Rates of productivity are influenced by environmental factors
Tropical rain forests are the most productive terrestrial ecosystems
Wetlands, coral reefs, and estuaries are the most productive aquatic ecosystems

14. Productivity IV
Energy flow is never 100% efficient and results in the Pyramid of Productivity

15. Productivity V
Relationship of productivity to biological diversity is complex
Ecosystems may be more diverse as productivity increases, but after a certain point, diversity will decline with increasing productivity
Important when considering nutrient-enriched environments
Especially those that are impacted by human application of fertilizers and enrichment by animal wastes.

16. Cycles of Matter in Ecosystem

17. Introduction
Biochemical cycles are cycles of matter between the abiotic and biotic components of the environment
Carbon, nitrogen, phosphorus and water cycles are central to life on earth
Carbon, nitrogen and water cycles have atmospheric components and cycle on a global scale

18. Carbon Cycle
Carbon dioxide is the pivotal molecule in the carbon cycle
Human activities, since the beginning of the Industrial Revolution, have contributed an increasing amount of carbon dioxide to the atmosphere by burning fossil fuels

19. Nitrogen Cycle Bacteria are essential to this cycle
Nitrogen fixing bacteria converts nitrogen gas to ammonia
Nitrifying bacteria converts ammonia to nitrate
Denitrifying bacteria converts, anaerobes, convert nitrate to nitrogen gas
Nitrogen is needed for the production of proteins
Nitrogen oxides are also an ingredient in photochemical smog

20. Phosphorus Cycle
Fertilizers, runoff containing animal wastes, and sewage introduce phosphorus into aquatic ecosystems
Phosphorus loss accelerated by clear cutting
Brazil

21. Water Cycle
Enough said!

22. Abiotic Factors in Ecosystems
THE SUN

23. The Sun Warms the earth Solar energy biogeochemical cycles
Temperature changes with latitude
Sun’s rays strike the equatorial regions vertically which result in warmer temperatures

24. The Sun II Temperature changes with season
Tilting of the Earth’s axis causes the amount of solar radiation to vary during the year
How does this help with the establishment of ocean currents?
How does temperature change help with support life in standing bodies of water?
More to come

25. Review