1. Ecosystems
Chapter 17

2. Section 17-1
What is an ecosystem?

3. Organisms Interact with Each Other
Ecology is the study of the interactions of living organisms with one another and their environment
A habitat is the place where a population lives
A community is the many different species that live together in a habitat

4. Organisms Interact with Each Other
An ecosystem consists of a community and all the physical aspects of its habitat like soil, water and weather
The physical aspects of the habitat are abiotic factors (non-living)
The living organisms in a habitat are biotic factors

6. Ecosystems support diverse communities
The number of species living within an ecosystem is a measure of its biodiversity

7. Ecosystem inhabitants
Includes all of the large animals, small animals, trees, soil, water, insects and so on

8. Ecosystems Change over time
The first organisms to live in a new habitat are small fast growing plants called pioneer species

9. Succession
A somewhat regular progression of species replacement is succession
Primary succession occurs where plants have not grown before
Secondary succession occurs in areas where there has been previous growth

12. Energy flow in ecosystems
Section 17-2
Energy flow in ecosystems

13. Primary Energy Source
Most life on earth depends on photosynthetic organisms
Why?
They capture sunlight and store it as chemical energy!

14. Primary Energy Source cont…
Primary productivity is the rate at which organic material is produced by photosynthetic organisms
Primary productivity determines the amount of energy available in an ecosystem

15. Primary Energy Source cont…
Producers, like plants, are organisms that first capture energy (sunlight)
Consumers are organisms that consume organisms to obtain energy

16. Trophic Levels
Ecologists study how energy moves through an ecosystem by assigning organisms to a specific level or trophic level
The level is determined by the organisms source of energy

17. Trophic Levels cont…
The path of energy through the trophic levels of an ecosystem is called a food chain

18. Trophic Levels cont… Producers are the lowest level
Herbivores are on the second level and called primary consumers
Secondary consumers are carnivores and omnivores
Tertiary consumers are carnivores that eat other carnivores

19. Trophic Levels
Detrivores are organisms that get energy from organic waste
Bacteria and fungi are called decomposers because they cause decay

20. Food Web
In ecosystems, energy does not follow a straight path because man animals feed at different trophic levels
This causes an interconnected group of food chains called a food web

22. Energy Transfer Energy is lost within the ecosystem as heat
It is not a useful source of energy in ecosystems
As we move up the trophic levels, the energy store by the organism is 1/10th of the energy stored by the previous level

23. Pyramid of Energy
An energy pyramid is a diagram in which each trophic level is represented by a block, stacked one on top of the other

24. Ecosystems cycle materials
Section 17-3
Ecosystems cycle materials

25. Materials Cycle between Living and Non-Living Things
Water, carbon, nitrogen and phosphorus pass from the nonliving environment to living organisms and back to nonliving environment
That cycle is called a biogeochemical cycle

26. Water Cycle is Driven by the Sun
Water has the greatest influence on an ecosystem
Water vapor condenses, rains, seeps into the Earth and becomes ground water
Water is heated by the sun, evaporates and reenters the atmosphere

28. The Carbon Cycle is Linked to Energy
Respiration: Organisms use oxygen and produce CO2
Combustion: Carbon returns to the air through combustion or burning
Erosion: Marine organisms use CO2 to make shells. Shells become sediment and as the sediments erode, carbon is made available

30. Plants and Bacteria use Nitrogen and Phosphorus
Nitrogen and phosphorus build proteins and nucleic acids
Phosphorus is part of ATP
The atmosphere is 79% Nitrogen
Nitrogen fixing bacteria (combine H and N to form ammonia) live in the soil

31. Nitrogen Cycle
Assimilation or absorption of nitrogen into plant and animal compounds
Ammonification is the production of ammonia by bacteria during decay
Nitrification is the production of nitrate from ammonia
Denitrification is the conversion of nitrate to Nitrogen gas

33. Sustainable Agriculture
The growth of plants is limited by the availability of nitrogen in the soil
Decomposers return mineral nutrients to the soil, however crops are harvested and nutrients were lost
Sustainable Ag is farming that remains productive, profitable and replenishes the soils nutrients, reduces erosion and controls weeds and pests

34. Sustainable Agriculture
Farmers will plant cover crops after harvest to keep the soil from eroding away, store water and provide nutrients to bacteria and insects after being plowed under
Farmers will rotate their cattle and sheep in several pastures to prevent overgrazing