1. Ecosystems: Concepts and Fundamentals Chapter 6

2. 6.1 The Ecosystem: Sustaining Life on Earth Ecosystem: a ecological community of living and non-living attributes. It is the minimum system that includes and sustains life.

3. 6.1 The Ecosystem: Sustaining Life on Earth Ecosystems have two major parts: living and nonliving Ecological community: the living part of the ecosystem

4. 6.1 The Ecosystem: Sustaining Life on Earth Two major functions in an ecosystem: Cycling of chemical elements Flow of energy Ecosystems include some sort of fluid medium (air, water, both) We will learn about cycling of chemical elements in the next chapter.

5. 6.1 The Ecosystem: Sustaining Life on Earth Cycle: wastes are converted into food, which is converted into wastes, which must be converted once again into food, etc. For this to take place, many species have to interact with each other The simplest ecosystem has one species that produces its own food and another that decomposes the waste of the first species and a fluid medium

6. 6.2: Ecological Communities and Food Chains Food chains: The linkage of who feeds on whom Food webs: more complex linkages Trophic level: all organisms in a food web that are the same number of feeding levels away from the original energy source

7. 6.2: Ecological Communities and Food Chains Photosynthesis: process of using sunlight to create food Autotrophs: an organism that produces its own food Heterotrophs: Organism that cannot make its own food so it lives by feeding on another

8. 6.2: Ecological Communities and Food Chains Herbivores: an organism that feeds on an autotroph Carnivores: Eat heterotrophs Omnivores: Eat both autotrophs and other heterotrophs

9. 6.2: Ecological Communities and Food Chains Ex: Yellowstone National Park (Wyoming) – geyser basins Photosynthetic bacteria and algae make up the spring’s first trophic level.

10. 6.2: Ecological Communities and Food Chains Ephydrid flies (herbivore) make up the second trophic level Dolichopodid fly: feeds on the eggs and larvae of the ephydrid flies (carnivore)

11. 6.2: Ecological Communities and Food Chains Ex: Yellowstone National Park (Wyoming) – geyser basins The herbivorous ephydrid flies have parasites, so they would be on the third trophic level Decomposers would be the fourth trophic level, because they feed on all of the dead wastes

12. 6.2: Ecological Communities and Food Chains Ex: Yellowstone National Park (Wyoming) – geyser basins The community is dependent on 1.Sunlight 2.Constant flow of hot water Without these, they cannot survive.

13. 6.2: Ecological Communities and Food Chains Case Study: Sea Otters Keystone species: if this species declines, the whole ecosystem falls apart.

14. 6.2: Ecological Communities and Food Chains Food webs in the oceans generally involve more species. Pelagic ecosystem (open ocean ecosystem) In the hot springs example, the food webs and trophic levels were neat. In reality, this is not true Ex: harp seal (see figure)

15. 6.2: Ecological Communities and Food Chains

16. 6.3 Ecosystems as Systems Ecosystems are open systems: energy and matter flow into and out of them Where does an ecosystem start and where does it end? Commonly used way of determining where a boundary of an ecosystem on land is is the watershed. All rain that reaches the ground from any source and flows out into one stream.

17. 6.4 Biological Production and Ecosystem Energy Flow Ecosystem energy flow: movement of energy through an ecosystem from the external environment The issue is that energy is a difficult and abstract concept. It is invisible to us and especially hard to measure with ecosystems

18. 6.4 Biological Production and Ecosystem Energy Flow What limits the amount of organic matter in living things? Entropy: there is a decrease in order, and energy is disorganized

19. 6.5 Biological Production and Biomass Biomass: total amount of organic matter in any ecosystem Biological production: capture of usable energy from the environment to produce organic matter Gross production: the increase in stored energy before any is used Net production: the amount of newly acquired energy stored after some energy has been used.

20. 6.5 Biological Production and Biomass Primary production: production carried out by autotrophs Secondary production: the production carried out by heterotrophs Chemoautotrophs: organisms that create energy from chemicals

21. 6.6 Energy Efficiency and Transfer Efficiency No system can be 100% efficient. Energy efficiency: ratio of output to input, and is usually further defined as the amount of useful work obtained from some amount of available energy

22. 6.7 Ecological Stability and Succession Ecosystems change and recover and overcome these changes Ecological succession: the process of ecosystems recovering

23. 6.7 Ecological Stability and Succession

29. 6.8 Chemical Cycling and Succession

37. 6.9 How Species Change Succession