1. How Ecosystems Work

2. The Sun Life depends on the sun
The sun is the ultimate source of energy for almost all organisms
Photosynthesis – a series of chemical reactions that use light to convert water and carbon dioxide into sugar and oxygen
6CO2 + 6H2O → C6H12O6 + 6O2
Plants, algae and some bacteria do photosynthesis

3. Producers & Consumers Producers – organisms that make their own food
Autotrophs – self-feeders
Get their energy directly from the sun
Consumers – organisms that get their energy by eating other organisms
Heterotrophs – other-feeders
Get their energy indirectly from the sun by eating producers or other consumers

4. Producers & Consumers

5. The Exception to the Rule
Deep-ocean ecosystems thrive where there is no sunlight
Producers make food from hydrogen sulfide from the hot ocean vents instead of sunlight
Other organisms then eat these producers

6. Types of Consumers
Herbivores – consumers that eat only producers (plant-eaters)
Carnivores – consumers that eat only other consumers (meat-eaters)
Omnivores – consumers that eat both plants and animals (eaters of all)
Decomposers – consumers that break down dead organisms

7. What Eats What Name Energy Source Examples Producer Makes its own food
Grasses, ferns, algae, bacteria
Consumer
Gets energy by eating other organisms
Mice, starfish, humans, ants
Herbivore
Eats only producers
Cows, sheep, deer, grasshoppers
Carnivore
Eats only other consumers
Lions, hawks, spiders
Omnivore
Eats both producers and consumers
Bears, pigs, humans
Decomposer
Breaks down dead organisms
Fungi, bacteria

8. Respiration
Cellular respiration - gets the energy out of the food by using oxygen to break it down
All living things use cellular respiration to get energy from food
C6H12O6 + 6O2 → 6CO2 + 6H2O
Essentially the reverse of photosynthesis

9. Food Chains
Each time an organism eats another organism, energy is transferred
Food chain – a sequence in which energy is transferred from one organism to the next as each organism eats another

10. Food Webs
Ecosystems are much more complicated than a simple food chain
Food web – shows many feeding relationships in an ecosystem

11. Trophic Levels
Trophic level – each step in the transfer of energy through an ecosystem
Each time energy is transferred, less of it is available to organisms at the next level
Some energy is lost during the process of respiration; most is used for daily functions
About 90% of the energy is used; only 10% is left for the next trophic level

12. Trophic Levels

13. Water Cycle Water moves between the Earth’s surface and the atmosphere
The sun provides the energy to drive the cycle
Evaporation – water changes from a liquid to a gas
Precipitation – water vapor cools and falls to Earth as rain, sleet, or snow
Groundwater – layer of water underground

14. Water Cycle Living organisms move water about…
Carried within bodies (by drinking it or extracting it from food)
During respiration, water is excreted
Water also evaporates from the skin as sweat
Plant roots collect water from the soil
Some is used for photosynthesis
Some is evaporated or transpired from the leaves

15. Water Cycle What are the 3 phases of water? Solid Liquid Gas
Ex. Glaciers, ice on the surface of a lake or pond
Liquid
Ex. oceans, rivers, streams, lakes
Gas
Ex. Water vapor
Water vapor cannot be seen, but we know that fog and clouds contain it

16. Water Cycle

17. Carbon Cycle
Carbon is an essential part of proteins, fats, and carbohydrates needed for life
Producers take CO2 from the atmosphere
Consumers eat the producers to obtain carbon
CO2 is released back to the atmosphere during cellular respiration
Fossil fuels store carbon that is then released when they are burned

18. Carbon Cycle Four main reservoirs of carbon: Atmosphere
Carbon dioxide, carbon monoxide
Terrestrial Biosphere
Includes freshwater, soil
Oceans
Dissolved carbon, living organisms in the ocean
Sediments
Fossil fuels

19. Carbon Cycle Four processes involved in the carbon cycle:
Biological processes – photosynthesis, respiration & decomposition
Geochemical processes – release of carbon dioxide gas into the atmosphere by volcanoes
Mixed biogeochemical processes – burial of carbon-rich organisms and their conversion to fossil fuels
Human activity – mining, burning of fossil fuels

20. Carbon Cycle

21. Nitrogen Cycle All organisms need nitrogen to build proteins
Nitrogen gas makes up 78% of the atmosphere
Nitrogen-fixing bacteria – Convert nitrogen from the air into ammonia (nitrogen fixation)

22. Nitrogen Cycle
Ammonia is converted into nitrates and nitrites, which plants and other producers can use (nitrification)
Bacteria convert nitrogen in the soil into atmospheric nitrogen (denitrification)
Decomposers return nitrogen to the soil

23. Nitrogen Cycle

24. Phosphorus Cycle
Phosphorus is an element that is part of many molecules that make up the cells of living organisms.
Plants get the phosphorus they need from soil and water, while animals get their phosphorus by eating plants or other animals that have eaten plants.
The phosphorus cycle is the cyclic movement of phosphorus in different chemical forms from the environment to organisms and then back to the environment.

25. Phosphorus Cycle Continued
Phosphorus may enter soil and water when rocks erode. Small amounts of phosphorus dissolve as phosphate, which moves into the soil.
Plants absorb phosphates in the soil through their roots.
Some phosphorus washes off the land and ends up in the ocean.
Because many phosphate salts are not soluble in water, they sink to the bottom and accumulate as sediment.

27. Fertilizers and the Nitrogen and Phosphorus Cycles
Fertilizers contain both nitrogen and phosphorus.
Excessive amounts of fertilizer can enter terrestrial and aquatic ecosystems through runoff.
Excess nitrogen and phosphorus can cause rapid growth of algae.
Excess algae can deplete an aquatic ecosystem of important nutrients such as oxygen, on which fish and other aquatic organisms depend.

29. Acid Precipitation
When fuel is burned, large amounts of nitric oxide is release into the atmosphere.
In the air, nitric oxide can combine with oxygen and water vapor to form nitric acid.
Dissolved in rain or snow, the nitric acid falls as acid precipitation.

30. Acid rain damage on gargoyle
Trees killed by acid rain

31. Sulfur Cycle
Sulfur is one of the components that make up proteins and vitamins.
Proteins consist of amino acids that contain sulfur atoms.
Sulfur is important for the functioning of proteins and enzymes in plants, and in animals that depend upon plants for sulfur.
Plants absorb sulfur when it is dissolved in water. Animals consume these plants, so that they take up enough sulfur to maintain their health.

32. Sulfur Cycle Continued
Most of the earth's sulfur is tied up in rocks and salts or buried deep in the ocean in oceanic sediments.
Sulfur can also be found in the atmosphere. It enters the atmosphere through both natural and human sources.
Natural recourses: volcanic eruptions, bacterial processes, evaporation from water, or decaying organisms.
When sulfur enters the atmosphere through human activity, this is mainly a consequence of industrial processes where sulfur dioxide (SO2) and hydrogen sulphide (H2S) gases are emitted on a wide scale.

33. Sulfur Cycle Continued
When sulfur dioxide enters the atmosphere it will react with oxygen to produce sulfur trioxide gas (SO3), or with other chemicals in the atmosphere, to produce sulfur salts.
Sulfur dioxide may also react with water to produce sulphuric acid (H2SO4). Sulphuric acid may also be produced from demethylsulphide, which is emitted to the atmosphere by plankton species.
All these particles will settle back onto earth, or react with rain and fall back onto earth as acid depostion.

35. Rock Cycle Group of changes
Igneous rock can change into sedimentary rock or into metamorphic rock
Sedimentary rock can change into metamorphic rock or into igneous rock
Metamorphic rock can change into igneous or sedimentary rock

36. Igneous Rock Igneous rock forms when magma cools and makes crystals.
Magma is a hot liquid made of melted minerals. The minerals can form crystals when they cool.
Igneous rock can form underground, where the magma cools slowly. Or, igneous rock can form above ground, where the magma cools quickly.

37. Sedimentary Rock
On Earth's surface, wind and water can break rock into pieces.
The rock pieces, called sediments, drop from the wind or water to make a layer.
After a long time the sediments can be cemented together to make sedimentary rock. In this way, igneous rock can become sedimentary rock.

38. Metamorphic Rock
Baked rock does not melt, but it does change. It forms crystals.
Because this rock changes, it is called metamorphic.
Metamorphosis can occur in rock when they are heated to 300 to 700 degrees Celsius.

40. Succession
A regular pattern of changes over time in the types of species in a community
May take hundreds or thousands of years
Climax community – the community that eventually forms if the land is left undisturbed
Two types of succession
Primary succession
Secondary succession

41. Primary Succession
Occurs on surfaces where no ecosystem existed before
New islands created by volcanic eruptions
Land exposed when a glacier retreats
No soil exists
It takes several hundred to several thousand years to produce soil naturally
Pioneer species – first organisms to populate an area (usually lichens)
Lichens → mosses → grasses → shrubs → trees

42. Primary Succession

43. Secondary Succession
Occurs on a surface where an ecosystem has previously existed
Volcanic eruption, forest fire, abandoned farmland
Occurs much more quickly than primary succession because there is already fertile soil