1. Ecology
Ch. 3 – The Biosphere

2. 3.1 - What is Ecology?
It is the scientific study of interaction among organisms and between organisms and their environment

3. What is the Biosphere?
The biosphere is the combined portions of the entire planet where life exists.

4. Levels of Organization
To understand relationships within the biosphere ecologists ask questions about events and organisms that range in complexity from a single individual to the entire biosphere

5. Levels (con’t.)
Species: a group of organisms so similar to one another that they can breed and produce fertile offspring.
Populations: a group of individuals that belong to the same species and live in the same area.
Communities: different populations that live together in a defined area.

6. Levels (con’t.)
Ecosystems: all the organisms that live in a particular place, together with their nonliving or physical environment.
Biomes: a group of ecosystems that have the same climate and dominant communities.

7. Levels of Organization

8. Biotic and Abiotic Factors
Biotic Factors – Any living part of the environment with which an organism might interact
Ex. – animals, plants, mushrooms & bacteria
Abiotic Factors – Any nonliving part of the environment
Ex. – sunlight, heat, water, soil, etc.

9. Biotic and Abiotic Factors Together
The differences between biotic and abiotic factors are not always clear and simple
Many physical factors can be strongly influenced by the activities of organisms
Ex. – pond “muck” is a combination of soil (abiotic) and leaf mold & decomposing plant material (biotic)

10. Biotic and Abiotic Factors

11. Ecological Methods
Scientists use three basic approaches to conduct ecological research. They are:
Observing
Experimenting
Modeling

12. 3-2 Energy, Producers, and Consumers
What happens if your car runs out of gas?
What do you need before you can play in a soccer game or run for 5 miles?
Living systems need a constant input of Energy.

13. Primary Producers Autotrophs
Organisms that use energy from the environment to make complex organic compounds
Also known as producers. Why?
Two types
Photosynthesis - Energy from the Sun
Chemosynthesis - Life without Light

14. Primary Producers Primary Producers
The first producers of energy-rich compounds that are later used by other organisms
Energy from the Sun
Capturing light energy and using it to convert CO2 & H2O into O2 & Carbohydrates
Energy without Light
Using chemical energy to make Carbohydrates

15. Sources of Energy

16. Consumers Heterotrophs
Rely on other organisms for their energy and food supply.
Also known as consumers
Why?

17. Consumers Types of Consumers Herbivores Carnivores – Omnivores
Obtain energy and nutrients by eating plant materials
Carnivores –
Kill and eat other animals
Omnivores
Eat both plants and animals
Scavengers
Consume the carcasses of dead animals
Detritivores
Feed on dead and decaying plant and animal remains
Decomposers
Chemically break down matter

18. Beyond Consumer Categories
These simple categories often don’t express the real complexities of nature.
Examples:
Hyenas (carnivores) will scavenge if they get a chance
Aquatic animals will eat a mixture of algae, bits of animal carcasses, and detritus

19. 3.3 Energy Flow in Ecosystems
Energy flows through the ecosystem in one direction.

20. Energy Flow in Ecosystems

21. Food Chain
A series of steps in which organisms transfer energy by eating and being eaten.

22. Food Web
A network of many feeding interactions

23. Food Web

24. Food Webs and Disturbance
Relationships in Food Webs are not simple.
Disturbances do happen and their effects can be dramatic.
Example - Marine Food Web / Krill

25. Antarctic Food Web

26. Trophic Levels and Ecological Pyramids
Each level in a food chain or food web is a trophic level.
Each trophic level depends on the level below it for energy.

27. What is a Trophic Level?

28. Ecological Pyramids
Can be used to represent energy, matter or number of individuals at each trophic level

29. Energy Pyramid
Only 10% of the energy available at one trophic level makes it to the next level
When one organism eats another, energy is lost. Where does this energy go?

30. Energy Pyramid

31. Biomass Pyramid
Represents all the living tissue (food) at each trophic level.

32. Biomass Pyramid

33. Pyramid of Numbers
The number of individual organisms at each trophic level usually decreases as you go up the pyramid of numbers.

34. Pyramid of Numbers

35. 3-4 Cycles of Matter
Unlike the one-way flow of energy, matter is recycled in the biosphere.
Where does your body get the materials, such as Carbon, it needs to function? __________
Elements , chemical compounds and other forms of matter are passed from one organism to another through biogeochemical cycles.
Bio - ______ Geo - ______ Chemical - ______

36. Water Cycle

37. Other Biogeochemical Cycles
Carbon Cycle - carbon is especially important because it is the key ingredient in all living organisms.
Carbon is found in oceans, the air, and certain types of rock.

38. Carbon Cycle

39. Nitrogen Cycle - All organisms require nitrogen to make amino acids which are used to build proteins.

40. Nitrogen Cycle

41. Phosphorus Cycle - Unlike carbon nitrogen and oxygen, phosphorous does not enter the air, it remains mostly in rock, soil minerals, and ocean sediments.
Phosphorous is of great biological importance for molecules like DNA and RNA.

42. Phosphorous Cycle

43. Nutrient Limitation
Primary Productivity: the rate at which organic matter is created by a producer.
Controlled by the availability of nutrients
in the environment
How can a nutrient be a limiting factor for an ecosystem?
If even a single essential nutrient is in short supply, primary productivity will be limited

44. Nutrient Limitation Limiting Nutrient
the nutrient whose supply limits productivity
Ex. - If ample sunlight and water are available, the primary productivity of an ecosystem may be limited by the availability of nutrients.

45. Nutrient Limitation In Soil In Aquatic Ecosystems
Growth of crop plants is limited by one or more nutrients that must be taken up by plants through their roots
That’s why farmers use fertilizers!
In Aquatic Ecosystems
Sometimes receive large amounts of a limiting nutrient (runoff from fertilized fields)
The result can be an Algal Bloom which can cover the water’s surface and disrupt the ecosystem