1. Chapter 3: The Biosphere
The Study of Ecology

2. What is Ecology?
Ecology is the scientific study of interactions among organisms and between organisms and their environment

3. Why do we study ecology?
We live in the natural world and use its resources (water, space,food, etc)
The natural world effects our lives (weather, fire, economy)
To protect biodiversity

4. Levels of Organization
Ecologists recognize there is a hierarchy of organization in the environment: biosphere, biome ecosystem, community, population, and organisms

5. Levels of Organization

6. What is a Biosphere?
Part of Earth in which life exists including land, water, and air or atmosphere

7. What is a Biome?
Temperate Forest
Tundra
A group of ecosystems that have the same climate and similar dominant communities

8. What is an Ecosystem?
A collection of all organisms that live in a particular place, which includes the nonliving, or physical, environment

9. What is a Community and a Population?
A community is assemblage of different populations that live together in a defined area
A population is a group individuals that belong to the same species and live in the same area

10. How Do We Study Ecology? Observing Experimenting
Modeling (Ecological phenomena that occur over long periods of time)

11. How Do Organisms Obtain Energy in an Ecosystem?
Sunlight is the main energy source for life on Earth
Autotrophs will then use the energy from the sun (or chemicals) to make their own food
Autotrophs are also known as producers
Examples of autotrophs: plants, algae, cyanobacteria

12. How Do Organisms Obtain Energy in an Ecosystem?
Autotrophs use photosynthesis to convert sunlight, carbon dioxide, and water into oxygen and carbohydrates

13. How Do Organisms Obtain Energy in an Ecosystem?
What if there is no light in the ecosystem?
The autotrophs will use chemosynthesis, which is a process that uses chemical energy to produce carbohydrates (ex: bacteria living in volcanic vents)

14. How Do Organisms Obtain Energy in an Ecosystem?
Organisms that rely on other organisms for energy are known as consumers or heterotrophs

15. Types of Heterotrophs Herbivores- consume only plants
Carnivores- consume only meat
Omnivores- consume both plants and animals
Detritivores- consume plant and animal remains (earthworms, mites, crabs)
Decomposer= breaks down organic matter to obtain energy (bacteria & fungi)

16. Feeding Relationships
Energy in an ecosystem flows in one direction (from sun to the heterotrophs)
Food chain- a series of steps in which organisms transfer energy by eating and being eaten

17. Food Chain

18. Food Web

19. Transfer of Energy
Each step in a food chain or food web is called a trophic level
Autotrophs make up the first trophic level, consumers make up 2nd, 3rd, 4th or higher levels
Only about 10% of energy is transferred to organisms at the next trophic level

20. Transfer of Energy
If 10% of solar energy is captured by plants then animals who eat the grass gain only 10% of that energy (1%), animals who those animals gain 10% from that (.1%)
10% --> 1% --> .1%

21. What is Biomass?
Biomass is the total amount of living tissue within a given trophic level
A biomass pyramid can show you much food is available to each trophic level

22. Recycling Matter in the Biosphere
Elements, chemical compounds, and other forms of matter are passed from one organism and from one part of the biosphere to another in biogeochemical cycles

23. Important Biogeochemical Cycles
Water cycle
Carbon Cycle
Nitrogen Cycle
Phosphorus Cycle

24. The Water Cycle

25. The Water Cycle Water moves between the ocean, atmosphere, and land
Water evaporates from bodies of water into the atmosphere
Water can also enter the atmosphere through transpiration (process by which water is lost through the leaves of plants)

26. Nutrient Cycles
A nutrient is a chemical substance that an organism needs to sustain life
Important nutrient cycles
Carbon Cycle
Nitrogen Cycle
Phosphorus Cycle

27. The Carbon Cycle Carbon’s Roles Ingredient in living tissue
Important component of animal skeletons (CaCO3)
Important component of the atmosphere (CO2)

28. The Carbon Cycle Carbon enters the atmosphere by:
Respiration
Geochemical processes
Human activities
Carbon is taken up by:
Photosynthesis
Burial and decomposition of dead organisms (formation of fossil fuels)

29. The Carbon Cycle
CO2 in
Atmosphere
CO2 in Ocean

30. The Nitrogen Cycle The roles of nitrogen:
Important component of amino acids
Major component of fertilizer (NO3-)
Major component of atmosphere (N2)

31. The Nitrogen Cycle
Nitrogen gas (N2) cannot be used by plants so it must be converted into a usable form
Soil bacteria convert nitrogen gas into ammonia (NH3) in the process of nitrogen fixation
More soil bacteria convert ammonia into nitrates (NO3-) and nitrites (NO2-) a usable form
Other soil bacteria then convert nitrates and nitrites back into nitrogen gas, which is known as denitrification

32. The Nitrogen Cycle

33. The Phosphorus Cycle Roles of Phosphorus
Important component of DNA and RNA
Does not enter atmosphere (gas)
Steps
Phosphorus is found in rocks and sediment which gets moved by water
Plants absorb phosphorus in the form of phosphate from soil and water
Heterotrophs consume plants

34. What is a Limiting Nutrient?
A nutrient that is scarce of cycles very slowly
When an aquatic ecosystem receives a large amount of a limiting nutrient it immediately increases the amount of algae, which is known as algal bloom

35. Algal Bloom
What is the result of algal bloom?