1. Populations Ecosystems Succession Humans and the Environment
Ecology
Populations
Ecosystems
Succession
Humans and the Environment
Notes & Key: Ecology
Teacher Notes

2. Population Population size
Refers to the number of individuals in a population
Factors that influence this size
Abiotic – nonliving, such as temperature, moisture, air, salinity, and pH
Biotic – all the living organisms that inhabit the environment

3. Population density
Refers to the number of individuals found within a given area
If too wide spread, they rarely encounter each other – difficult to reproduce

4. Dispersion
Refers to the way in which the individuals of the population are arranged
Even – individuals are located at equal intervals
Clumped – bunched together in clusters
Random – location of each individual is determined by chance

5. Population Growth – population grows when more individuals are born than die
Carrying capacity – when a population has reached the maximum size that the environment can support
Size is determined by limiting factors
Food, water, shelter

7. Populations living areas
Habitat = the area in which an organism lives
Niche = the role the organism has in an ecosystem

8. Population relationships
Symbiosis – close association between two different types of organisms – a scientific ‘living together’
Mutualism – both organisms benefit (lichen)
Commensalism – one organism benefits and the other is neither harmed nor helped (epiphytes)
Parasitism – one organism benefits and the other is harmed (flea)

9. Ecosystems Energy Flow
Producers - make their own food (green plants, algae, some bacteria)
Consumers - obtain their food from others
Herbivores – primary consumers that eat plants
Carnivores – secondary consumers that eat flesh
Omnivores – secondary or tertiary consumers that eat plants and flesh
Decomposers – eat dead and decaying organisms

10. Food Chain
Trophic levels
Clover
Rabbit
Snake
Hawk

11. Food Web
Food chains that interconnect
and overlap

12. Pyramid of biomass Pyramid of numbers Pyramid of energy
Total mass of organisms at each trophic level
Pyramid of numbers
Number of organisms at each trophic level
Pyramid of energy
Amount of energy at each trophic level
Each trophic level receives ~ 10% from the next higher level

13. Cycles Water cycle Nonliving Living
Condensation, precipitation, evaporation
Living
Absorption, transpiration

14. Carbon cycle
Atmospheric carbon
Photosynthesis
Cellular respiration

15. Nitrogen cycle Atmospheric nitrogen Nitrogen-fixing bacteria Nitrates
Nitrites
Plants
Animals
Decomposers

16. Oxygen cycle Oxygen in air and water Cellular respiration Water
Photosynthesis

17. Succession Populations in an area are replaced by other populations
Organisms make the environment less conducive for their existence and more conducive for the next level

18. Primary succession – where life did not exist before
Pioneer species
Continuing species change
Climax community
Ex. lichen, grasses, small bushes, small trees, mature softwoods (pines, balsams, firs), mature hardwoods (oaks, hickories)

19. Secondary succession – where a prior community was destroyed (by fire, flood, volcanic eruption, abandoned farming, mining, logging, etc.)
Pioneer species
Continuing species change
Climax community

20. Humans and the Environment
Conservation – Wise management of the Earth’s natural resources
Renewable resources
Nonrenewable resources

21. Renewable resources Wildlife Many threatened or endangered
Extinction occurs when a species disappears from Earth
Habitat destruction is major cause

22. Forests
Becoming smaller due to increased demand for wood and wood products
Deforestation occurs where large areas of forest are cut and cleared. Ex. tropical rainforests
Cut and burned to clear land for farming
Topsoil is thin, good for one, or maybe two, years
Then more must be cleared
When land is cleared, rain ceases as trees caused the rain through transpiration
Land becomes a desert
Reforestation is a solution

23. Soil – good soil is needed to grow plants for food and for fibers to make cloth
Erosion can be prevented
Windbreaks
Contour plowing
Terrace plowing
Strip cropping
Crop rotation

24. Nonrewable resources Water Most important Cannot live without it
Watersheds
Desalination

25. Fossil Fuels
Coal, natural gas, oil
Alternative energy forms
solar energy
nuclear energy
wind power
geothermal energy
water energy

26. Pollution Air pollution Most comes from burning fossil fuels
Smog – smoke and fog
Acid rain – oxides from burning fossil fuel combine with moisture in air
Temperature inversion
Layer of warm air becomes trapped between layers of cool air
Air pollutants become trapped in cool air
Do not rise form the earth, stay near ground

27. Water pollution Agricultural runoff Industrial waste products
One major example is hot water
Causes thermal pollution
Hot water holds less oxygen than cold water