1. Bio NOTES: Succession and Population Ecology
Succession - a series of predictable changes that occurs
in a community over time
Two types:
1. primary succession
2. secondary succession
Terms:
pioneer species – the first organisms that live in a previously
uninhabited area
climax community – a stable, mature community that undergoes
little or no change
limiting factors – environmental factors that affect an organism’s
ability to survive (food, predators, space)
Each biome on Earth has a different type of climax community
- grasslands - rainforest

2. Primary Succession Secondary Succession occurs when a disturbance
of some kind changes an
existing community without
removing the soil
occurs on surfaces where
no soil exists
the colonization of new sites
by communities of organisms
called pioneer species
takes less time than primary
succession because soil is
already present
disturbances include wildfires,
storms, deforestation, farming
rocks
 lichens
 mosses 
 grasses, shrubs
 trees
soil
 grasses, shrubs
 trees

3. All living organisms are limited by factors in the environment
Population Ecology

4. CHAPTER 3.1 & 4.1
POPULATION ECOLOGY
In Chapter 2, you learned that organisms depend on one another for survival. You also learned about abiotic factors and that abiotic factors affect individual organisms. How, then, might these factors affect communities and populations?

5. CHAPTER 2
REVIEW TERMS
Population is a group of individuals of the same type (or species)
Species is a group of organisms that can interbreed and produce fertile offspring

6. Population growth = an increase in the size of a
population over time
 Birth rate greater than death rate  population grows
 Birth rate equals death rate  population stays the same
 Death rate greater than birthrate  population shrinks

7. Factors that change population size:
1.immigration – movement of individuals into a population from
another population
2. births – causes an increase in population size
3. emigration – movement of individuals out of a population and
into another population
4. deaths – causes a decrease in population size

8. BIRTH
DEATH
IMMIGRATION
EMIGRATION

9. Exponential growth = as a population gets larger, it grows faster
Under ideal conditions with unlimited resources, a population will grow exponentially.
Exponential growth = as a population gets larger, it grows faster
“J” curve
Humans are currently experiencing exponential growth. But we know this is not always the case.

10. EXPONENTIAL GROWTH CURVE
Population growth is NOT limited
Takes on an J-shape
Ideal and doesn’t normally occur in most populations
What kinds of organisms might have exponential growth and why?

11. Two types of Limiting Factors:
Limiting factor = Any biotic or abiotic factor that restricts the numbers of organisms
Examples: food, water, shelter, etc
Two types of Limiting Factors:
density-dependent
density-independent

12. Density-dependent limiting factors
- affected by the number of individuals in a given area
competition and availability of food, water and space
predation
parasitism and disease
DEPENDS on the # of individuals

13. Density-independent limiting factors
- limit a population’s growth regardless of the density
of the population
unusual weather
natural disasters
human activities (pollution or dam building)

14. CARRYING CAPACITY
The maximum number of individuals that can be supported by the ecosystem.
The limit is determined by the availability of resources and by their interactions with other organisms.

15. LOGISTIC GROWTH CURVE:
Occurs when population growth is limited by factors in the environment
As resources become less
available, the growth of the
population slows or stops.
Take on the “S” curve
carrying
capacity
Reaches carrying capacity
All organism eventually reach this

16. J-CURVE VS. S - CURVE
All populations will eventually display an S-curve.

17. Human Population Growth!

18. REPRODUCTIVE PATTERNS
Species of organisms vary in the number of births per reproductive cycle, in the age that reproduction begins, and in the life span of the organism.
R-strategist
K-strategist

19. R-strategist Small organism (fruit fly or a mouse) Short life span
Produce many offspring
Strategy is to produce as many offspring as possible in a short time in order to take advantage of some environmental factors
Populations are controlled by density-independent factors (changes in abiotic factors)

20. K-strategist (also called Carrying Capacity Strategy)
Large organism (elephant)
Long life span
Produce fewer offspring but invest a lot of care
Strategy is to produce only a few offspring who have a better chance of living due the care they get from parents
Populations are controlled by density-dependent (biotic factors)

21. Which are you?
R-strategist
K-strategist

22. Human Impacts on the Environment
How do humans affect the populations of species?
Human Impacts on the Environment

23. Humans have played a large role in the loss of Biodiversity on the planet.
Biodiversity = the variety of life in an area

24. Worldwide, about half of the area covered by forests has been cleared.
Bio NOTES: Human Impact on the Environment
1. Effects of Human Overpopulation:
loss of land/habitat
water and food shortage
poor sanitation
species extinction
poverty
emerging disease
2. Deforestation – loss of forests
- cause soil erosion, loss of habitat, and species extinction
Worldwide, about half of the area covered by forests has been cleared.
3. Threats to biodiversity – the variety of organisms is decreasing
- an imbalance can cause extinction
4. Pesticide use – using chemicals to kill and control pests
- will sometimes kill non-target species
- pollutes water sources
- causes health problems
5. Biological magnification
– concentrations of a harmful substance increase
in organisms at higher trophic levels in a food web

25. Effects on Air Quality Global Warming Acid Rain The earth’s atmosphere
keeps some heat from
going out into space
Rain that has been made acidic
by certain pollutants in the air.
Pollution in our atmosphere
causes too much heat to
stay on earth
Changes overall temperature/
climate
Raises sea level
Affects health of ecosystems
pollutants = sulfur dioxide
and nitrogen oxides from
burning fossil fuels
causes health problems
damages forests and lakes
damages buildings
Harmful to animals

26. The Greenhouse Effect:

27. Effects on Water Quality
The runoff of silt, soil, pesticides, and fertilizers from agricultural
land is the largest single source of water pollution.
Eutrophication:
- excess fertilizers can run off into lakes and ponds
- this stimulates plant and algae overgrowth
- a buildup of algae can lower the levels of dissolved oxygen in
the water
- this leads to the dying off of the fish population
- over time, lakes and ponds slowly begin to fill in
Why can’t you just clean up
polluted water?
- it is expensive
- who pays for it?
- technology not available for all types

28. Effects on Natural Resources
Renewable resources
- can regenerate if they are living or can be replenished
by biochemical cycles if they are nonliving
- ex. trees, fresh water
Nonrenewable resources
- cannot be replenished by natural processes
- ex. fossil fuels
Sustainability = a way of using natural resources without
depleting them for future generations
use renewable resources that can be “restocked”
recycle and reuse products
plant tree farms
only cut down selected trees instead of clear-cutting
follow emission standards 28

29. The Story of Easter Island
Humans first landed on Easter Island between 400 and 700 A.D.
Island had thick forests, rich soil, many bird and animal species
Human population grew quickly over next 1000 years
They cut down forests for lumber and boats faster than the trees
could grow back
Eventually, there were no trees left….no wood for shelter or boats,
rich soil washed away, habitat lost for animal species, no fishing
without boats
With no food, and island resources nearly gone, the Easter Island
human population crashed and the Easter Islanders disappeared.