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Aim: How do abiotic (physical) limiting Aim: How do abiotic (physical) limiting factors affect growth and survival in an factors affect growth and survival in an
ecosystem ?ecosystem ?
HW due ThursHW due Thurs
Read chapter 5 pg. 118-127Read chapter 5 pg. 118-127
Do Making Connections pg.127Do Making Connections pg.127
Ecosystems and Growth
One of the features of an ecosystem is that its growth is limited under normal conditions by competition for resources within the system and by external factors such as environmental changes
• If the presence or absence of a factor limits the growth of the ecosystems elements, it is called a limiting factor .
• There are several abiotic factors that limit ecosystem growth, including temperature, precipitation, sunlight, soil configuration, and soil nutrients.
Observation of ecosystems in very different geographical regions
Identify the maximum and minimum values and describe the overall shape of the graph
Your task…
• What limits the North American Tundra ecosystem? Explain your reason and point out evidence from the graphs that support your answer.
• What limits the South African Grassland ecosystem? Explain your reason and point out evidence from the graphs that support your answer.
• Work in groups – 5 minutes
North American Tundra
South African Wooded Grassland
• A situation that causes the growth of a population to decrease is called a limiting factor. Some limiting factors depend on the size of the population. Other limiting factors affect all populations in similar ways, regardless of the population size.
Section 5-2
Interest Grabber
Go to Section:
What are limiting factors to population growth ?
Different factors can limit population growthHow is the population size affected by these
factors?
Nu m
ber
of Y
east
Cel
l s
Time (hours)
Carrying capacity
Section 5-1
Figure 5-4 Logistic Growth of Yeast Population
Go to Section:
population growth…Logistic
Growth of Aphids
Section 5-2
A Density-Dependent Limiting Factor
Go to Section:
Exponential Growth
• Unlimited resources
• Absence of predation
• No disease
PopulationGrowth
can be
represented bycharacterized by characterized by represented by
which cause a
Exponentialgrowth
Logisticgrowth
Fallinggrowth rate
S-shapedcurve
Limits ongrowth
No limits on growth
J-shapedcurve
Constantgrowth rate
Unlimitedresources
Section 5-1
Concept Map
Go to Section:
60
50
40
30
20
10
01955 1960 1965 1970 1975 1980 1985 1990 1995
2000
1600
1200
800
400
0
2400
Moose Wolves
Section 5-2
Figure 5-7 Wolf and Moose Populations on Isle Royale
Go to Section:
How would you explain what is happening to the moose and wolf population ?
Agriculture begins
Plowingand irrigation
Bubonicplague
IndustrialRevolutionbegins
Section 5-3
Human Population GrowthHuman population growthIs there a Carrying Capacity for Homo
sapiens?