Aim: How do abiotic (physical) limiting factors affect growth and survival in an ecosystem ? HW due...

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?