Name_____________
Date_______________
Ecology Graphing Packet
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Part 1: Ecology Graphs
Graph 1: Rabbits Over Time
a. The graph shows a __________ growth
curve.
b. The carrying capacity for rabbits is
______
c. During which month were the rabbits in
exponential growth?
Graph 2: Average Toe Length
a. In 1800, about how many people surveyed
had a 3 cm toe? _______
How many in 2000? _______
b. The data shows the ____________
selection has occurred?
c. In 2000, what is the average toe length?
______ What is the average toe length in
1800 _______
Graph 3: Mexico and US
a. In Mexico, what percentage of the
population is between 0-4 years of age?
_______ In the US? ______
b. Which population is growing the fastest?
________
c. Which age group has the smallest number
in both countries? _____
STOP: Have Mr. Carter check your answers before moving on
Chart 4: Trapping Geese
In order to estimate the population of geese in Northern Wisconsin,
ecologists marked 10 geese and then released them back into the
population. Over a 6 year period, geese were trapped and their
numbers recorded.
a. Use the formula to calculate the estimated number of geese in the
area studied? _____________
b. This technique is called ____________ & ______________
c. Supposing more of the geese found in the trap had the mark,
would the estimated number of geese in the area be greater or lesser?
_____
Chart 5: Mushroom Plots
Another ecologist uses a different method to estimate the number of
mushrooms in a forest. She plots a 10x10 area and randomly chooses
5 spots, where she counts the number of mushrooms in the plots and
records them on the grid.
a.Calculate the number of mushrooms in the forest based on the grid
data: _________________
b. Thie technique is called _______________
Year
Geese
Trapped
Number with Mark
1980
10
1
1981
15
1
1982
12
1
1983
8
0
1984
5
2
1985
10
1
Chart 6: Snakes & Mice
Mice
born
Mice
died
1960 2
1000
200
1970 10
800
300
1980 30
400
500
1990 15
600
550
2000 14
620
600
2001 15
640
580
Year
The data shows populations of snake and mice
found in an experimental field.
a. During which year was the mouse population
at zero population growth? ______
b. What is the carrying capacity for snakes ?
______
c. What is the carrying capacity for mice?
_____
d. What is the rate of growth (r) for mice during
1970? _____
Snakes
During 1980? ______
STOP: Have Mr. Carter check your answers when you finish
Part 2) Deer: Predation or Starvation
Introduction: In 1970 the deer population of an island forest reserve about 518 square kilometers in size
was about 2000 animals. Although the island had excellent vegetation for feeding, the food supply
obviously had limits. Thus the forest management personnel feared that overgrazing might lead to mass
starvation. Since the area was too remote for hunters, the wildlife seervice decided to bring in natural
predators to control the deer population. It was hoped that natural predation would keep the deer population
from becoming too large and also increase the deer quality (or health), as predators often eliminate the
weaker members of the herd. In 1971, ten wolves were flown into the island.
The results of this program are shown in the following table. The Population Change is the number of deer
born minus the number of deer that died during that year. Fill out the last column for each year (the first has
been calculated for you).
Year
Wolf
Population
Deer
Population
Deer Offspring
Predation
Starvation
Deer Population
Change
1971
10
2,000
800
400
100
+300
1972
12
2,300
920
480
240
1973
16
2,500
1,000
640
500
1974
22
2,360
944
880
180
1975
28
2,224
996
1,120
26
1976
24
2,094
836
960
2
1977
21
1,968
788
840
0
1978
18
1,916
766
720
0
1979
19
1,952
780
760
0
1980
19
1,972
790
760
0
1. Graph the deer and wolf populations on the graph below. Use one color to show deer populations and
another color to show wolf populations.
STOP: Have Mr. Carter check your graph before moving on
Analysis
1. Describe what happened to the deer and wolf populations between 1971 and 1980.
2. What do you think would have happened to the deer on the island had wolves NOT been introduced?
3. Most biology textbooks describe that predators and prey exist in a balance. This "balance of nature"
hypothesis has been criticized by some scientists because it suggests a relationship between predators and
prey that is good and necessary. Opponents of this hypothesis propose the following questions:
Why is death by predators more natural or "right" then death by starvation?
How does one determine when an ecosystem is in "balance"?
Do predators really kill only the old and sick prey? What evidence is there for this statement?
What is your opinion of the balance of nature hypothesis? Would the deer on the island be better off, worse
off, or about the same without the wolves. Defend your position.
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STOP: Have Mr. Carter check your answers when you finish
Part 3: The Lesson of the Kaibab
Introduction: The environment may be altered by forces within the biotic community, as well as by
relationships between organisms and the physical environment. The carrying capacity of an ecosystem is
the maximum number of organisms that an area can support on a sustained basis. The density of a
population may produce such profound changes in the environment that the environment becomes
unsuitable for the survival of that species. For instance, overgrazing of land may make the land unable to
support the grazing of animals that lived there.
Objectives:



Graph data on the Kaibab deer population of Arizona from 1905 to 1939
Determine factors responsible for the changing populations
Determine the carrying capacity of the Kaibab Plateau
Background
Before 1905, the deer on the Kaibab Plateau were estimated to number about 4000. The average carrying
capacity of the range was then estimated to be about 30,000 deer. On November 28th, 1906, President
Theodore Roosevelt created the Grand Canyon National Game Preserve to protect the "finest deer herd in
America."
Unfortunately, by this time the Kaibab forest area had already been overgrazed by sheep, cattle, and horses.
Most of the tall grasses had been eliminated. The first step to protect the deer was to ban all hunting. In
addition, in 1907, The Forest Service tried to exterminate the predators of the deer. Between 1907 and
1939, 816 mountain lions, 20 wolves, 7388 coyotes and more than 500 bobcats were killed.
Signs that the deer population was out of control began to appear as early as 1920 - the range was
beginning to deteriorate rapidly. The Forest Service reduced the number of livestock grazing permits. By
1923, the deer were reported to be on the verge of starvation and the range conditions were described as
"deplorable."
The Kaibab Deer Investigating Committee recommended that all livestock not owned by local residents be
removed immediately from the range and that the number of deer be cut in half as quickly as possible.
Hunting was reopened, and during the fall of 1924, 675 deer were killed by hunters. However, these deer
represented only one-tenth the number of deer that had been born that spring. Over the next two winters, it
is estimated that 60,000 deer starved to death.
Today, the Arizona Game Commission carefully manages the Kaibab area with regulations geared to
specific local needs. Hunting permits are issued to keep the deer in balance with their range. Predators are
protected to help keep herds in balance with food supplies. Tragic winter losses can be checked by keeping
the number of deer near the carrying capacity of the range.
Data Table
DATA
1. Graph the deer population data.
Year
Deer Population
1905
4,000
1910
9,000
1915
25,000
1920
65,000
1924
100,000
1925
60,000
1926
40,000
1927
37,000
1928
35,000
1929
30,000
1930
25,000
1931
20,000
1935
18,000
1939
10,000
STOP: Have Mr. Carter check your graph before moving on
Analysis
1. During 1906 and 1907, what two methods did the Forest Service use to protect the Kaibab deer?
2. Were these methods successful? Use the data from your graph to support your answer.
3. Why do you suppose the population of deer declined in 1925, although the eliminated of predators
occurred?
4. Why do you think the deer population size in 1900 was 4,000 when it is estimated that the plateau has a
carrying capacity of 30,000?
5. Why did the deer population decline after 1924?
6. Based on these lessons, suggest what YOU would have done in the following years to manage deer
herds.
1915:
1923:
7. It is a criticism of many population ecologists that the pattern of population increase and subsequent
crash of the deer population would have occurred even if the bounty had not been placed on the predators.
Do you agree or disagree with this statement. Explain your reasoning.
8. What future management plans would you suggest for the Kaibab deer herd?
STOP: Have Mr. Carter check your answers when you finish
Part 4: More Graphing
Bacteria
Bacteria reproduce by splitting in half. It takes about 20 minutes, under ideal conditions, for a bacteria
population to double. Fill in the table
below and then graph your data on the
graph paper at right.
Time (min)
0
20
40
60
80
100
120
140
160
180
200
220
240
# of bacteria
1
2
Analysis Questions
1. Describe what is happening to the population of bacteria.
2.
Is the rate of population growth, slowing down, or speeding up? Explain your answer.
3.
This growth is under IDEAL situations (plenty of space, plenty of food, no competition
or predators). How might your graph look different if the bacteria, for example, ran out
of food?
Compare your bacterial growth graph to the human
population growth graph at left.
4.
How are the graphs similar?
5.
What is the trend in human population growth?
6.
Do you think this growth will be able to continue forever? Why or why not
STOP: Have Mr. Carter check your answers before you move on
White Pine
White pine became extinct in northern Minnesota during the last period of glaciation, although it remained
in southern climates such as Virginia. Once the glaciers began to retreat, the white pine began to expand
northward again; it reappeared in northern
Minnesota about 9400 years ago, this is year 0
in the graph.
Time
(years)
0
15
30
45
60
75
90
105
120
135
150
# of white
pine trees
20
23
31
57
92
156
163
98
106
108
107
STOP: Have Mr. Carter check your graph before you move on
Analysis Questions
1. What happens to the population growth after 90 years?
2.
What happens to the population growth after 120 years?
3.
What is the approximate carrying capacity (maximum number of trees it can safely
contain) of white pine in this ecosystem?
4.
What factors would affect the carrying capacity of white pines?
5.
What caused the pine population to grow so much between 0 and 90 years?
STOP: Have Mr. Carter check your answers before you move on
Lynxes and Hares
Lynxes are a small cat native to North America and Asia that preys mainly on the snowshoe hare.
1.
What happens to the lynx population right after the Hare population peaks?
2.
What happens to the Hare population right after the Lynx population peaks?
3.
What happens to the Hare population when the Lynx population hits bottom?
4.
What happens to the Lynx population as the hare population increases?
5.
What would happen to the Hare population if the Lynxes were removed from the ecosystem
(in both the short term and the long term?
6.
How might the presence of Lynxes be good for the hares?
Ecological Studies of Wolves and Moose on Isle Royale
Isle Royale is the largest island located in Lake Superior. The island is approximately 45 miles in
length and 9 miles wide. Isle Royale consists of Isle Royale (main island) and multiple smaller islands. Isle
Royale is about 12 miles south of Canada, 20 miles Southeast of Grand Portage, Minnesota and 53 miles
north of Copper Harbor, Michigan. Isle Royale National Park was established in 1940, designated a
wilderness area in 1976 and an International Biosphere Reserve in 1980. Isle Royale is a remote island, the
only mode of transportation available is by boat or seaplane.
Moose first arrived at Isle Royale around 1900. The moose population tends to increase in years
with mild winters, early spring green-up, abundant winter forage, low wolf numbers and low levels of tick
infestation. Wolves first arrived at the island on an ice bridge from Canada in 1940. Disease has also
influenced the wolf population. Between 1980 and 1982, the wolf population declined from 50 to 14, due to
canine parvovirus.
The Isle Royale wolves and moose have been studied since 1959. This Isle Royale wolf-moose
study is unique because it entails just a single predator (the wolf) and a single prey (the moose) on a small
island with very little human influence. This is the longest continuous study of a predator and its prey.
Predator/Prey on Isle Royale
Analysis Questions
1. What is the greatest moose population? What year did that occur?
2.
What was the wolf population when the moose population the greatest?
3.
What would happen to the moose population if the wolf population decreases?
4.
What would happen to the wolf population if the moose population decreases?
5.
What would happen to the moose population if the wolves were removed from Isle
Royale?
6.
Describe the pattern between the wolf population in relation to the moose population.
7.
Identify a factor, other than moose population, that may influence the wolf population in
Isle Royale.
8.
Identify two factors, other than the wolf population, that may influence the moose
population.
9. Isle Royale has been undeclared as a national park and has been purchased by a large resort
conglomerate. Describe some possible positive and negative changes and how they
impact on the Isle Royale ecosystem.
STOP: Have Mr. Carter check your answers when you finish