Mastering Ecology Chapters 18 and 19

Order the labels in the flowchart to complete the model of secondary succession as observed in a deciduous forest of eastern North America.

1. Land that was once used for farming is abandoned 2. Nearby grasses and herbs colonize the site 3. Shrubs and fast-growing trees take root 4. Pine forest comes to dominate the site 5. Hardwood trees outgrow the pines

What does the left y-axis of the graph represent?

number of bird species
stage of ecological succession
number of breeding pairs per 100 acres
ecological age

number of breeding pairs per 100 acres

What does the blue graph line represent?

breeding pairs per 100 acres
number of species
ecological age
species density

number of species

After 20 years, what was the total number of bird species?

14
60
120
cannot be determined from this graph

14

In which year was the density of birds greatest?

20
100
105
160
cannot be determined from this graph

105

In which period did the number of species increase most rapidly?

0 to 20 years
20 to 40 years
40 to 60 years
60 to 100 years
100 to 160 years

0 to 20 years

What factor is most likely to have caused the change in the number of bird species that occurred between years 30 and 60?

evolution of new bird species
decreasing food supply
increasing number of bird habitats
increasing competition among bird species

increasing number of bird habitats

Which of the following statements best describes the bird populations during the period from 100 to 160 years?

The number of species slowly increased, while the number of breeding pairs reached a peak and then slowly declined.
The number species declined slightly, while the number of breeding pairs reached a peak and then declined.
Both the number of species and the number of breeding pairs were stable.
The number of species slowly reached a peak and then slowly declined, while the number of breeding pairs slowly increased.

The number of species slowly increased, while the number of breeding pairs reached a peak and then slowly declined.

The climax, or final stage, of old-field succession is an oak-hickory forest, which is usually well established after 160 years. What happens to the diversity of bird species after 160 years?

The number of species slowly increases, while the number of breeding pairs slowly declines.
Both the number of species and the number of breeding pairs remain stable.
The number of species remains stable, while the number of breeding pairs slowly declines.
The answer cannot be determined from this graph.

The answer cannot be determined from this graph.

What does the y-axis show?

relative frequency of forest fires between 1700 and 1988
time, in 50-year intervals
percentage of landscape occupied by a forest stage
total area occupied by a forest stage, in square miles

percentage of landscape occupied by a forest stage

What does the red graph line represent?

old-growth stage
establishment stage
transition stage
thinning stage

thinning stage

During which period were forest fires most extensive?

1700-1750
1750-1800
1800-1850
1850-1900

1700-1750

In 1770, how much of the landscape did the thinning stage occupy?

15%
25%
50%
50 square miles

50%

Which of the following best describes the Yellowstone Plateau landscape in 1900?

More than half of the landscape was covered by forests made up of mature shade-tolerant trees.
Most of the landscape was occupied with forests made up of young lodgepole pines.
All of the forest stages occupied about the same amount of area.
More than half of the landscape was occupied by forests in which shade-tolerant trees were becoming established.

More than half of the landscape was occupied by forests in which shade-tolerant trees were becoming established.

Is this statement supported or not supported by the graph?
Between 1700 and 1985, the dominant forest stage on the Yellowstone Plateau progressed from establishment stage to old-growth forest, in a pattern typical of secondary succession.

supported
not supported
cannot be determined from the graph

supported

After the 1988 fires, scientists made careful observations of the changes on the Yellowstone Plateau. (The data they collected is not shown on this graph.) Given the historical data concerning succession and disturbance (fires), predict how the landscape in 2000 compared to the pre-1988-fire landscape.
Which statement is most likely to have described how the landscape changed in the 12 years after the 1988 fires?

The percentage of the landscape in old-growth stage forest increased.
The percentage of the landscape in old-growth stage forest stayed the same.
The percentage of the landscape in old-growth stage forest decreased.
It is not possible to make a prediction based on the data in this graph.

The percentage of the landscape in old-growth stage forest decreased.

The directional change in community structure through time is called __________.

succession
serial change
modification
a sere
cessation

succession

Which of the following statements about a common trait of late successional species is true?

Late successional species tend to be small and have high growth rates.
Pioneer species are K-strategists, whereas late successional species are r-strategists.
Late successional species tend to have high reproductive rates.
Late successional species tend to be excellent competitors.
Late successional species tend to have excellent dispersal abilities.

Late successional species tend to be excellent competitors.

A volcanic island in the middle of the Pacific Ocean explodes, and all life is removed from the island. However, decades later, the island has a covering of plant life, and some animals have appeared. This is an example of __________.

secondary succession
bog succession
primary succession
assimilation
old-field succession

primary succession

Pioneers are able to tolerate the harsh conditions that frequently follow disturbance. Under the facilitation model, pioneers __________.

prevent the establishment of later successional species
remain in the system as core species
adapt to changing conditions
settle into an equilibrium at K⁄2
are replaced by later successional species

are replaced by later successional species

What is the resource-ratio hypothesis?

There is a pattern of changing allocation of carbon to aboveground and belowground tissues.
There are three strategies in terms of resource use by plants.
Late successional species are not affected by species of previous stages.
The process of succession is determined by who gets there first.

There is a pattern of changing allocation of carbon to aboveground and belowground tissues.

Which of the following statements about changes in species diversity during succession is true?

Patterns of diversity are decoupled from patterns of environmental conditions.
Diversity tends to peak very early in succession.
Diversity reaches its peak at the climax community.
Diversity peaks are associated with transitions in species composition.
Comparing groups of sites, known as temprosequences, that are at different stages of succession can give insights into changes in diversity through succession.

Diversity peaks are associated with transitions in species composition.

Global climate change in the future is likely to cause __________.

little change to natural communities
large-scale changes to communities over long periods, with some species benefiting and others negatively affected
increased ranges for all species
negative impacts on all species
communities to change dramatically as species respond to autogenic changes

large-scale changes to communities over long periods, with some species benefiting and others negatively affected

Paleoecology could be used to answer all of the following questions with one EXCEPTION. Choose the EXCEPTION.

Compare the rate of distribution expansion of different species of trees.
What was the distribution of key plant species after the last glaciation event?
the exact relationship between plant and animal species that coexisted 1000-15,000 years ago
Determine the expansion or reduction of ranges of species 1,000 years ago.
Compare animal species distributions and plant species distributions.

the exact relationship between plant and animal species that coexisted 1000-15,000 years ago

The organismal concept of communities argues that species distributions along environmental gradients form clusters because they are interdependent.

True
False

True

Recent data indicate what regarding forests in eastern North America?

no change over the past 200 years
a decline in forested area in the past 50 years
no change in the past 50 years
a steady increase in forest since the late 1800s

a decline in forested area in the past 50 years

How much more timber was removed from "other private" lands versus "national forest" land?

twice as much
ten times as much
one hundred times as much
about the same

ten times as much

Which type of land lost the largest proportion of its timber in 1996?

other public
national forest
forest industry
can’t answer with the available information
other private

can’t answer with the available information

For which type of land is the total volume of forest (in cubic feet) decreasing?

forest industry
other public
other private
national forest

forest industry

Which of the following statements is/are accurate based on the information in this graph?

Lands other than forest industry land appear to be managed to produce net forest growth.
Overall, U.S. forest land is experiencing net growth as of 1996.
National forest land had the greatest growth relative to the amount of harvesting.
All of the above.
None of the above.

All of the above.

Which world region experienced the largest change in forested land between 1990 and 2000?

Europe
West Asia
Africa
South America
North America
Asia

Africa

Which of the following statements is/are accurate based on the information in this graph?

The information in this graph is consistent with the information in the graph of harvesting and growth in U.S. forests from Step 2.
Loss of forested land appears to be greater in the developing world than in the developed world.
The world overall is experiencing a net loss of forest.
All of the above.
None of the above.

All of the above.

If you were plotting a graph of land use in eastern North America with time on the x-axis and percentage of U.S. land forested on the y-axis, which of the following properly describes the major trends that would be evident?

The line would show a slow but positive increase through time as new habitats were colonized by primary succession and slowly converted to forests.
The line would remain flat at approximately 60 percent forest coverage.
The graph would start in the 1600s with nearly 100 percent of the land in forest. The graph would show only a very slight decline until the late 1800s. Then the line would decline rapidly until the 1970s. The line would begin to have a positive slope in the 1970s that would continue at a moderate rate until today.
The graph would start in the 1600s with nearly 100 percent of the land in forest. The decline would continue until the late 1800s. The line would begin to have a positive slope in the early 1900s and would continue to rise until about 1975, when it would begin to decline a very slight amount.
The graph would start in the 1600s with nearly 100 percent of the land covered by forest. The decline would continue until the late 1800s. The line would begin to have a positive slope in the early 1900s and would continue to rise until the present.

The graph would start in the 1600s with nearly 100 percent of the land in forest. The decline would continue until the late 1800s. The line would begin to have a positive slope in the early 1900s and would continue to rise until about 1975, when it would begin to decline a very slight amount.

True or false? Biologists studied the effects of forest fragmentation by calculating the difference between the amount of plant biomass in the edges of forest fragments and the interiors of unfragmented forest.

True
False

True

Which size forest fragment would be most affected by habitat fragmentation over a given period of time?

1 hectare.
10 hectares.
100 hectares.
1000 hectares.

1 hectare

Which of the following statements about the effects of forest fragmentation on plant biomass and species diversity is true?

Large forest fragments (>1000 hectares) are not affected by edge effects and their species diversity is expected to be stable over a long period of time.
The loss of plant biomass correlates mostly with the death of understory plants.
Small forest fragments lose their species diversity at the same rate as large forest fragments.
The loss of plant biomass has a domino effect on other species that live in the forest fragment.

The loss of plant biomass has a domino effect on other species that live in the forest fragment.

Which of the following statements is true?

Disturbance results in a static mosaic across the landscape.
Small animals, such as insects, are largely affected by landscape patterns, and they do little to alter those patterns.
Human activities have minimal impacts on ecosystems.
Elephants are major agents of disturbance in Africa. Even relatively small animals can be major agents of disturbance.
Clear-cutting favors reproduction of shade-tolerant species.

Elephants are major agents of disturbance in Africa. Even relatively small animals can be major agents of disturbance.

Conservation efforts for the Florida panther face challenges common to many large predators, particularly that the amount of space needed for adequate habitat for recovery and conservation of the species is quite large. Which of the following is a way that conservationists could solve this problem in the somewhat densely populated state of Florida?

Establish many small parks or reserves.
Create wildlife overpasses and underpasses across highways in the panthers’ territories.
Establishfenced areas to protect the panthers.
Use traps to remove potential competitors of the Florida panthers.
Collect the panthers from the wild and preserve them in one or more zoos.

Create wildlife overpasses and underpasses across highways in the panthers’ territories.

You are examining the distribution of pollination behavior of bees in different landscapes. You note that in some landscapes with many close patches of forest connected by wooded fence lines, the bees move readily from forest to forest, harvesting pollen in multiple patches, and they produce a much greater yield of honey. In other areas where there are large open tracts of farmland between forests, the bees must fly along a single corridor of riparian forest in order to reach the different forests, and they produce far less honey. Which of the following is an appropriate conclusion from your study?

Honey production depends on access to rivers.
Foraging success (as measured by honey production) is positively correlated with patch connectivity.
Patches that are closer together seem to increase competition, thus reducing honey production by the bees.
Bees foraging behavior is not affected by habitat connectivity.
Open tracts of farmland provide important flyways for the bees.

Foraging success (as measured by honey production) is positively correlated with patch connectivity.

Which of the following statements about habitat borders and transitions is FALSE?

Species diversity in edges is influenced by the degree of contrast between adjacent habitats.
Borders can create difficulties for some species that inhabit them.
Species diversity tends to be lower in edge habitats.
Species found only in edge habitats are called edge species.
Border habitats are unique habitats that offer easy access to adjacent habitat types.

Species diversity tends to be lower in edge habitats.

True or false. The y-axis of a species-area curve indicates the number of species that can be maintained in a specified area of habitat; currently, precise estimates are only available for vertebrates and plants in tropical rain forests.

False
True

True

Use the species-area curve in the tutorial to determine the percentage of vertebrate species that will be lost if the forest’s land area is reduced from 6,000 km 2 to 2,000 km2

20 percent of the vertebrate species will be lost.
All of the vertebrate species will be lost.
None of the vertebrate species will be lost.
80 percent of the vertebrate species will be lost.

20 percent of the vertebrate species will be lost.

How fast are tropical forests disappearing due to human activities?

0.5-1 percent per year
1-2 percent per year
4-5 percent per year
5-10 percent per year

1-2 percent per year

True or false. Habitat destruction generally progresses along the borders of a forest, which are the most accessible to new colonists.

True
False

True

Which size forest fragment would be most affected by habitat fragmentation over the longest period of time?

10 hectares
100 hectares
1 hectare
1000 hectares

1 hectare

Which of the following events would not affect habitat degradation at the border regions of a fragmented forest?

Spread of predators into surrounding farmland
Introduction of exotic species from the surrounding farmland
Overexploitation of wildlife
Increased pollution

Spread of predators into surrounding farmland

Which of the following is not thought to be accomplished by corridors?

They promote the reestablishment of locally extinct species.
They increase gene flow.
They have often been used in conservation biology.
They decrease species diversity.
They help to facilitate movement between connected patches of habitat.

They decrease species diversity.

Corridors are important for all of the following except __________.
Hints

highly mobile species
edge species
isolated populations
species with large home ranges
sessile species

sessile species

Which of the following does not correctly complete the sentence?
The butterflies that Dr. Haddad studies __________.

require a narrow range of resources
have well-defined life histories
are relatively easy to study
are studied at large spatial scales
require a large patches of habitat

require a large patches of habitat

Why did Dr. Haddad remove all trees from his experimental habitat patches and then burn the cleared area before starting his study?

This is the only way to test the effects of corridors on species movement.
This was required by the U.S. Forest Service, with whom he was partnered.
To create early successional habitat, which the butterflies prefer.
The mark-recapture method he used required it.
Butterflies prefer recently burned habitat, since it is high in essential nutrients.

To create early successional habitat, which the butterflies prefer.

Which of the following is not a result of this study?

Corridor length was a not a factor in how they were used by the butterflies.
Neither butterfly species was more likely to move to winged patches than to rectangular patches.
The size and shape of a habitat patch is more important than the presence or absence of a corridor.
Butterflies are more likely to move from center patches to connected patches of habitat (those with corridors) than to unconnected patches.
The presence of a corridor facilitated the movement of both butterfly species between connected patches of habitat.

The size and shape of a habitat patch is more important than the presence or absence of a corridor.

When studying forests undergoing secondary succession, your team was tasked with assessing the effect of distance from other, older forests on the number of species that became established in the patches. Which of the following would be a correct description of the graph of your likely results? Mean distance from older forests is on the x-axis, and number of species in the patch is on the y-axis.
Hints

The graph would start with low values of species richness at low values for distance to the nearest older forest, and then it would follow a positive parabolic relationship, initially maintaining low values for species richness with a steep increase after a certain threshold distance.
The graph would start with high values of species richness and low values for distance to the nearest older forest, and follow an inverse relationship with higher distances to the nearest forest having lower species richness.
The graph would start with high values of species richness and low values for distance to the nearest older forest, and then it would follow an inverse parabolic relationship, initially maintaining high values for species richness with a steep decline after a certain threshold distance.
A flat line beginning with the species richness that was set by the successional stage.
The graph would start with low values of species richness at low values for distance to the nearest older forest, then it would continue to increase in a direct relationship to ultimately have the highest species richness at the highest mean distance to the nearest older forest.

The graph would start with high values of species richness and low values for distance to the nearest older forest, and follow an inverse relationship with higher distances to the nearest forest having lower species richness.

What information is presented on the y-axis?

the number of species per island
the rate of immigration or extinction
the distance from the mainland
the size of the island

the rate of immigration or extinction

What does the top red graph line represent?

the rates at which species immigrate and become extinct on an island that is close to the mainland
the rate at which species become extinct on a small island
the rate at which new species immigrate to an island that is close to the mainland
the rate at which new species immigrate to an island that is distant from the mainland

the rate at which new species immigrate to an island that is close to the mainland

What kind of island has the highest rate of extinction?

a small island
a large island
an island that is close to the mainland
an island that is distant from the mainland
cannot be determined from the graph

a small island

On what kind of island would new species be most likely to arrive?

a small island
a large island
an island that is close to the mainland
an island that is distant from the mainland
cannot be determined from the graph

an island that is close to the mainland

The number of species on an island is at equilibrium when the rate of immigration is equal to the rate of extinction. This is shown on the graph by the points where each green and red line cross.
What kind of island is likely to have the highest number of species?

a small island close to the mainland
a small island distant from the mainland
a large island close to the mainland
a large island distant from the mainland
cannot be determined from the graph

a large island close to the mainland

The equilibrium theory of island biogeography predicts that large islands close to the mainland will have more species than small islands that are distant from the mainland.
Which of the following factors does not contribute to that prediction?

Large islands support larger populations than small islands. Small populations are more likely to go extinct.
It is easier for a species to reach an island that is near the mainland than one that is distant.
A large island is likely to have greater geographic diversity than a small island, making it more likely that newly arrived species will find appropriate habitats.
Evolution occurs more rapidly on large islands, thereby increasing species diversity.

Evolution occurs more rapidly on large islands, thereby increasing species diversity.

Which of the following statements best describes the trend in the species versus island area data?

The increase in number of species with increasing land area slows for larger islands, suggesting that there may be a maximum number of species an island can hold regardless of size.
There is a decreasing trend in species number as island size increases.
The number of species on an island increases by roughly 30 for every 5000-square-mile increase in land area.
There is no detectable influence of island size on number of species.

The increase in number of species with increasing land area slows for larger islands, suggesting that there may be a maximum number of species an island can hold regardless of size.

Roughly five orders of magnitude separate the smallest and largest islands on the log plot. How many orders of magnitude separate them on the standard plot?

5
1
10
2

5

If another island were present in the Caribbean that was about 1000 square miles in size, how many species of amphibians and reptiles would you expect to find on it? Choose the most likely number from the options below.

5
9
90
19

19

Adjust the immigration rate curve so that its maximum value (on the Y-axis) is 4. Adjust the extinction curve so that its maximum is 2. Choose the number below that is closest to the predicted number of species on this island.

75
25
40
50
60

60

Imagine a chain of islands of the same size that are at increasing distances from a mainland. The immigration rate should be highest for islands close to the mainland because they should receive the most colonizers. The extinction rate should be the same for all these islands. Use the equilibrium model of island biogeography to predict how the number of species on an island changes with distance from a mainland. Select the statement below that best represents your prediction.

The number of species increases with distance from the mainland.
The number of species increases as island size increases.
Immigration and extinction rates balance out so that there is no change in species number with distance from the mainland.
The number of species decreases with distance from the mainland.

The number of species decreases with distance from the mainland.

At the regional, or metapopulation, scale, population growth and regulation is determined by __________.

emigration
demographic processes
stochastic processes
dispersal, extinction, and colonization
environmental fluctuation

dispersal, extinction, and colonization

Which of the following statements about metacommunities is FALSE?

Metacommunities involve the dispersal by at least some of the species to link interactions among the sites.
The basic focus in metacommunity theory is to examine what regulates the co-existence of multiple species in that same system of connected habitat patches.
Metacommunities involve multiple patches at which interaction might occur.
Metacommunities involve multiple potentially interacting species.
Metacommunity dynamics will not affect individual populations’ extinction or colonization probability, rather they will affect the community as a whole.

Metacommunity dynamics will not affect individual populations’ extinction or colonization probability, rather they will affect the community as a whole.

Gaps are small scale disturbances in a forest caused by a few or many trees falling. Which of the following statements about gaps is FALSE?

Gaps in forests are quickly colonized by shade-intolerant, early successional species.
Gaps in forests decrease diversity.
Small-scale disturbances change the biological and physical composition of the forest.
Unlike large-scale disturbances, gap formation does not result in a complete change in a patch.
The microclimates of gaps differ from the forest surrounding them.

Gaps in forests decrease diversity.