ecology test 4 CH 19

Why are there no spruces in the early seral stages of succession at Glacier Bay?

Spruce seeds are not likely to disperse to the pioneer and low-shrub stages.

A pioneer species is _____ species to arrive at a site.

THE FIRST

Why does succession in intertidal communities tend to happen faster than succession after a disturbance in terrestrial communities?

The generation time of dominant species in the intertidal zone is shorter than that of the dominant species in terrestrial habitats.

(Figure 19.14) If you excluded deer from the forest represented by the graph, what changes in importance would you likely see? CHART 4

Tulip poplars importance will increase in the understory.

Legumes contain nitrogen-fixing bacteria in their roots that increase soil nitrogen for use by other species. This is an example of

facilitation.

One of the traits common in late-succession plant species is

few seeds.

Experimental removal of a single species in a succession would:

help determine whether that species facilitated the growth of a later-succession species.

Inhibition is a mechanism of succession in which

one species decreases the probability that a second species will become established

35. Stream succession is rapid because

organisms can move downstream from less disturbed sites.

Chaparral vegetation found in southern California is an example of a climax community maintained by

periodic fires.

A climax community is generally composed of organisms

that dominate in a given biome.

The priority effect occurs when

the arrival of one species at a site affects the subsequent colonization of other species.

Succession in intertidal communities is rapid because

the generation time of the dominant species is shorter.

What information about species is needed to calculate Jaccard's index?

those present

Which mechanism of succession is independent of the presence or absence of other species?

tolerance

Some of the first species to colonize an area following disturbance have to persevere under inhospitable conditions such as disturbed soils, low soil moisture, and altered nutrient levels. This is an example of

tolerance.

A climax community that is not persistent is called a _____ climax community.

transient

When succession was studied at the Duke Forest in the Piedmont region of North Carolina, how many years did it take for the forest to revert to deciduous climax forest from agricultural field?

200 YEARS

61. Which of the following is NOT an example of inhibition?

A species acts as a nurse plant and increases water available to other species.

How could you tell for certain if a plant lived 2000 years ago in a pond sediment sample?

A) carbon dating of pollen

(Figure 9.12) In the experiment associated with the figure, acorn barnacles facilitate the growth of algae. If you removed both acorn barnacles and the limpet predators of algae, what would you be likely to observe over time? CHART 3

B) a carpet of little brown barnacles followed by algal growth

Which of the following is TRUE about succession?

Both a and b are true.

How are floods that remove organic matter on the surface of rocks similar to gaps observed in forests?

Both allow early-succession species to colonize.

11. A sequence of communities that exist over time at a given location is

C) a chronosequence.

To apply the concept of chronosequence, ecologists assume that:

C) older sites and younger sites have undergone the same disturbances.

The last seral stage in the process of succession is called the _____ community.

CLIMAX

Researchers have recently proposed a new way lake succession can occur. What is one feature of this new model?

Colonization of plants happens from the sediments at the lake bottom.

20. Over the course of terrestrial succession, what is the general pattern of species richness?

D) an increase that plateaus, followed by a slight decline

28. You observe three beech-maple forests in Indiana that began as ponds. How might you determine whether they all started succession with the same community composition?

D) sample the soils at each site for pollen and carbon-date them to get an estimate of the species that appeared first at the site

What is the clearest way to document succession?

DIRECT OBSERVATION

In deciduous forests of Pennsylvania, the climax community used to be composed of large trees of mostly oak, hickory, and tulip poplar, but over time the composition of the understory changed to sugar maple and beech. What was the cause of this shift?

Deer browsing caused reductions in species that were not browse tolerant.

Why might a forest contain both climax tree species and a few early-succession species?

Disturbances have produced gaps of intense sunlight.

What role does disturbance play in the recently discovered mechanism of pond succession that isn't found in the classical mechanism of succession?

Droughts lower water levels so that plants can colonize lake sediments.

Why do plants in early seral stages exhibit high levels of tolerance?

Early plants must deal with harsh conditions, such as fluctuating temperatures.

Why is tolerance a mechanism that can be found in both early and late seral stages?

Early seral species need tolerance of stressful environments, while late seral species need tolerance of deep shade.

In some areas of the western United States pines are an important part of the climax community. Fires occur at regular intervals in these areas. How could fire maintain these pine populations?

Fires kill understory species, allowing pine seedlings to thrive.

23. In primary succession of sand dunes, the first species to colonize are

GRASSES

73. In the study of Oregon intertidal communities, little brown barnacles (Chthamalus dalii) are first to colonize disturbed areas. Over time, the community is dominated by the acorn barnacle (Balanus glandula). Which mechanism of succession explains the relationship between the two species of barnacles?

INHIBITION

15. Why were wind- and sea-dispersed seeds the first to colonize and survive on Krakatau?

In the early days of colonization, there were no forests to attract animals that could disperse seeds.

27. If you were assigned the task of starting a plant community that could thrive on Mars, where there is no soil on the surface, which might be good to bring for the initial colonization?

LICHENS

Why must oxygen concentrations remain at low levels for pond succession to occur?

Low oxygen levels decrease decomposition rates, resulting in peat production.

Can you tell what plant seral state you are in by looking at the bird species in a given area?

No, because some bird species are associated with many plant seral stages.

14. Why might direct observation of succession be easier in intertidal communities than in terrestrial communities?

Organisms in an intertidal area have shorter generation times than organisms in terrestrial communities.

Each stage of community change during succession is called a _____ stage.

SERAL

The receding glacier at Glacier Bay in Alaska has been used to study

SUCCESSION

Why does secondary succession occur faster than primary succession?

Soil in secondary sites can contain plant seeds and roots.

31. Which is true about terrestrial succession?

The sequence of seral stages is variable.

(Figure 19.11) Given the results in the figure, what might prevent a tree with large seeds, like a chestnut, from establishing in a forest with high densities of sweet birch seeds, an early- succession species? CHART 2

The sweet birch seeds would germinate and grow faster, crowding out the chestnut saplings.

Look at how species richness increases and reaches a plateau in the figure. Why does the species richness level off? CHART 1

There isnt enough space on the boulders to accommodate more species.

When seeds of early- and late-succession species were raised under low light conditions similar to those found in the understory of mature forest, researchers found that species with _____ seeds had _____ seedling survivorship in shade.

There was no relation between seed size and seedling survivorship.

What characteristic shared by diatoms and cyanobacteria might make them good colonizers of nutrient-poor habitats?

They both photosynthesize light to make carbohydrates.

How do herbivores affect the outcome of succession in intertidal zones?

They forage on particular types of algae, allowing others to dominate.

What are the characteristics of plants found immediately after a drought in a pond?

They have low root-to-shoot ratios.

Why does stream succession rely less on how fast organisms can move themselves than terrestrial succession?

Water can carry organisms from less disturbed to more disturbed sites.

Which of the following is a pioneer species?

annual plants with small, light seeds

During succession, communities

are always changing

What kinds of disturbances might change climax communities on the steep slopes of the Rocky Mountains?

avalanches

Changes in North American forest climax communities

can occur but may happen very slowly.

The age of pollen grain is determined using

carbon dating.

Indirect observations of succession are often done by using

chronosequences and pollen.

Grazers can change climax communities because they

consume palatable plants.

A mechanism of succession in which the presence of one species increases the probability that a second species can become established is

facilitation.

In the Sonoran desert of Arizona, young saguaro cacti often begin life in the shade of mesquite trees; they usually die if they begin life in out in the open. This is an example of

facilitation.

Secondary succession takes place in habitats that _____.

d. have been disturbed and contain no plants but still contain organic soil.

In the study of stream succession following a major flood event at Sycamore Creek in Arizona, what was the first organism to recolonize the stream?

diatoms

8. Succession is best studied using

direct observations.

Succession studied at Glacier Bay, Alaska, and on the island of Krakatau, Indonesia, has been done using

direct observations.

What causes variation in climax communities over space?

environmental gradients

Invasion of cheatgrass (Bromus tectorum) in the western North America is maintained by

extensive grazing.

Which mechanisms of succession depend on one species arriving at a site before another species?

facilitation and inhibition

19.10) These graphs show that succession is associated with a rapid increase in species richness that slows and levels off over time. How might you explain a graph showing succession with an initial increase in species richness followed by a decline in species richness over time? CHART 1

inhibition

Electrical companies have discovered that dense shrub thickets, once established, can prevent growth of trees under power lines. Which mechanism of succession are these companies using by planting shrubs under power lines?

inhibition

Garlic mustard (Alliaria petiolata) is a common invasive species in the eastern United States. One mechanism that allows it to dominate in some areas is the production of chemicals that interfere with the ability of other plants to gain nutrients through mutualistic fungi. This mechanism is an example of:

inhibition.

Transient climax communities can occur when a site

is frequently disturbed.

Succession in aquatic environments

is often faster than succession in terrestrial environments.

In fire-maintained climax communities in the southeastern United States, periodic fires

kill oak and other broadleaf species but not pines.

Which type of succession would be expected to be the slowest?

lake

Late-succession species are likely to have

large seeds.

Terrestrial primary succession begins with

lichens and mosses.

Canopy gaps change local forest composition primarily by increased

light.

If a legume inhibits the growth of other plants around it by using noxious chemicals,

nitrogen will build up in the soil over time.

When considering the effect of one species on the probability of a second species becoming established, facilitation is_____, inhibition is _____, and tolerance is _____.

positive; negative; neutral

Development of communities in habitats that are initially devoid of plants and organic soil is known as _____ succession.

primary

Which of the following habitats could NOT undergo secondary succession?

severely burned forest

Which of the following is NOT a trait of a pioneer species?

shade tolerant

Jaccard's index quantifies

similarity between communities.

Succession is change in _____ over time.

species composition

Which of the following is NOT an example of a habitat that could undergo primary succession?

tree-fall gap

18. Primary succession

usually begins with lichens and mosses.

Which of the following is an example of a transient climax community?

vernal pool

When succession was initially observed on the islands of Krakatau, plants with _____ seeds dominated.

wind-dispersed

Early-succession species are likely to have

wind-dispersed seeds

Plants _____ should be used for initial seeding of abandoned strip mines.

with long seed viability