PCB 3043 Chapter 19

How can scientists study long-term patterns of succession of plant communities in a short amount of time? -By studying communities using a chronosequence. -By measuring the depth of the soil in a specified area. -By picking a dominant plant species and measuring the number of old individuals and young individuals. -By observing a plant community for a few month and documenting any changes.

-By studying communities using a chronosequence.

Scientists measured the fish species in three streams, Communities 1, 2, and 3. Jaccard's index of similarity, J, for Communities 1 and 2 is 0.33, for Communities 2 and 3 is 0.44, and for communities 1 and 3 is 0. What conclusion can be drawn about the stream communities from these data? -Communities 1 and 3 share all of the same species, whereas community 1 and 2 share fewer species. -Communities 1 and 2 are the most similar, whereas communities 1 and 3 are the least similar. -Communities 1 and 3 are the most similar, whereas communities 2 and 3 are the least similar. -Communities 2 and 3 are the most similar, whereas communities 1 and 3 share no species.

-Communities 2 and 3 are the most similar, whereas communities 1 and 3 share no species.

What are the limitations of using chronosequences to document patterns of ecological succession? -Not all areas have lakes containing a clear pollen record that shows how succession progressed. -Some sites lack a complete written record of direct observations of successional changes through time. -Localized damage to a site often results in a successional stage that is different from other sites of similar age. -Changes in abiotic conditions over time can produce a different sequence of successional stages.

-Localized damage to a site often results in a successional stage that is different from other sites of similar age. -Changes in abiotic conditions over time can produce a different sequence of successional stages.

Why should we not expect a single climax community to form on reclaimed coal mines located in the same geographic area? -Phosphorous-rich soils in reclaimed mines that also contain arbuscular mycorrhizal fungi support more climax species. -Ongoing environmental changes and differences in abiotic conditions affect climax plant growth on each coal mine. -The barren soil of a reclaimed coal mine can only support early-succession species and climax communities rarely form. -Natural succession on a reclaimed coal mine produces a more diverse climax community than seeding the reclaimed site.

-Ongoing environmental changes and differences in abiotic conditions affect climax plant growth on each coal mine.

What is one difference between primary and secondary succession? -Primary succession can start from bare rock; secondary succession starts from organic soils. -Trees are often the first colonizing species in primary succession, but trees are never the first species in secondary succession. -Primary succession is always caused by human disturbances; secondary succession is not. -Primary succession occurs in habitats with rich organic soil; secondary succession does not.

-Primary succession can start from bare rock; secondary succession starts from organic soils.

A small pond may gradually convert to a terrestrial environment. How does species richness change over time in a pond going through succession? -Species richness rapidly decreases at early stages, then remains constant. -Species richness increases at first, then slows and gradually declines over time. -Species richness fluctuates between rapid increases and sharp declines. -Species richness increases slowly at first, then reaches a plateau where it remains.

-Species richness increases at first, then slows and gradually declines over time.

Which characteristic would allow a plant species to occupy the earliest seral stage of primary community succession? -Germinate in constant, deep shade. -Develop a long taproot. -Grow in dry, drought-prone habitats. -Survive without organic soil.

-Survive without organic soil.

How is an insect community feeding on decomposing animal remains similar to a transient climax community? -The insect community will be displaced by competitors that occupy the remains moving forward. -The insect community will be unable to perpetuate itself once the remains are fully decomposed. -The insects form the pioneer community because they are the first organisms to occupy the remains. -The insects will persist indefinitely because climax communities are more stable and longer lasting.

-The insect community will be unable to perpetuate itself once the remains are fully decomposed.

What does the variable X represent in the equation for Jaccard's index of similarity? -The number of species not shared between two biological communities. -The number of species in community X. -The total number of species for both community A and community B. -The number of species shared between two biological communities.

-The number of species shared between two biological communities.

What does Jaccard's index measure? -The similarities and dissimilarities in species composition between two biological communities. -The mean number of species for two biological communities. -The similarities and dissimilarities in species richness and evenness of two biological communities. -The species diversity of a biological community.

-The similarities and dissimilarities in species composition between two biological communities.

What is a defining characteristic of pioneer species? -They reproduce rapidly. -They are slow-growing. -They cannot disperse very far. -They each produce a single, large seed.

-They reproduce rapidly.

A fire burns an Appalachian hardwood forest to the ground, leaving only bare soil. Sequence the plant communities in the order that they would be most likely to colonize the area.

-Well-developed, bare soil. -Annual herbaceous plants, such as crabgrass, ragweed, and horseweed. -Perennial herbaceous plants, such as asters, goldenrod, and Queen Anne's lace. -Shrubs and pine trees, such as loblolly pine and Virginia pine. -Fast-growing hardwood trees such as yellow poplar and red maple. -Dominant canopy of oak and hickory trees.

Jaccard's index of similarity, J, ranges between 0 and 1. J = X/(A+B+X) When is J equal to 1? -When none of the species are shared between communities A and B. -When none of the species are unique to community A or B. -When the number of species in communities A and B are equal. -When the number of species unique to community A is larger than the number of species unique to community B.

-When none of the species are unique to community A or B.

Scientists measured the fish species in three streams, labeled Communities 1, 2, and 3. The data are present in the table. An 'X' in the cell indicates that this species is found in this community. Calculate Jaccard's index of similarity for communities 1 and 3. -1.00 -0.33 -0.00 -0.44

0.00

Scientists measured the fish species in three streams, labeled Communities 1, 2, and 3. The data are present in the table. An 'X' in the cell indicates that this species is found in this community. Calculate Jaccard's index of similarity for communities 2 and 3. -0.44 -0.22 -1.00 -0.33

0.44

Local disturbances can create gaps in a climax community. A single tree falling in the forest creates a small gap, whereas a wind storm could blow down many trees, creating a large gap. The types of species that fill the gap depend on the size of the gap. A small gap favors ___________________. A large gap favors ___________________.

A small gap favors LATE-SUCCESSION SPECIES WITH LARGE SEEDS THAT GROW WELL IN SHADE. A large gap favors EARLY-SUCCESSION SPECIES WITH LIGHT, DURABLE SEEDS THAT GROW WELL IN SUN.

There are two explanations regarding how succession in shallow lakes and ponds can end in a terrestrial climax community. Sort each statement based on whether it describes the classic or modern explanation for succession in shallow lakes and ponds: Plants grow from the edges of the lake or pond towards the center of the water.

Classic

There are two explanations regarding how succession in shallow lakes and ponds can end in a terrestrial climax community. Sort each statement based on whether it describes the classic or modern explanation for succession in shallow lakes and ponds: The plants on the water's surface die, causing peat to accumulate in the lake or pond.

Classic

There are two explanations regarding how succession in shallow lakes and ponds can end in a terrestrial climax community. Sort each statement based on whether it describes the classic or modern explanation for succession in shallow lakes and ponds: The plants on the water's surface die, eventually filling the lake or pond in with peat.

Classic

In the context of ecological succession, classify each example as facilitation, inhibition, or tolerance: Nitrogen-fixing bacteria in alder roots increase the soil's nitrogen content.

Facilitation

In the context of ecological succession, classify each example as facilitation, inhibition, or tolerance: Plant roots growing in cracks in bare rock assist with soil formation.

Facilitation

In the context of ecological succession, classify each example as facilitation, inhibition, or tolerance: The deep shade under mature beech trees keeps birch tree seeds from sprouting.

Inhibition

In the context of ecological succession, classify each example as facilitation, inhibition, or tolerance: The dense roots of cogon grass outcompete other grasses for water and nutrients.

Inhibition

There are two explanations regarding how succession in shallow lakes and ponds can end in a terrestrial climax community. Sort each statement based on whether it describes the classic or modern explanation for succession in shallow lakes and ponds: A drought causes the lake or pond to go dry, exposing the sediments on the bottom.

Modern

There are two explanations regarding how succession in shallow lakes and ponds can end in a terrestrial climax community. Sort each statement based on whether it describes the classic or modern explanation for succession in shallow lakes and ponds: Plants begin to grow in the exposed sediment, covering the lake or pond basin.

Modern

There are two explanations regarding how succession in shallow lakes and ponds can end in a terrestrial climax community. Sort each statement based on whether it describes the classic or modern explanation for succession in shallow lakes and ponds: Water returns to the lake or pond, killing the plants on the bottom and eventually filling the basin with peat.

Modern

In the context of ecological succession, classify each example as facilitation, inhibition, or tolerance: Lichens can survive on bare rock surfaces where rotted plants cannot live.

Tolerance

In the context of ecological succession, classify each example as facilitation, inhibition, or tolerance: Oaks can sprout and grow in the dim light under pines and birches.

Tolerance