Chapter 19

Question 1

Succession

Answer 1

the process by which the species composition of a community changes over time

Question 2

Seral stage

Answer 2

each stage of community change during succession.

Question 3

Pioneer species

Answer 3

the earliest species to arrive at a site; typically are

able to disperse long distances and arrive quickly at disturbed sites.

Question 4

Climax community

Answer 4

the final seral stage in the process of succession; generally composed of organisms that dominate in a given biome.

Question 5

Chronosequence

Answer 5

a sequence of communities that exist over time at

a given location.

Question 6

Carbon dating

Answer 6

can be used to identify the age of the pollen in each layer, and helps to determine the changes in plant species composition around the lake over hundreds or thousands of year.

Question 7

Primary succession

Answer 7

the development of communities in habitats that are initially devoid of plants and organic soil, such as such dunes, lava flows, and bare rock.

Such habitats are colonized by species that require no soil (e.g., mosses) and can live on rock surfaces (e.g., drought- tolerant grasses).

Early colonizers produce organic matter that helps in the creation of soil that generates more hospitable conditions for other species.

Question 8

Secondary succession

Answer 8

the development of communities in disturbed habitats that contain no plants but still contain organic soil (e.g., plowed fields, forests uprooted by a hurricane).

Question 9

Facilitation

Answer 9

a mechanism in which one species increases the probability that a second species can become established.

Question 10

Inhibition

Answer 10

a mechanism in which one species decreases the probability that a second species will become established (e.g., by competition, predation, or parasitism).

Question 11

Priority effect

Answer 11

when the arrival of species at a site affects the colonization of other species; often occurs through inhibition.

Question 12

Tolerance

Answer 12

a mechanism of succession in which the probability that a species can become established depends on its dispersal ability and its ability to persist under the physical conditions of the environment.

Question 13

Transient climax communities

Answer 13

a climax community that is not persistent; occurs when a site is frequently disturbed so a climax community cannot persist.

Question 14

Small-scale disturbances in an area with a climax community can…

Answer 14

allow growth of species that are not considered climax species.

Question 15

Fire-maintained climax community

Answer 15

a successional stage that persists as the final seral stage due to periodic fires.

Question 16

Grazer-maintained climax community

Answer 16

when a successional stage persists as the final seral stage due to intense grazing.

Grazers preferentially consume the most palatable plants, leaving behind less palatable or better-defended species.