Succession

Which of the following would you expect to find in a primitive community?
a.
deer
b.
trees
c.
shrubs
d.
algae

D.

Succession occurs because _______.
a.
organisms gradually change the environment
b.
climax communities are not possible
c.
dominant organisms drive out pioneer species
d.
ecosystems never reach a sustainable point

A.

Which of the following statements about secondary succession is true?
a.
Secondary succession occurs in ecosystems that have no vegetation.
b.
Secondary succession affects ecosystems that are already established.
c.
Ecosystems require pioneer species to undergo secondary succession.
d.
Secondary succession can occur in areas without soil.

B.

Explain how human impact can lead to succession in ecosystems.

Student answers will vary. Possible answers include, human activity, such as logging and deforestation leading to succession. Large changes in the vegetation of an area can lead to loss of complex species through migration or starvation due to fewer resources. These ecosystems would have to undergo succession to recover the more complex species.

Primary succession ________.
a.
is caused solely by human events
b.
occurs on preexisting soil
c.
occurs in areas without soil
d.
becomes normalized by climax species

C.

How are primary and secondary succession similar and how are they different?

Primary and secondary succession occur after both human and natural events that cause drastic change in the makeup of an area. Primary succession occurs in areas where there is no soil and secondary succession occurs in areas where there is soil. Secondary succession can follow primary succession once pioneer species have contributed to the development of soil during primary succession. Secondary succession, however, can also happen without primary succession if an event caused extensive loss of plant and animal life without destroying the soil. One example of this is wildfires. Soil is not destroyed in these cases and therefore secondary succession can occur.

Compare primitive communities to climax communities.

Primitive communities are common in areas undergoing primary succession. They are composed of rocks, lichens, algae, and fungus. The primitive communities lead to the production of soil, which allows the community to proceed into the next phase of succession, where more complex organisms can be sustained. Once a community has developed soil, more plants can be sustained and animals can begin to return to the ecosystem. Eventually, the community reaches its climax. Climax communities are composed of a large variety of complex organisms. Climax communities are stable. Changes occur in climax communities, but the overall ecosystem remains in balance.

Explain how ecosystems are sustained through succession.

Succession allows ecosystems to recover from events. Even ecosystems that have no soil, such as those that have been destroyed by volcanic activity, can return to a stable and sustainable state. Primary succession occurs in these ecosystems. Pioneer species are found in areas undergoing primary succession. These pioneer species help reform soil over time. After soil is present, new species can move into an area during secondary succession. After a longer period of time, climax communities can be reached.

What are some possible causes of succession in ecosystems?

Student answers will vary. Possible answers include, overcutting, overhunting, farming, volcanoes, fires, windstorms, glaciation, and defoliation.

Succession is _______.
a.
harmful to ecosystems
b.
a natural recovery process
c.
unnecessary for ecosystem recovery
d.
a one-time event

B.