Lecture 16

Question 1

Disturbances are events that affect

Answer 1

The physical environment and therefore resource availability

Question 2

These events change community properties (such as:

Answer 2

Interactions among species and overall biodiversity

Question 3

Disturbances can be categorized as _______ or __________

Answer 3

Physical or biological

Question 4

Examples of physical disturbances

Answer 4

Glacial advance and retreat

Volcanic eruptions

Fire

Flood

Drought

Tornado

Question 5

Examples of biological disturbances

Answer 5

Bark beetle infestation

Root rot of fungus

Overgrazing

Algal blooms

Question 6

How is pollution categorized?

Answer 6

Chemical pollutants (physical), but human-caused (biological)

Question 7

Disturbance regime

Answer 7

A community’s disturbance regime is the historical pattern of different disturbances to which organisms in the community are adapted

Question 8

The disturbance regime of a Southern California forest would include:

Answer 8

Frequent drought and bark beetle infestation, and less frequent fire

Question 9

Novel disturbance

Answer 9

A new kind of disturbance to which organisms in a community are not adapted

OUTSIDE the disturbance regime

Question 10

Example of novel disturbance

Answer 10

Pollution

Question 11

Succession

Answer 11

Involved a directional change in the species composition of a community over time following a disturbance

Question 12

Primary succession

Answer 12

Occurs on substrate without soil, such as rock or lava

Severe disturbances such as a volcanic eruption or glacial retreat initiate primary succession

Question 13

Secondary succession

Answer 13

Occurs after a disturbance that has left the soil intact

Fires, floods, and abandoned farmlands initiate secondary succession

Question 14

After a severe disturbance, only a few certain _______ are able to colonize the disturbed site and initiate primary succession

Answer 14

Pioneer species

Question 15

Pioneer species are ____________ organisms

Answer 15

r-selected

Question 16

Pioneer species change:

Answer 16

The composition of the substrate, making it suitable for others to follow

Question 17

___________ are the most common pioneer species

Answer 17

Lichens and mosses

Question 18

Lichens and mosses convert the rock into soil that will support _____________-

Answer 18

Vascular plants with roots

Question 19

Vascular plants are more ________ than lichens and mosses

Answer 19

K-selected

Question 20

Once these new species begin to arrive, the original colonizers (the pioneer species) are ______________-

Answer 20

Less able to compete and are gradually eliminated

Question 21

Over time, the vegetation develops in a sequence of series/stages called

Answer 21

Seres

Question 22

First sere

Answer 22

The seral community

The early colonizing community of pioneer species following the disturbance

Question 23

Final sere

Answer 23

Climax community

The stable, self-perpetuating community that consists of (in a forest community) tree species such as pine or oak

Question 24

Between the seral and climax communities, there is frequently a __________ followed by a _________ followed by a sere with _____________-

Answer 24

Grass sere, shrub sere, sere with different tree species

Question 25

It is not just the __________- that changes during succession, but the _________________________ as well

Answer 25

Plant composition, composition of animals and microorganisms

Question 26

___________, in the early 1900s, described communities as ___________

Answer 26

Frederick Clements, “superorganisms”

Question 27

“Superorganisms”

Answer 27

All of the species in a community are equivalent to all of the interacting organs within an individual organism’s body

Succession represents a community developing “from infancy to maturity”

Question 28

____________ believed communities to be much more random

Answer 28

Henry Gleason

How often is a climax community (“maturity”) reached?

If there is another disturbance, the community must start over