Community Structure: Changes In Structure Over Time

Front 1

Succession:

Back 1

Directional and cyclic changes in communities. There is a degree of predictability to the progression of vegetation.

Front 2

R-Selected:

Back 2

Weedy species that APPEAR FIRST.

Front 3

K-Selected:

Back 3

Replace the weedy species when they die out.

Front 4

Seres:

Back 4

Different plant communities in a succession series.

Front 5

Stable Climax Community(Clements Idea):

Back 5

One that is in equilibrium - plants replace themselves with he same species and the relative abundance remains the same.

Front 6

Gleason's Idea:

Back 6

It is not predictable, it's all about chance (who gets there first)

Front 7

Primary Succession:

Back 7

Occurs on a new, sterile (no life) area. EXAMPLE: glaciers, lava.

LESS COMMON THAN SECONDARY.

Front 8

Secondary Succession:

Back 8

Occurs on disturbed sites, not sterile (still life). Usually top soil at the minimum is retained. EXAMPLE: land slides, plowing fields.

Front 9

Facilitational Model (processes that drive successional change):

Back 9

The early species in succession facilitates the arrival of the later species. Changes the environment to promote colonization of other things.

replacement is ORDERLY AND PREDICTABLE.

Front 10

Inhibition Model (processes that drive successional change):

Back 10

Development at any site depends on who gets there first. It will be able to suppress colonization by other things.

succession is LESS PREDICTABLE AND INDIVIDUALISTIC.

Front 11

Tolerance Model (processes that drive successional change):

Back 11

Any species can start it off. Some species may replace others because they are more tolerant of limiting resources.

Front 12

Random Colonization (processes that drive successional change):

Back 12

Null model, prediction of outcome against which you can statistically test your results.

colonization is RANDOM.

Front 13

Monoclimax Hypothesis (climax states):

Back 13

Every region has one ultimate climax community that other communities are working towards.

DETERMINED BY CLIMATE.

Front 14

Polyclimax Hypothesis (climax states):

Back 14

Many different climax communities recognized for a given area, controlled by:

Soil moisture

Soil nutrients

Activity of animals

Front 15

Climate Pattern Hypothesis (climax states):

Back 15

Not monoclimax or polyclimax, it's patches - continuum of different equilibrium states that track changes in the environment.

the endpoint will CHANGE GEOGRAPHICALLY OR WITH TIME.

Front 16

Patch Dynamics:

Back 16

Community as a whole moving toward a climax state, but patches in it may be experiencing cyclic changes.

Front 17

Reciprocal Replacement:

Back 17

Cyclic change of one tree species by another, over and over.