Ch.17- Succession and Stability

Question 0

Disturbance

Answer 0

any process that destroys or removes biomass
-can cause marked changed in a community or population
~ex: forest fire, falling tree, hurricane

Question 1

Succession

Answer 1

change in communities following creation of new substrate or a disturbance

Question 2

Primary succession

Answer 2

occurs on bare land, where no living organisms are present
-after dramatic, large scale disturbance
-only newly formed habitat
Ex: volcano

Question 3

Secondary succession

Answer 3

regeneration of a community after a minor disturbance
-any type of disturbance that is not catastrophic
Ex; tree falls, lightning struck tree

Question 4

Pioneer community

Answer 4

the first community to be established after a disturbance

Question 5

Climax community

Answer 5

the communities that occur in late succession generally have stable populations

-communities generally move form r-selected to K-selected species

Question 6

succession involves changes in

Answer 6

-biomass, primary production, respiration, nutrient retention, biodiversity, other species specific community and ecosystem characteristics

Question 7

Facilitation Model

Answer 7

early species modify environment to aid colonization of later species
-Ex: legumes nitrifying the soil

Question 8

Inhibition Model

Answer 8

early species my modify environment that hinders colonization of later species
Ex; grasses spreading

Question 9

Tolerance model

Answer 9

Later species are not affected by earlier species

Ex: species filling different niches

Question 10

Alternative Stable States

Answer 10

different communities develop at the same location under similar environmental conditions

Question 11

Hysteresis

Answer 11

the inability to shift back original community type, even when conditions are restored

Question 12

Current view on succession

Answer 12

• The best communities are not necessarily climax communities
• Some species only exist in early-successional stages
• ecosystem services can be lower in climax stages
• Climax communities can change though time

Question 13

Intermediate disturbance hypothesis:

Answer 13

-community diversity should be greatest at intermediate levels of disturbance
~Low disturbance-> Competitive exclusion
~High disturbance-> high mortality

Question 14

Test of IDH:

Answer 14

• communities growing on boulders in the intertidal
  ~Large boulders-rarely rolled (Low disturbance) -> Low diversity
  ~ Middle-size-sometimes rolled-> High Diversity
  ~ Small boulders-rolled often(high disturbance)-> Low diversity