Lecture 16: Communities: Succession

Question 1

define succession

Answer 1

The sequence of community changes that is initiated by and following a major disturbance or the creation of new land

Question 2

Exact community composition is dynamic, but overall structure is relatively ____ in the ________.

Answer 2

• stable
• absence of major disturbance

Question 3

define climax community

Answer 3

• The community that results from succession
• what we typically think of as the dynamically stable community.

Question 4

Successional process is initiated by, and largely defined by, the succession of the _______

Answer 4

primary producers

Question 5

define primary succession

Answer 5

The establishment and development of communities in newly formed or disturbed areas devoid of life

Question 6

define secondary succession

Answer 6

Regeneration of communities from a disturbed state.

Question 7

what is the foundation of succession

Answer 7

primary producers

Question 8

What determines species presence in a successional stage of a successional sequence?

Answer 8

• How well it can colonize a newly disturbed area
• How it responds to environmental (abiotic and biotic) changes during succession

Question 9

Different species can vary greatly in their __________ in a given successional sequence

Answer 9

capacity (i.e. adaptations) to colonize and persist

Question 10

A variety of _________ can also shape the successional sequence

Answer 10

species interactions

Question 11

define inhibition

Answer 11

• The presence of one species reduces the probability of establishment by another species
• typically competition that may shift in balance as succession proceeds

Question 12

define facilitation

Answer 12

Processes where the presence of one species increases the probability of a second species becoming established

Question 13

facilitation - examples

Answer 13

• nurse tree (commensalism)
• ecosystem engineer (commensalism)
• mutualistic partner
• host species for parasite.

Question 14

define priority effect

Answer 14

• The outcome of an interaction between two species is determined by which one becomes established first
• early advantage impacting outcome of competition

Question 15

define tolerance

Answer 15

The persistence of a species through a successional sequence is not influenced by its interactions with other species, only its interactions with the environment.

Question 16

progression from early to late succession growth-forms

Answer 16

this progression changes light, temperature, soil moisture, and nutrient conditions

Question 17

growth forms in late succession

Answer 17

large growth forms begin to dominate, environmental change slows, and the successional sequence arrives at a climax state.

Question 18

Final biomass in a community is ___________, independent of what happened during the successional sequence.

Answer 18

limited by regional climate

Question 19

Community composition can _______ once a climax state has been reached at the end of a succession — the ______ we have been looking at so far

Answer 19

• continue to change slowly
• dynamic stable state

Question 20

define transient climaxes

Answer 20

successional sequence, followed by climax and collapse of communities that happens on a regular cycle

Question 21

what are successional gaps within climax communities defined by?

Answer 21

• patchwork structure of climax and other successional stages
• potentially maintains higher diversity within the community.

Question 22

what promotes the overall diversity of the community?

Answer 22

Simultaneous presence of successional and climax species

Question 23

Many ______ start an invasion from disturbed areas and are _________.

Answer 23

• invasive species
• early succession specialists

Question 24

Mutualistic and antagonistic soil fungi and other organisms can drive the success of plant invasion, if there is ________ and ________.

Answer 24

• chance facilitation
• absence of inhibition

Question 25

________ may also facilitate invasion, especially in human-modified landscapes

Answer 25

Sustained disturbance

Question 26

succession and invasive species - what happens when there is no sustained disturbance

Answer 26

many invasions would fall to low abundance or disappear

Question 27

early vs late succession - number of seeds

Answer 27

- early: many - late: few

Question 28

early vs late succession - seed size

Answer 28

- early: small - late: large

Question 29

early vs late succession - mode of dispersal

Answer 29

- early: wind or stuck to animals - late: gravity or eaten by animals

Question 30

early vs late succession - seed viability

Answer 30

- early: long (presence in seed bank) - late: short

Question 31

early vs late succession - root:shoot ratio

Answer 31

- early: low - late: high

Question 32

early vs late succession - growth rate

Answer 32

- early: fast - late: slow

Question 33

early vs late succession - size at maturity

Answer 33

- early: small - late: large

Question 34

early vs late succession - shade tolerance

Answer 34

- early: low - late: high

Question 35

describe the consistent pattern in species richness that succession creates

Answer 35

Early, rapid increase in richness followed by a late succession plateau and slight decline in the climax community

Question 36

why is there a slight decline in the climax community

Answer 36

- it hits the carrying capacity and overshoots - the decline is the die-off period

Question 37

Successional changes in plant community shifts the habitat, driving _______ in animal communities

Answer 37

associated changes