Lecture 16: Communities: Succession Flashcards
define succession
The sequence of community changes that is initiated by and following a major disturbance or the creation of new land
Exact community composition is dynamic, but overall structure is relatively ____ in the ________.
- stable
- absence of major disturbance
define climax community
- The community that results from succession
- what we typically think of as the dynamically stable community.
Successional process is initiated by, and largely defined by, the succession of the _______
primary producers
define primary succession
The establishment and development of communities in newly formed or disturbed areas devoid of life
define secondary succession
Regeneration of communities from a disturbed state.
what is the foundation of succession
primary producers
What determines species presence in a successional stage of a successional sequence?
- How well it can colonize a newly disturbed area
- How it responds to environmental (abiotic and biotic) changes during succession
Different species can vary greatly in their __________ in a given successional sequence
capacity (i.e. adaptations) to colonize and persist
A variety of _________ can also shape the successional sequence
species interactions
define inhibition
- The presence of one species reduces the probability of establishment by another species
- typically competition that may shift in balance as succession proceeds
define facilitation
Processes where the presence of one species increases the probability of a second species becoming established
facilitation - examples
- nurse tree (commensalism)
- ecosystem engineer (commensalism)
- mutualistic partner
- host species for parasite.
define priority effect
- The outcome of an interaction between two species is determined by which one becomes established first
- early advantage impacting outcome of competition
define tolerance
The persistence of a species through a successional sequence is not influenced by its interactions with other species, only its interactions with the environment.
progression from early to late succession growth-forms
this progression changes light, temperature, soil moisture, and nutrient conditions
growth forms in late succession
large growth forms begin to dominate, environmental change slows, and the successional sequence arrives at a climax state.
Final biomass in a community is ___________, independent of what happened during the successional sequence.
limited by regional climate
Community composition can _______ once a climax state has been reached at the end of a succession — the ______ we have been looking at so far
- continue to change slowly
- dynamic stable state
define transient climaxes
successional sequence, followed by climax and collapse of communities that happens on a regular cycle
what are successional gaps within climax communities defined by?
- patchwork structure of climax and other successional stages
- potentially maintains higher diversity within the community.
what promotes the overall diversity of the community?
Simultaneous presence of successional and climax species
Many ______ start an invasion from disturbed areas and are _________.
- invasive species
- early succession specialists
Mutualistic and antagonistic soil fungi and other organisms can drive the success of plant invasion, if there is ________ and ________.
- chance facilitation
- absence of inhibition
________ may also facilitate invasion, especially in human-modified landscapes
Sustained disturbance
succession and invasive species - what happens when there is no sustained disturbance
many invasions would fall to low abundance or disappear
early vs late succession - number of seeds
- early: many
- late: few
early vs late succession - seed size
- early: small
- late: large
early vs late succession - mode of dispersal
- early: wind or stuck to animals
- late: gravity or eaten by animals
early vs late succession - seed viability
- early: long (presence in seed bank)
- late: short
early vs late succession - root:shoot ratio
- early: low
- late: high
early vs late succession - growth rate
- early: fast
- late: slow
early vs late succession - size at maturity
- early: small
- late: large
early vs late succession - shade tolerance
- early: low
- late: high
describe the consistent pattern in species richness that succession creates
Early, rapid increase in richness followed by
a late succession plateau and slight decline
in the climax community
why is there a slight decline in the climax community
- it hits the carrying capacity and overshoots
- the decline is the die-off period
Successional changes in plant community shifts the habitat, driving _______ in animal communities
associated changes
