Succession Flashcards
What processes does succession encompass?
Change in:
-species dominance
-species evenness
-species diversity
-species composition
-soil properties
-nutrient flow
Why would a species establish or not?
Dispersal limitation
Niche requirements
Competition
Exploitation
Associated mutualists
What is chronosequence?
A series of communities or ecosystems representing a range of ages or times since disturbance
How long can succession take after glacial disturbances?
Centuries to millennia
What should site conditions for a chronosequence be?
Broadly similar, otherwise, the variability due to factors other than age will confound results
Why do we see changes in species composition?
Species have different adaptations that allow them to colonize, compete, and persist
How is aspen adapted to fire?
Stems burn in a fire
Underground roots can survive fire
Suckers can sprout fast after fire
How are jack pine and balsam fir adapted to fire?
Cones covered in pitch
When pitch burns, cones release seeds
How is fireweed adapted to fire?
High survival rate in the soil
Can form rhizomes and resprout after fire
How long does primary succession at a glacial bay take?
1500 years
How does secondary forest succession take?
200 years
How long does succession in intertidal communities take?
1.5 years
How long does succession in desert streams take?
Can occur on a scale of weeks
What is sedimentation?
The deposition of suspended matter onto lake bottom
What ecosystem properties can change during the course of succession?
Biomass
Primary production
Respiration
Nutrient retention
What ecosystem changes occur at Glacier Bay?
Increase in soil depth during succession
Proportion of organic and litter horizon increases with succession
Changes driven by biomass
What are the 3 models of mechanisms of succession?
Facilitation
Tolerance
Inhibition
What is the facilitation model to succession?
Early successional species modify their environment so that it becomes less suitable for them but more suitable for other species found in late-successional stages
Early successional species become locally extinct and late-successional spaces persist
What is the tolerance model to succession?
Pioneer species do not facilitate or inhibit other species
Community composition structure only by species dispersal and life-history traits
Climax composed of species that are most tolerant to site conditions and competition
What is the inhibition model for succession?
Early colonizers inhibit colonization by later arrivals until they are disturbed
