Succession Flashcards
Succession
gradual change in plant and animal communities following a disturbance
3 ways ecological communities can respond to a disturbance
- Stability = no change
- Resistance = ability to maintain structure and func.
- Resilience = ability to recover after disturbance
Primary succession
-occurs on newly exposed geological substrates
Secondary succession
- follows disturbance that does not destroy all biological material
- much faster
- e.g. abandoned farm land
- e.g. fire, flood, landslide, human clearing
Hydrosere succession
-conversion of aquatic environments (plants take over)
climax community
-late in succession –> state of stability until next disturbance
Early succession
- rapid increase in species richness
- good colonizers (r-select)
- low survival (vulnerable to herbivores)
- not all groups increase in density throughout succession
Human disturbance
- biggest impact on communities world-wide
- terrestrial and aquatic
- typically reduce diversity
How long does colonization to climax take?
50-500 yrs
-ecological time (shorter than geologic or evolutionary)
-first stages can be seen during lifetime
-
Piedmont
-plain rich with nutrients that washed down from Appalachian Mt.s
crabgrass, horseweed, ragweed
years 1-2
Broomsedge, aster, wild carrot, goldenrod
years 3-5
Virginia pine, red cedar, black locust, sumac
years 5-15
closed pine forest
years 20-50
deciduous hardwoods (red maple and tulip poplar)
years 50-100
mixed deciduous forest with oaks, hickories, beech, and tulip poplars
years 100-300
-climax
What happened to bird species during Piedmont succession?
- not consistant
- habitat requirements of some species made early stages of succession favorable
- early birds were lost later
- eventually reached climax bird community
3 options that early species can do for later species after disturbance
- facilitate
- tollerate
- inhibit
example of facilitation
- macroalgae are early species in intertidal zones
- surf grass recruitment depends on their seeds hooking onto macroalgae
tolerance
- initial stages of colonization are not limited to pioneer species
- climax community is reached when tolerant species have been exhausted
inhibition example (and definition)
- climax community = long lived resistant species
- creosote bushes do allelopathy –> produce chemicals to discourage colonization around it
old field secondary succession
- inhibition in early stages
- facilitation in later stages
succession in streams
- flash floods wipe out algae and invertebrates
- some invertebrates escape bc they’re in aerial form
- took 2 months for predator population to recover
- algae came back first, then invertebrates
diversity in streams
- highly affected by most plentiful species: cryptolabis)
- when they live in water, diversity is low
- when they’re aerial, diversity is high
biomass accumulation model
- model that says forest ecosystems will go through distinct recovery phases
1. reorganization
2. aggregation
3. transition
4. steady state
reorganization
10-20 yrs
-forest loses biomass and nutrients
aggregation
100+ yrs
- ecosystem reaches peak biomass
transition
biomass declines from peak
steady state
biomass fluctuates around mean
Park Grass experiment
- long term study of fertilizer treatment effects
- 150 yrs
- Silverton used composition variability as measure of stability
- although stability is maintained, populations can change substantially –> depends too on resolution of study area
Chronosequence
- show long term change in ecosystem
- e.g. hawaiin islands, glacier bay, or krakatau
- patterns of nutrient dispersion change
Krakatau
- primary succession
- explosion killed everything!
- succession began with algae and insects (arthropods)
- of the 53 plants: 32 (60%) from ocean currents, 17 (32%) from wind, 4 (7%) from fruit eating animals or man
