ecological succession Flashcards
what is ecological succession?
Gradual and steady change in structure of a community leading to biological community to evolve
What are “seres”
Individual successions
What are ‘seral stages’?
Developmental phases
Describe a complete food chain and its elements
Autotrophs - Herbivores - Secondary consumers
Web reaches equilibrium —> complex biotic community
Differentiate between autogenic and allogenic succession
Autogenic: internal stimulus change by organisms in biotic community
Allogenic: external stimulus change in biotic communities
What 2 elements affect autogenic succession?
1) pH/ soil fertility
Presently inhabit - change new plants - affect animal species
2) Mature trees = more shade
Sunlight-deficiency causes death
What 3 elements affect allogenic succession?
Triple C’s
1) Change in soil composition
Flood, silt deposits, chemicals deposits
2) Climate Change
Temp, weather, rainfall
3) Catastrophes
Volcano, hurricane, floods
Define ‘Primary Succession’
New, uncolonised habitat/ lifeless area, uninfluenced by pre-existing communities
Explain the Primary Succession Process
Rock surface hostile environment —> Pioneer (r-strat) colonise rock surface —> Chemicals secreted break down —> Pedogenesis occurs —> Organic matter decomposes —> Opportunistic species have soil and nutrients —> Climax populations are k-strat —> Stable complex biotic community
Define ‘Secondary Succession’
Succession after established biotic community has been destroyed
Explain the Secondary Succession process
Established biotic community co-exists —> Destruction of habitat —> Soil contains organic matter & seed nutrients —> Pioneer: (r-strat) —> Complex opportunistic species —> Climax populations are k-strat —> Stable complex biotic community
Differentiate between K-strategy and R-Strategy
R - K
Breeding: Once/ twice - Occasional
Offspring: Huge number - 2/ time (long gestation)
Mortality: High (OS don’t make to adulthood) - Low (adulthood & senility)
Maturity: Minimal parental care - Constant supervision
Species: Pioneer - Climax
How many types of survivorship curves are there? Explain the basic criteria
3 types:
Type 1: Low death rate, live to old age
Type 2: Moderate death rate
Type 3: High death rate, die young
What is a survivorship curve?
A survivorship curve on a graph shows the number of proportions of individuals surviving to each age for given species
What are 3 points for a Type 1 curve
- convex curve
- high survival probability in early middle life to rapid decline
- few species care well eg mammals
