1. Changes in Communities
Succession
Changes in Communities

2. What is Succession?
The orderly process of change over time in a community.
Occurs both on land and water

3. Primary Succession Succession in a newly formed area
Occurs in new lakes, ponds, cooled lava, sand dunes and bare rock
Takes place in areas that have never previously supported life
Ex - rock -> lichen -> moss -> grass -> shrub -> trees -> oak hickory forest

8. Secondary Succession
Sometimes an storms or fire destroy the species growing in a community.
Succession resumes again until there is a climax community.
Succession that occurs where an area has been disturbed.
Ex - grass -> shrub -> trees -> oak hickory forest

9. Secondary Succession
Human activities usually cause secondary succession.
Cutting for timber
Clearing for farming
Construction
Some Natural Causes
Forest fires
Volcanoes
Hurricanes
Tornados

10. Stages of Succession Pioneer Community First inhabitants of the area
r-strategists
Ex. Lichen and mosses

12. Sere
A set of communities that succeed one another over the course of succession at a given location
Succession from start to finish

13. Stage of Successsion
Seral Stages – stages at which species are replaced through competition
Ex – grasses, small herbs, shrubs, coniferous trees
Climax Community – final stage of succession.
Ecosystem has stopped changing
Reached a state of permanence

22. Climax Community High stability High species diversity
Complex food chains
K-strategists
Ex. oak - hickory trees

23. To sum up
During succession species modify the environment making it more suitable for new species
Pioneer species are often poor competitors and are replaced by stronger competitors with greater environmental demand
Later communities are more complex than the communities they replace.
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24. Zonation
The sub-classification of biomes into smaller zones that share unique physical characteristics.
A unique habitat that will favor various species will in turn exist in these zones.

25. Comparison of Structure of Early and Late Succession
Immature Ecosystem
Small plant size
Low species diversity
Mostly producers, few decomposers
Few ecological niches (generalized)
Low community organization
Mature Ecosystem
Large plant size
High species diversity
Mixture of producers, consumers and decomposers
Many ecological niches (specialized)
High community organization

26. Comparison of Function of Early and Late Succession
Immature Ecosystem
Low biomass
High primary productivity
Simple food chains and webs (mostly plants herbivore with few decomposers
Low efficiency of nutrient recycling
Low efficiency of energy use
Mature Ecosystem
High biomass
Low primary productivity
Complex food chains and webs (dominated by decomposers)
High efficiency of nutrient recycling
High efficiency of energy use