1. Succession and Zonation
What is the difference?
Succession: How an ecosystem changes in time
Zonation: How an ecosystem in changing in space (along an environmental gradient like altitude)

2. Zonation
Every niche has limits, outside of which, the species cannot survive
The most important factors that influence these limits (Limiting Factors)
Temperature
Precipitation
Solar Insolation
Soil Type
Species Interactions
Human Activities
Alter zonation through
road building etc.
Kite Diagram

3. Succession Succession Primary Succession Secondary Succession
Bare land doesn’t stay bare for long
The change is directional resulting in a natural increase in complexity
Primary Succession
Occurs on a bare inorganic surface
Occurs when new land is created or uncovered
Volcanoes
River Deltas
Sand Dunes
Glacial Retreat
Secondary Succession
When an already established community is suddenly destroyed
Fire
Flood
Humans (agriculture)
Occurs on soils that are already developed
Results in a quicker version of succession

4. Succession Changes During Succession Primary Succession
Secondary Succession
Changes During Succession
Size of organisms increases
Simple food chains become complex food webs
Soil depth/quality increases
Biodiversity increases as niche structure develops
NPP and GPP rise and then fall

5. Productivity Changes in Succession
Primary Productivity (Varies with time)
Low at first (few plants)
Rises throughout intermediate stages
Levels off during climax stages because respiration rates are starting to equal the rate at which energy is fixed by producers
Early Stages
Gross productivity is low…but
Respiration rates are low too so net productivity is high
***The system is growing***
Later Stages
P:R ratio approaches 1

6. K and R Strategists K-Strategist r-Strategist
K is carrying capacity
r-Strategist
r is biotic potential (exponential)
Many species show a mixture

7. Survivorship Curves Type 1 (Late Loss) Type II (Constant Loss)
Typical for K-selected species
Most likely to die later in life
Type II (Constant Loss)
Relatively rare
Equal chance of dying at any time
Types III (Early Loss)
Typical for r-selected species
Most mortality occurs in early life stages