Colonisation & Succession

COLONISATION & SUCCESSION

COLONISATION takes place in newly formed areas  Example: an environment of sand and stones  The first colonisers are called pioneer species. 

PIONEER SPECIES      

Have special adaptations Can survive on dry and nutrient poor soil Usually are hardy plants which have dense root systems to bind sand particles, water and humus Short life cycle When they die, their remains add to the humus content of the soil Pioneer species establish conditions that are more conducive to other species that is called successor species.

SUCCESSOR SPECIES  Grow

bigger than the pioneer species  Most of these plants have small winddispersable seeds (enable them to spread and grow rapidly  The successor species also change the structure and quality of soil, making it more conducive for larger plants to grow  The plants that grow over the remaining of successor species are called dominant species.

DOMINANT SPECIES  Can

grow faster and can out-compete the pioneers which grow at a slower rate  As time passes, the dominant species modify the environment which allows larger trees to grow  Gradual process through which one community changes its environment so that it is replaced by another community is called succession.

CLIMAX COMMUNITY  Ecological

succession leads to a relative stable community which is equilibrium with its environment.  The stable community is called a climax community.  A climax community is a stable community that undergoes little or no change in its species composition.

 Example

of pioneer species: lalang,

grass  Successor species: Herbaceous  Dominant species: Shrubs  Climax community: Rainforest

COLONISATION & SUCCESSION IN MANGROVE SWAMPS  Pioneer

species: Avicennia sp and Sonneratia sp  Characteristics: long underground cable roots that support them in soft and muddy soil  The roots also produce hundreds of thin, vertical breathing roots called pneumatophores

Pneumatophores

COLONISATION & SUCCESSION IN MANGROVE SWAMPS  Successor

species: Rhizophora sp.  Has prop roots  These aerial roots anchor plants to the mud and play important role in aeration  Aeration can also take place through lenticels on the tree bark.

Prop Roots

COLONISATION & SUCCESSION IN MANGROVE SWAMPS  Dominant

species: Bruguiera sp.  Has buttress root forms loop that protrude from soil to trap more silt and mud.  This modifies the soil structure gradually.  Over time, terrestrial plants such as Nypa sp., Pandanus sp., begin to replace the Bruguiera sp.