Download - Biology - Colonisation and Succession
CHAPTER 8:
DYNAMIC ECOSYSTEM
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8.2 COLONISATION AND SUCCESSION IN AN ECOSYSTEM
Ecosystem
Dynamic Ecosystem
Habitat
A community of organisms which interact with their non-living environment and function as a unit
Biotic components are well balanced with one another and with the abiotic components
- Natural environment where organisms live-Provides basic resources og life such as food, shelter, living space, nesting sites and mates
Species
Ecosystem
community Population
Species
A group of organisms that: look alike and have similar characteristics share the same roles in an ecosystem capable of interbreeding to produce fertile offspring
population
A group of organisms of the same species living in the same habitat at the same time
- A several populations of different species living in the same habitat of an ecosystem-Interpendent and interact with one another in order to survive
Community
NICHE-A niche of an organism is its role in the ecosystem-Niche of a population:
ranges of temperatures at which it lives the type of food it eats the space it occupies
-animals that undergo metamorphosis in their cycle occupy different niches.
A tadpole lives entirely in water
A frog lives mainly on the land
Climax community
(trees )
COLONISATION
Dominant species
(shrubs )
Successor species
(herbaceous plant )
Pioneer species ( grasses )
Bare ground
BARE GROUND
• An environment of bare rocks and sand left behind by a forest fire is not suitable for most organisms.
• After the ground cools down, water re-enters the environment. When water, air, nutrients and sunlight are available, spores and seeds of certain plants start to germinate and grow.
PIONEER SPECIES
• The first colonizers• Special adaptations is enable to survive on dry
and nutrient-poor soil• Hardy plants which usually have dense root
system to bind the sand particles and hold water and humus
• Short life cycle• When die, they remains add to the humus
content of soil
Successor species
• Modify the environment, eventually creating conditions which are less favorable to themselves
• Grow bigger than pioneer species, thus reducing the amount of sunlight that reaches them and gradually replacing them
• Have small wind-dispensable seeds which are able to spread and grow rapidly
• Change the structure and quality of the soil, making it more conductive for larger plants to grow
Dominant species
• Can grow faster and so they out-compete the pioneers which grow at a slower rate
• Turn modify the environment which allows larger trees to grow
• The larger trees out-compete the shrubs, which are replaced by forest-floor species which require low light intensit
(succession)
Climax community
• Ecological success leads to a relatively stable community which is in equilibrium with its environment
• Example: tropical rainforest in Malaysia• A stable community that undergoes little or no
change in its species composition
Colonisation
• A process whereby a species invades and occupies a newly formed area where no life has existed previously
Succession
• The gradual process through which one community changes its environment so that it is replaced by another community