Topic 7- succession Flashcards
Ecosystems are dynamic, define dynamic
they are constantly changing
Ecosystems change from being very simple to being relatively complex, what is this known as?
Succession
What conditions change in succession?
the biotic conditions (i.e. the living factors) and the abiotic conditions (i.e. the non-living factors)
Define primary succession
the process that occurs when newly formed or newly exposed land (with no species present) is gradually colonised (inhabited) by an increasing number of species
Give some examples of how primary succession could occur
The magma from erupting volcanoes cools and often leads to the formation of new rock surfaces or even new rocky islands in the sea
Another way new land can be exposed is by sea-level dropping or the drying up of a lake, leaving areas of bare rock
What are the pioneer species?
The first species to colonise the new land
What is humus?
As these pioneer species die and decompose, the dead organic matter
What is the climax community?
The final community formed, containing all the different plant and animal species that have now colonised the new land
At each 1._____ (___ -____) in succession, there are certain 2.____ that gradually 3.___ the local 4.____ so that it becomes more 5.____ for other species (with different 6._____) that have not yet colonised the new land
Give an example of this
- Stage (pioneer species colonisation to climax community)
2.species
3.change
4.environment
5.suitable
6.adaptations
Example: The pioneer species changing the aibiotic conditions to make the enviroment less hostile for the next colonosing species
Often, these new colonising species then change the environment in such a way that it becomes less what for the previous species?
Less suitable
Describe and explain the process of sucession using the example of Lichens
1.Pioneer species= lichens, thye colonise bare rock
2.Lichens help to break down the surface of the rock
3.Fragmented rock + humus (left behind when lichens decompose) form basic soil- lichens have changed the local enviroment so it is more suitable for other species (such as moss)
4.Moss grows until small plants and grass can colonise new land
5. These species result in the formation of a thin soil layer that covers the newly formed rock surface completely
6.Lichens cannot grow on soil, they now disappear from the ecosystem- the new species that arrived after the lichens have changed the environment in a way that it becomes less suitable for the lichens
7.Soil deepens further and trees are able to grow, they may then out-compete other smaller plant species, which may no longer be able to grow beneath the trees due to a lack of light
8.Process results in a change in biodiverity
What can interupt/ prevent the process if sucession?
What does this result in?
-Human activities
-Stops a climax communtiy from devolping
Define conservation
the protection and management of ecosystems
Why is conservation (to stop climax communities from devolping) sometimes a good thing?
-Ecosystems at the intermediate stages of succession (where small plants, grasses, ferns or shrubs are present) hold a distinct diversity of plant species that would no longer exist if the climax community was reached
Why is ity important to have a diverse range of plant species?
-They provide food and habitat for a high diversity of animal species (some of which may also be of conservation importance e.g. species that are rare or threatened, or species that have important ecosystem functions, such as pollinators like bees, which are also of great importance to humans due to their role in pollinating the crops we consume)
Can some conservation projects require the deliberate, artificial prevention of succession in order to preserve an ecosystem in its current stage of succession?
Yes
Explain what would happen if (in certain cases) conservation doesnt occur
-The area provide habitats for many species of plants and animals
-If succession occured the area (which is valuable) would be replaced by a climax communitydominanted by one species which cannot support the same species
-Species (which are important to the ecosystem) would be lost)
-By conserving the area it remains intact so ecosystems can be mainted, allowing for a higher overall species diversity
Give 2 ways that succession can be deliberately prevented for conservation purposes
1.Using grazing animals temporarily-they eat the growing shoots of shrubs and trees, this stops these plants from establishing themselves and prevents succession
2.Managed burning- controlled fires are deliberately lit and allowed to burn away the shrubs and trees, key species grow back quickly in their place- this resets the process of succession, meaning the larger, woody plants will take a long time to grow back (at which point the burning can be repeated)
