Change over time

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SUCCESSION is a series of changes that take place in a plant community over time

If undisturbed, succession will reach it's final stage called it's climatic climax: this is when the plant species are in perfect balance with the environmental conditions

Although, climate plays a major factor in influencing plant growth. However, on a local scale other factors such as:

-relief

-geology

-drainage

can affect plant growth (locally)

There are two basic types of succession

Primary succession

Secondary succesion

PRIMARY SUCCESSION

Occurs on surfaces where there had not been previous vegetation e.g. lava flows, bare rock and sand dunes

Two main types of primary succession:

Xerosere- formed on dry land, this can be subdivided into (1) lithoseres-bare rock (2) psammoseres- sand dunes

Hydrosere- formed in water, this can be subdivided into (1) haloseres-salthy water (2)hydroseres-fresh water

SECONDARY SUCCESSION

This occurs after an area of existing plant community has been modified due to human interference by deforestation or naturally by landslide or fire caused by lightning

Development of a succession

Lichens is a fungus that has algae living inside of it

It first attacks on the bare rock surface. These pioneer species are hardy plants as they are able to withstand such harsh conditions (adapted)

They do not require the need of soil as they are the main agents of creating the soil by breaking/attacking the rock

They compete for space, light, water and nutrients

Microclimate - the climate of a very small or restricted area, esp. when this differs from the climate of the surrounding area.

They can affect the microclimate of the conditions:

shelter, temperature, humidity

The roots of the pioneer plants help to break/weather the surface and so to aid soil formation

As it develops, it passes through a series of stages called seres

There is the creation of immature soil, and this enables other plants to colonise and change the existing balance of species

Each stage provides better conditions for plant growth than the previous one as the addition of organic matter (decaying vegetation) is added to the developing soil this helps to improve it's structure and water retention qualities

Example of a plant succession:

Lithosere

Starts on a newly exposed rock surface that has might've been created by an eruption of a volcano leaving a new,bare lava surface

Raised beach

Raised beach, the west coast of Scotland

caused by either:

(1) A fall in sea levels

(2) By the isostatic uplift of land form the sea

Initially colonised by bacteria and algae that can survive in such harsh conditions

Pioneers begin to colonise, lichens. They can withstand the acute water shortage and help to assist water retention

As water retention improves, moss begins to grow. This help to further improve water retention. Also weathers the rock to produce soil which encourage advanced plants to grow

Ferns, herbs appear. When they die, the bacteria recycles the nutrients by converting the remains to hummus which further improves soil fertility

Shrubs grow, shading grass and herbs

Pioneer trees are established. They are fast growing species (birch)

Slow growing tree species begin to develop such as ash and oak

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