7. Ecological Succession

7.1 Succession

Starter Match up the key

word to the definition

Ecosystem

Biotic

Abiotic

Community

An ecological factor that makes up part of the non-biological

environment

More or less self-contained functional unit in ecology made up

of all the interacting biotic and abiotic factors in an area

The organisms of all species that live in the same area

An ecological factor that makes up part of the living environment

of an organism

Learning Objectives

Describe changes that occur in the variety of species occupying an area over time

Define succession and climax communitySuccess Criteria You can describe the order of plant

succession and explain common features of succession

Succession

The changes, over time, in the species that occupy a particular area

Succession of bare rock or barren land Succession happens when an area is first

colonised. What might happen to cause this?A retreating glacier depositing rockWind or sea piling sand into dunesVolcanoes erupting and depositing lavaLand subsiding and creating lakes or pondsSilt and mud being deposited at river

estuaries

Pioneer Species

The first stage of succession involves pioneer species colonising an inhospitable environment

Pioneer species have features that suit them to colonisation

Task

In pairs, come up with a list of features that pioneer species may have, which would help them to colonise inhospitable environments

Features of Pioneer Species

Production of a lot of wind-dispersed seeds to easily reach isolated areas

Rapid germination of seeds The ability to photosynthesise The ability to fix nitrogen from the

atmosphere Tolerance to extreme conditions

Stages of Plant Succession

Stages of Plant Succession

Colonisers (lichens): when they die, they release nutrients. This changes the abiotic environment by creating soil.

Mosses, then Ferns: rock is continually eroded, as these die organic matter increases, building up soil

Small flowering plants, shrubs then trees establish

Climax Community

The organisms that make up the final stage of ecological succession

A balanced equilibrium In the UK, this is deciduous woodland

Animal Succession

Animal species present depend on the plant species found in the area

For example, mosses and grasses provide food and habitats for insects and worms. These can then support secondary consumers.

Common features in any succession The non-living environment becomes less

hostile A greater number and variety of habitats Increased biodiversity More complex food webs Increased biomass

Land alteration Succession also occurs when land is

suddenly altered e.g. from a fire The area will then undergo succession to

return to a stable, climax community This type of succession doesn’t begin with

a pioneer species

Learning Objectives

Describe changes that occur in the variety of species occupying an area over time

Define succession and climax communitySuccess Criteria You can describe the order of plant

succession and explain common features of succession