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The effects of human activity on succession illustrated by one
plagioclimax: heather moorland:
Succession can be prevented from reaching the climatic climax or encouraged
towards different climax as a result of human interference. The resulting
ecosystem is known as a plagioclimax stable plant community that has
arisen as a result of human intervention on natural succession.
E.g. heather moorland. Most prominent in areas such as North York Moors.
There is less than 10% of original woodland remaining in England and wales,
the rest is plagioclimax. British Isles has the highest density of heather
moorland globally (75%, mainly upland areas)
After the last ice age (200,000 years ago) climatic vegetation of deciduous
woodland (e.g. scot pine and birch) were dominant and it covered much of
the upland areas. However, from the AngloSaxon age (11th
little woodland remained as it was cleared for agriculture. As a result there
was poor soil quality so only hardy plants able to survive in low fertility were
able to survive. Lacked deep roots were able to supply nutrients to surface
soil and rainfall once intercepted by trees was now able to leach nutrients so
therefore uplands were often colonised by heather (dominant), bracken and
grasses. Human interference prevented succession as the climatic climax was
The regeneration of climax vegetation has been largely prevented due to
grazing of sheep. It became main form of agriculture because it was difficult
to utilise the land. This destroys young saplings therefore preventing further
seral succession towards climax woodland. Heather moorland is now
managed by other strategies mainly to support wildlife.
Much of management is through private ownership as there is income
generated from shooting on grouse moors which are situated on heather
Managed burning: encourages development of new heather shoots and
causes less fire resistant species to be destroyed resulting in dominance of
heather. Aim is to conserve as much of valuable nutrients as possible
therefore it is burnt roughly every 12 15 years. If left any longer it would
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It helps to create heather of different ages. There are four growth stages.
2) Building stage shoots (up to 15 years)
3) Mature stage heather dominance but becoming woody (up to 25
4) Degenerate (up to 30 years) grasses, degenerating heather.
Older woody heather = nesting cover and newer shoots = food for wildlife
e.g. red grouse.…read more