Vegetation Succession in sand dunes at Murlough Reserve- AS Geography

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Using a case study of a vegetation succession that you have studied, describe and explain the changes that occur from the pioneer species to climatic climax vegetation.

My chosen succession is a psammosere (sand dune succession). The sand dune system is located in Murlough Reserve, near Newcastle in County Down. The sand dune system is over 5000 years old, containing part of the remaining 20% of sand dune systems left in Northern Ireland.

To begin with, we may start at seral stage one, known more familiarly as the ‘embryo dune’. Here the pioneer species, sea couch grass being a prime example, can withstand harsh environments, although many cannot which is why there is only 4 species at this stage. The salt spray in particular prevents a number of species from growing; it is because these plants are halophytic (salt tolerant) that they are able to survive. In addition to the salt and winds, the organic content is low, at around 0.5%. The ground cover is only 5% and many of the plants grow individually. The PH is around 8, which is slightly alkaline.

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At seral stage two, there are a number of differences which increase the level of biotic and abiotic components. At this ‘foredune’, Marram grass dominates. The grass thrives on being buried in sand, and its rhizome root networks help stabilise the dune. The pioneer plants increase the organic content in the soil as they decompose releasing vital nutrients. The organic content is around 1.1%, which is an increase of 0.6% from seral stage one. The PH here becomes gradually more neutral, which is much more suitable for plants to grow. Due to this the number of species increases to 6, ...

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