Psammosere
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In geography, a psammosere is a sand sere -an environment of sand substratum on which ecological succession occurs. Most common psammoseres are sand dune systems. In a typical succession on a sea-coast psammosere, the organisms closest to the sea will be salt tolerant species such as littoral algae and glasswort. Progessing inland the succession is likely to include meadow grass, sea purslane,and sea lavender eventually grading into a typical non-maritime terrestrial eco-system. Psammosere's graduate until they reach a climatic climax which ultimately leads to the growth of oak trees. As you move away from the high water mark there are many characteristic features that change and help you determine the natural succession of the dunes. For instance, the saturation rate slows down as you move inland from the HWM as the land is more compact and has better soils rather than sand which is seen at the start of the dune formation. The land is less acidic with closeness to the climatic climax as there are fewer shell pieces in the soil. The shell pieces are slightly acidic and prevent any substantial vegetation growth. As the quality of the soil improves and it has a more neutral pH it provides the foundation for increased growth and instead of basic marram grasses and heather there are ample conditions for such trees as birch and ash to survive.
Towards the beginning of the sand dune you should find the ph of the soil is infact akaline/neutral with a ph of 7.0/8.0 and I do believe the reason for this is that the shells make it alkaline, not acidic. As you follow along the dunes towards the grey slacks a podsol develops with a ph of 5.0/ 4.0 which is acidic before developing into mature podsols at the climatic climax with a ph of 3.5 - 4.5. This was taken from a coastal idealised psammosere model. (But put into my own words to avoid copyright)
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