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Vegetation succession: Sand Dunes 2b Difficulties which face pioneering plants; they usually formed nearest the sea and hence are liable to shift. Strong stormy high tides and people destroy plants and dunes. There is often hostile conditions with limited humus and nutrients. Water shortages as water drains easily through sand. Salty conditions form from the sea spray, and alkaline conditions because of shell fragments. C Three plants which colonise the foreshore are: sea rocket, sea lyme and couch grass. These plants can adapt to the conditions by being resistant to immersion in sea water during high tides. As they grow vertically and laterally, they bind the sand together and build up the dunes. They can do this by foliage trapping sand and roots binding.
The height of the plant reduces wind speed in the dune and allows it to expand shorewards. Grows over 1 meter in height Rhizomes, creep along underground allowing stems to spread rapidly . This allows plant to keep pace with new sand deposits.
Vegetation succession: Sand Dunes e On grey dunes the slacks, which are found further inshore, perennials grow, which increase the stability of the dune. Grey dunes have increased humus content which makes it look grey and this is enhanced by the surface being covered in lichens. As sand is no longer deposited here marran grass is replaced by creeping fescue, sand sedge, buttercups, dandelions. In the slacks water tolerant plants are found because the water table is closer to the surface. E.g. rushes, willows and alders.
Vegetation succession: Sand Dunes (f) Climax vegetation at Tentsmuir takes the form of a plagioclimax because of the heath land, and the arresting factor being the grazing of highland cattle. (g) See note on printed sheet.
Vegetation succession: Sand Dunes (h) The plants which are closest to the drift line at 12m are sea rocket and saltwort, these are the plants which colonise the embryo dune which is found directly behind the drift line. These plants are drought resistant (xerophytes). They are resistant to immersion by sea water, and their foliage traps sand. They bind the sand together allowing the embryo dune to stabilise. At 14-90m is the fore dune and yellow dune which is covered in marram grass, saltwort, couch grass, orache and lyme grass. These are pioneering plants and they do well in the drier mobile sand dunes. The marram grass has rhizomes, long creeping underground stems, which spread vertically and laterally and efficiently keep pace with fresh deposits of sand. Growing at a pace of at least one meter per year. The height of the marran grass also allows it to act as a wind break, and allows the dunes to grow inland. Beyond the mobile dunes are the fixed dunes (grey dunes) found at 100m+ behind the drift line. Plants growing here include; Ragwort, Rosebury, willow herb, buttercups and sea holly. These dunes are on the shore side and are more sheltered, conditions are now suited to a greater variety of plants as PH is now reduced and more acidic, and humus content greater. Sand no longer accumulates, and marram grass is out competed by new colonising plants. At 180 m climax vegetation is reached, a woodland made up of Scot spine, this happens because of increased organic content of the soil, making it nutrient rich and being sheltered from the wind.
