Editing Dune (section)

====Ecological succession on coastal dunes====
As a dune forms, plant [[Ecological succession|succession]] occurs. The conditions on an ''embryo dune'' are harsh, with [[salt spray]] from the sea carried on strong winds. The dune is well drained and often dry, and composed of calcium carbonate from seashells. Rotting [[seaweed]], brought in by storm waves adds nutrients to allow [[pioneer species]] to colonize the dune. For example, in the [[United Kingdom]] these pioneer species are often [[Ammophila (Poaceae)|marram grass]], [[sea wort grass]] and other sea grasses. These plants are well adapted to the harsh conditions of the foredune, typically having deep roots which reach the [[water table]], [[root nodules]] that produce [[nitrogen]] compounds, and protected [[stoma]], reducing [[transpiration]]. Also, the deep roots bind the sand together, and the dune grows into a [[foredune]] as more sand is blown over the grasses. The grasses add [[nitrogen]] to the soil, meaning other, less hardy plants can then colonize the dunes. Typically these are [[Calluna|heather]], [[Heath (habitat)|heath]]s and [[gorse]]s. These too are adapted to the low [[Soil#Soil moisture|soil water]] content and have small, prickly leaves which reduce transpiration. Heather adds [[humus]] to the soil and is usually replaced by [[conifer]]ous trees, which can tolerate low [[soil pH]], caused by the accumulation and decomposition of organic matter with nitrate leaching.<ref name=Miles1985>{{Cite journal| last = Miles | first = J.| year = 1985| title = The pedogenic effects of different species and vegetation types and the implications of succession| journal = European Journal of Soil Science| volume = 36| issue = 4| pages = 571–584| doi = 10.1111/j.1365-2389.1985.tb00359.x}}</ref> Coniferous forests and [[heathland]] are common [[climax community|climax communities]] for sand dune systems.

Young dunes are called [[yellow dune]]s and dunes which have high humus content are called [[grey dune]]s. Leaching occurs on the dunes, washing humus into the slacks, and the slacks may be much more developed than the exposed tops of the dunes. It is usually in the slacks that more rare species are developed and there is a tendency for the dune slacks' soil to be waterlogged where only marsh plants can survive. In Europe these plants include: creeping willow, cotton grass, [[yellow iris]], reeds, and rushes. As for vertebrates in European dunes, [[natterjack toad]]s sometimes breed here.