The fixed dunes were once mobile dunes, like those nearer the sea. Over time, new dunes have formed to seaward and interrupted the supply of fresh sand. The once dominant Marram grass and Lyme grass have been replaced by new plant communities and thin, impoverished soils have developed on what was raw sand.
The fixed dune grassland is dominated by Red Fescue Grass and the spikes of small, yellow flowers of Lady's Bedstraw. A wide range of flowering plants including Restharrow, Bird's foot Trefoil and various types of vetches and clovers provide food for may different moths and butterflies. Particularly apparent during the summer months are Common Blue and Meadow Brown butterflies together with Cinnabar and Six-spot Burnet moths. Many animals can be found here, including invertebrates like the Banded Snail.
The fixed dune grassland is rich in low-growing herbaceous plants and grassed because the low levels of nutrients in the soil prevent may other more aggressive species from growing. The grassland was, in the past, maintained by the grazing of cattle and sheep. This system of management lapsed early in this century and since then no agricultural activity has taken place on the dunes. The absence of grazing has encouraged the development of scrub, except where rabbit grazing is occurring. Rabbits are now the only large grazing animals on the reserve and are vital to the survival of the grassland areas.
One of the major aims of the management of the Reserve is to preserve the species diversity within the dune grassland, which has been threatened by the increasing amount of nutrients (especially nitrates) in the soil. the nitrates come from plants like vetches, clovers and Sea Buckthorn which are able to convert atmospheric nitrogen into the soil and taller, more aggressive plants begin to grow. This process is being reversed by regular cutting back, clearing and treating the invasive vegetation. Also, the existing grassland is mowed after the plants have flowered and set seed.
The scrub which surrounds the grassland is mainly composed of Sea Buckthorn, with patches of Sallow, Elder and Hawthorn. These bushes offer cover for a variety of birds, including the Blackcap. Cuckoos may be seen in the summer. The female Cuckoo lays her eggs in the nests of many different species, including warblers and pipits.
During the last hundred years or so, a number of alien species have been introduced to the area. The most obvious of these are the Evening Primroses, whose large yellow flowers open at night, providing nectar for visiting moths.