The Vegetation of the Sand Dunes of the Camel Estuary, North Cornwall

Abstract

A considerable number of papers have already appeared, describing the vegetation occurring on sand dunes in the British Isles, and the pioneer stages in the colonization of mobile dunes seem to conform generally to a well-marked type. When, however, the sand has become partially fixed, a large number of non-maritime species are able to gain a foothold, and in this stage the composition of the vegetation as it passes into 'fixed dune' shows a great variety in the areas which have been studied. The species occurring must clearly depend to a large extent on the proximity of seed parents and also on the power of a particular species to survive in sand which is still partially mobile. The ultimate vegetation must also be influenced by the nature of the sand. The front dunes in all areas which have been studied seem to be generally alkaline, largely as a result of their salt content. Where the sand contains little CaCO3, however, the older dunes tend to become acid and the subsequent vegetation is accordingly influenced. The chief interest in the present study lies in the fact that the sand, even in the oldest and most fixed portions of the area, is always highly calcareous and contains at least 50% CaCO3, with a pH exceeding 8-0. The other feature of interest about these Cornish dunes is that they include a well-defined area of dunes which have recently been formed and whose age is known with some accuracy. These dunes show the early stages of colonization very clearly. It will be seen from the lists of species included in this paper that this area is no exception in supporting a very varied flora, including some species which do not seem to have been recorded from similar habitats elsewhere. An analysis of the vegetation occurring on more or less fixed dunes in a number of localities in the British Isles and Ireland has been included at the end of this paper. This list, besides showing something of the great variety of the flora, shows that a number of non-maritime species occur in this type of habitat with considerable regularity. It had been hoped to include in this paper studies of the more extensive sand-dune areas along the north Cornish coast, at Perranporth and elsewhere, but transport difficulties have unfortunately made this impossible. The area studied is situated on the east side of the Camel estuary on the coast of north Cornwall, opposite the little port of Padstow (see Fig. 1). The front of the dunes extends from a point just south of Brea Hill to the village of Rock, a distance of about 2Ikm. Behind this is a large area of fixed dune and blown sand, which extends in some places for a distance of over I km. from the water's edge and reaches as far north as Daymer Bay. The blown sand covers, usually thickly, an area of slate or diabase, and much of it lies over 30 m. above the sea. The vegetation of the whole blown-sand area is very similar to that on the lower lying fixed dunes nearer the sea, which were more intensively studied for the detailed lists in this paper. Much of the blown-sand area is occupied by the St Enodoc Golf Course, with the result that the vegetation on the fairways and greens has been considerably modified.