Coastal sand dunes as biological systems

Abstract

SynopsisWith the gradation of intensities of environmental factors from the strand-line to stable inland areas, coastal dunes show many ecological phenomena especially clearly. These are reviewed broadly, with some emphasis on topics on which important advances are being made. The nutrient status of dune soil and changes with time are shown with reference to several dune systems. Changes in major nutrients are given for Braunton Burrows, north Devon, where the influence of nitrogen fixation by Lotus corniculatus is illustrated. The effects of sand burial on plants are considered, and details given of the root systems of vigorous and relict marram; factors which may affect its decline in vigour are reviewed. Also discussed is the likely significance of nematodes in the decline of Hippophaë rhamnoides. Reasons for the richness of the dune flora are considered and also some autecological studies. At the physiological level, reference is made to the water relations of plants and at the biochemical level to the occurrence and possible ecological importance of stress metabolites. Life strategies, phenology, survivorship, competition and the population ecology of dune plants are reviewed and also the interaction of ragwort (Senecio jacobaea) and cinnabar moth (Tyria jacobaeae). The population genetics of dune plants is illustrated by reference to Festuca rubra and Ammophila arenaria and of animals to Cepaea nemoralis.The abundance and ecological relationships of the invertebrate fauna are exemplified by surveys at Spurn Point, extensive investigations on spiders and the influence of marram on arthropod communities. The ecology of the natterjack load is considered in relation to conservation and the effects of large animal grazers in relation to the diversity of vegetation.