The restoration of coastal shingle vegetation: effects of substrate composition on the establishment of container-grown plants.
The use of container-grown plants in restoring shingle beach vegetation was investigated at Sizewell, Suffolk, UK, where the vegetation had been destroyed by the construction of a power station. Six species, Crambe maritima, Eryngium maritimum, Glaucium flavum, Honckenya peploides, Lathyrus japonicus and Rumex crispus, were selected to counter erosion and assist the development of a more complex and natural community. Plants were raised from stored seed, indigenous to the site, by horticultural techniques. Shingle substrates are dry, nutrient-poor and heterogeneous in their physical composition. Field experiments investigated the efficacy of organic matter and fertilizer treatments as ameliorants, and examined the influence of position on the beach profile and substrate composition on the establishment of container-grown plants. Neither organic matter nor fertilizer additions had any significant effect on mean plant size in any species after one field season. Planting location on the beach profile was the most important factor influencing establishment. Crambe maritima, G. flavum, H. peploides and R. crispus plants all grew significantly larger in the seaward plots, with more coarse shingle. Only G. flavum produced many reproductive plants during the first year, and these were more frequent and more fecund in the seaward plots. The establishment of container-grown plants of four of the species was also compared at two sites at similar distances from the sea, but with sandy or shingle-dominated substrates, respectively. Again, greater growth on the coarser shingle substrate by three of the most characteristic shingle beach species reflected an apparent selective advantage. Thus, substrate physical composition was probably the primary determinant of differences in performance across the beach profile. The use of container-grown plants to establish shingle vegetation resulted in low mortality, with rapid plant growth and establishment. Fertilizer and organic matter treatments were not generally cost-effective in establishing shingle beach vegetation from container-grown plants. The use of resources to recreate an appropriate substrate composition is of far greater importance.