GERMINATION CHARACTERISTICS OF SHINGLE BEACH SPECIES, EFFECTS OF SEEDAGING AND THEIR IMPLICATIONS FOR VEGETATION RESTORATION

1. Restoration of coastal-shingle vegetation at Sizewell, Suffolk, UK, after construction of a power station, was underpinned by an investig ation into the germination ecology of six key species: Crambe maritima , Eryngium maritimum, Glaucium flavum, Honckenya peploides, Lathyrus j aponicus and Rumex crispus. The use of indigenous seed, collected from the site before the 6-year construction project, necessitated long-te rm storage. The effects of seed ageing on viability and germination re sponses to temperature, light and salinity were examined to determine how any reduction in germination might be mitigated. 2. Innate seed do rmancy was important in all species, except R. crispus. C. maritima an d L. japonicus showed hard-seed dormancy. Stratification of E. maritim um, G. flavum and H. peploides effectively softened the pericarp or te sta, and satisfied their varying requirements for low temperature to o vercome physiological dormancy. 3. All species germinated well in diur nally alternating temperature regimes. Germination of H. peploides was promoted by light, but the other species were insensitive to light. I ncreasing salinity progressively reduced germination rate relative to that in distilled water, and sea water at concentrations of 50% or mor e completely inhibited germination. 4. Seed storage at low temperature and humidity for 7 years did not affect innate dormancy, except in H. peploides, where the requirement for stratification was lost. Storage reduced germination rate in all species, except R. crispus. Ageing re sulted in considerably less germination at higher temperatures in some species. Salinity-enforced dormancy was significantly greater in aged seed for four of the species. The promotion of germination by light i n H. peploides disappeared with age. These changes represented a narro wing of the environmental conditions that allow germination, even when viability only declined slightly. 5. Innate dormancy among shingle sp ecies and the use of stored seed, with high viability, but stringent g ermination requirements, are likely to result in poor and erratic germ ination. The use of appropriate pretreatments to overcome dormancy and optimal conditions for germination should allow the efficient use of seed for plant production in restoration projects.