Effects of substrate composition on the establishment of seedlings during restoration of a coastal shingle plant community, Suffolk, England

  • Published source details Walmsley C.A. & Davy A.J. (1997) The restoration of coastal shingle vegetation: effects of substrate composition on the establishment of seedlings. Journal of Applied Ecology, 34, 143-153


Shingle beach vegetation at Sizewell, Suffolk, eastern England, was extensively damaged during construction of a power station. The feasibility of restoring the vegetation by directly sowing seeds of five species important in the existing plant communities, in field and glasshouse experiments was investigated. Summarised here are the results of the field trials.

Study site: The experiment examining the effects of substrate composition and effects of position relative to the sea on the establishment of seedlings was undertaken on the c. 50 m wide beach at Sizewell, eastern England (National Grid ref: TM 475635). Vegetation on this predominantly shingle beach (with some sandier areas) is dominated by a few clonal perennials e.g. sea sandwort Honckenya peploides, sea pea Lathyrus japonicus and marram grass Ammophila arenaria.

Experimental design: The field experiment examined the effects of proximity to the sea, composition of the beach substrate, and its amendment with organic matter on seedling emergence and establishment. Between 7 to 12 May 1991, on a sparsely vegetated, 15 x 15 m beach section from the strandline to the upper beach edge, a matrix of 1 x 5 m plots (separated by 0.5 or 1 m paths) parallel to the shoreline, was established. Each row and column contained: four untreated/unsown (control) plots (raked level, no other treatment); two untreated/sown plots; two organic matter treated/sown plots.

Seeded plots were sown by broadcasting and seed raked in. Organic matter plots received 50L of composted bark raked into the top 10 cm of shingle prior to seed sowing.

Seed preparation and sowing: In May 1991, species sown in a mix of unprepared seed were: sea kale Crambe maritima, sea holly Eryngium maritimum, yellow horned-poppy Glaucium flavum, sea pea Lathyrus japonicus and curled dock Rumex crispus ssp. littoreus. The seed was collected at Sizewell in 1986, stored, and at time of sowing were about 4.5 years old. Germination tests carried out prior to sowing resulted in the following percentage seed germination rates:

Crambe maritima - 59%

Eryngium maritimum - 22%

Glaucium flavum - 88%

Lathyrus japonicus - 91%

Rumex crispus - 100%

Topography and substrate: The site was surveyed on 7 May 1991 and 11-15 October 1993 to obtain topographic measurements of the beach profile. Substrate cores (10 cm diameter, 13 cm deep) were taken prior to sowing and particle size analysed by sieving and weighing.

Seedling emergence was recorded at 2-monthly intervals between February 1992 and February 1993. The few 1991 plants were visibly different from those emerging later, and were tagged as required for identification purposes. The reproductive capacity of G.flavum (which had the greatest emergence of the five species), was also estimated by recording the maximum reproductive stem height and number of pods per plant, and seedling growth was monitored.

Plant emergence: There was little emergence of seedlings during the first season (a few G.flavum and R.crispus seedlings only) and most occurred in the following spring, between February and April. A low percentage of the viable seeds of all five species had emerged even after two seasons (see below). Greatest emergence was of G.flavum (34% overall, rising to 62% in sandier plots), whereas the relatively long-lived perennials showed lower emergence (1.3-18%) and slower growth. Only G.flavum produced reproductive plants, in the second year.

Total emergence of viable seed sown for each of the five species was:

Crambe maritima - 18%

Eryngium maritimum - 4.7%

Glaucium flavum - 34%

Lathyrus japonicus - 1.3%

Rumex crispus - 9.5%

Effects of substrate: Seedling emergence was greater in organic matter treated plots for all species and most emerged better from sandy plots than shingle dominated plots. Although G.flavum emergence was greater in sandy plots (62%), seedling survivorship and growth were much greater in shingle plots.

Conclusions: Direct sowing of seeds on the beach at Sizewell resulted in poor overall establishment of the five species sown. This method therefore is not recommended as a general technique for the restoration of shingle beach vegetation, except for annual or monocarpic species (e.g. G.flavum). Amendment with organic matter provided little benefit that could not have been achieved more simply by the addition of beach sand to the coarsest shingle substrates.

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