An experiment to suggest a technique for rehabilitation of a hard-limestone quarry floor in northern England was carried into its seventh year (see also Dixon & Hambler, 1984). The stress-tolerant grass Festuca rubra var. fallax Hack, cultivar Cascade proved suitable as a primary colonist, especially when sown onto rubble treated with a powdery manure derived from sewage. The community so produced was composed mainly of F. rubra and mosses, their proportions varying reciprocally with time but remaining approximately stable in a series of summer estimates of percentage cover.

The dry-weight per unit area of this vegetation, and that of other experimental sets, did not increase between the third and sixth years of the experiment. The organic content of the developing soil, however, increased considerably. Trifolium repens, where sown with the grass, had no obvious ecological impact, although its improved performance on Rabbit ‘middens’ indicated the general nutrient deficiency of the site.

A net flow of immigrant flowering-plants into the experimental site slowed down by the seventh year. Limestone grassland species arrived but the most abundant species were ruderals. All of the potentially large ruderal species failed to attain their full competitive potential, as did F. rubra. The community dominated by F. rubra and mosses proved unfavourable for the establishment of both Poa annua and Epilobium angustifolium— the latter being regarded as a particularly undesirable weed in this context.

The concept of visual acceptability was applied as a measure of the success of each sowing/treatment combination; the most successful might be recommended for rehabilitation of a worked-out limestone quarry.