Emergence, survival and initial growth of North American prairie forbs and British meadow forbs and grasses in low-productivity urban "waste" soils

Twenty-two species of North American and British forbs naturally associated with dry, unproductive habitats were sown as mono-cultures into pots containing mixes of brick rubble, sand and sub-soil. Three grass species native to Britain were also included as a contrast. Individual species exhibited considerable variation in emergence characteristics; both temporally, and as a percentage of seed sown. Geographical origin had no marked effect on emergence characteristics, although it appears that American species are more sensitive to moisture stress at germination. Grasses demonstrated significantly greater survival than either British or North American forbs at the group level of comparison and produced the highest biomass in the first growing season. North American forbs did not differ significantly from British forbs in terms of weight of first year growth. Overall, brick rubble proved to be the least satisfactory substrate in terms of emergence, survival and initial growth. Sand and sand:subsoil mixes supported high seedling emergence, survival and satisfactory first year growth. The results are discussed in relation to the physical and chemical properties of the four substrates, and an assessment is made of the implications of the study for future work.