Survivorship and spatial development of Spartina alterniflora loisel. (Gramineae) seedlings in a New England salt marsh

Abstract

Patterns of survival and spatial arrangement of tillers of Spartina alterniflora were examined in natural and in artificially produced bare areas, and in pure stands of adult S. alterniflora in a New England salt marsh. Seedling growth and survival were high in naturally occurring bare patches and in artificial patches, whether created by continual clipping of adult plants to ground level throughout the growing season or by providing bare substrate after removal of adult plants. Seedling growth and survivorship increased with increasing size of bare area. S. alterniflora seedlings were also common in areas dominated by adult plants, but no seedlings survived a whole first growing season under the mature canopy, probably because of competition from adult plants.In large bare areas, S. alterniflora seedlings grew non-directionally, reaching heights of 0.5 m, and producing as many as 36 tillers in one growing season. Examination of leaf area ratios suggested that the production of tillers increased photosynthetic capacity in seedlings with several tillers in contrast to seedlings without tillers. Thus, seedlings can apparently tiller and colonize free space radially without a loss of photosynthetic capacity.These results suggest that while seedling success is generally limited by adult plants in monocultures of S. alterniflora, in disturbed spaces seedling success is high and results in a rapid non-directional proliferation of sexually generated clones that ultimately preclude the successful invasion of future seedlings. © 1986 Annals of Botany Company.