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RELATIONSHIPS OF NITROGEN LOADINGS AND PHYSICAL CHARACTERISTICS WITH PLANT STRUCTURE IN NEW ENGLAND SALT MARSHES
Citation:
Wigand, C AND R A. McKinney. RELATIONSHIPS OF NITROGEN LOADINGS AND PHYSICAL CHARACTERISTICS WITH PLANT STRUCTURE IN NEW ENGLAND SALT MARSHES. Presented at Society of Wetlands Scientists Conference, New Orleans, LA, June 8-13, 2003.
Description:
Nitrogen enrichment is hypothesized to cause competitive displacement of dominant plants in New England salt marshes. In this Narragansett Bay, RI, field survey, we examined the vascular plant species richness and the extent, density, and height of Spartina species in ten marshes which had a wide range of nitrogen loadings. Plant species richness ranged from 3.8 ?1.0 to 12.5?1.9 among the sites. Average Spartina densities were: tall S. alterniflora, 550 ? 89 shoots m-2; short S. alterniflora, 1058?247 shoots m-2; and S. patens, 4638 ? 1370 shoots m-2. Average shoot heights were: tall S. alterniflora, 107 ? 6.1 cm; short S. alterniflora, 55 ? 3.8 cm; and S. patens, 44 ? 2.8 cm. Marsh elevation and area did not significantly correlate with plant structure. Flood tide height significantly and inversely correlated with S. patens plant structure, but did not significantly relate to S. alterniflora or plant species richness. Marsh width significantly and positively correlated with plant species richness and S. patens, and inversely correlated with tall S. alterniflora plant structure. Significant inverse relationships were observed for N-load, % residential development, and slope with S. patens, short S. alterniflora, and species richness, and significant positive relationships with tall S. alterniflora. The marsh slope was significantly correlated with N-load which made it difficult to determine to what extent anthropogenic stressors were contributing to the variation in the plant structure. It is likely that the varying plant structure in New England marshes is a response to a combination of natural factors and anthropogenic stressors.