A Floristic Survey and Comparison of Marsh Vegetation Ranging From Non-Tidal Freshwater To Ocean Salinities Along the Elbe (Germany) and Connecticut (Northeastern USA) Rivers

Abstract

Abstract Relationships between the flora and vegetation of northern Europe and the northeastern United States have been long noted but little studied. Here, quantitative sampling of high, low, and mid-marsh zones was carried out in 20 marshes along a gradient from non-tidal freshwater via tidal freshwater and brackish to salt marshes in each of two large river systems, the Elbe in Europe (Germany) and the Connecticut in North America (southern New England, USA). The composition of each zone of each marsh type in the two river systems is described. The marsh floras are compared, and possible reasons for differences in vegetation composition, non-native species occurrences, species richness patterns, and the origin of marsh floras are discussed. Twenty-two species occurred in both river systems, nearly 10% of the total marsh flora. Shared species were found in all four marsh types and occasionally in more than one marsh type. Introduced taxa are not prominent in either river system except for Spartina angli...