Vascular plants of a Delaware River tidal freshwater wetland and adjacent terrestrial areas: Seed bank and vegetation comparisons of reference and constructed marshes and annotated species list

摘要

Constructed wetland soil samples contained many more species with densities > 100 seeds/m(2) than reference marsh ones (102 vs. 28); constructed wetland densities for many species were considerably higher and richness (species/sample) were > 2X greater than the reference marsh. Of the total 218 seed bank species, 60 were common to both and 34 occurred only in reference marsh samples. Numbers of cover species were similar, but composition differed. Invasive species, notably Lythrum salicaria, Phalaris arundinacea, and Phragmites australis, were more important in constructed wetland soil samples and vegetation. Non-native species comprised 9 % and 13 % of the reference marsh and constructed wetland seed bank species and 8 % and 12 % of the cover species, respectively. Variable dispersal patterns and in situ seed production contributed to these differences. Over the entire study area (wetlands and adjacent terrestrial areas) we recorded 875 species, representing 141 families, more than doubling the number observed in a 1988 report. The families having the most species were Asteraceae (103 species), Poaceae (100), and Cyperaceae (83). The largest genera were Carex (46) and Polygonum (19); seven other genera also had ! 10 species. Nine species were pseudo-viviparous, producing plantlets on inflorescences. Non-native species comprised 27 % of the total flora. Overall there were 37 NJ rare/endangered species for the entire area; 11 occurred only in the constructed wetland with constructed wetland soil samples containing more than the reference marsh samples (8 vs. 1). Available lists from 1824, 1887, and 1964/65 and five species known only from herbarium specimens indicate that several species have been extirpated since the 19(th) C. Anthropogenic influences continue to have impact on diversity.