Urban wetland seed bank profiles in south-central New York State1,2

Abstract

Wetlands are important habitats in urban landscapes that reduce flooding and improve water quality, yet urban wetland seed banks are rarely studied. Our main objective was to profile urban wetland seed banks in south-central New York. We exposed sediment cores from four wetlands in Broome County, New York, to flooded and drawdown treatments for 16 mo, and recorded community composition and seedling density. We found high spatial variation in species richness and seedling density among the four sites. Species richness ranged from 28 to 56 species, with sample-based extrapolation (Sest), Jackknife1, and Chao1 analyses estimating similar expected species richness values (Sest projected 37.9–77.0 species, Jackknife1 analysis estimated 40.5–77.8 species, and Chao1 projected 32.2–79.1 species). Mean seedling density ranged from 3,367 seedlings/m2 to 19,132 seedlings/m2. These seed banks were dominated by obligate wetland species (75.8–93.3%). Invasive species comprised a high percentage of seedlings for three wetlands (40.8–80.9%), but not for the fourth site (4.2%). Lythrum salicaria, Typha sp., and Ludwigia palustris were common species based on relative seedling density for three seed banks, while Leersia oryzoides, Schoenoplectus tabernaemontani, and Alisma triviale were common species in the fourth site. Similarity indices between the standing vegetation and their respective seed banks, based on presence/absence data, were low (13–34%). Species richness and seedling densities were within the ranges of natural wetland seed bank studies.