PARENT SESSION
Oral Session #57: Aquatic Ecology: Wetlands, Estuaries, Marine. Presiding: T. Klinger.
Wednesday, August 8, 2001. 1:00 PM to 5:15 PM. Hall of Ideas J.

Seed bank response after experimental manipulations of Phragmites australis in an inland salt marsh.

Carter, Christy¹, Ungar, Irwin¹, ¹

ABSTRACT- Zonal plant communities of annual halophytic species characterize an inland salt marsh in Rittman, Ohio. Recently, Phragmites australis (a non-native perennial invasive grass) has been observed establishing in the more saline areas of this marsh. Our goal in this investigation was to assess the response of the seed bank when experimental manipulations were applied to a monotpic stand of P. australis using a randomized block design. Each block contained three treated plots (Phragmites removed/leaf litter removed; Phragmites intact/leaf litter removed; Phragmites removed/leaf litter intact) and an untreated control (both Phragmites and leaf litter intact). All species present in the aboveground vegetation in each treatment and control plot were harvested at the end of the growing season. Soil collections were made monthly over a 12-month period to determine seed bank estimates. Percent frequency of species in the aboveground vegetation included Phragmites australis (100%), Atriplex prostrata (30%), Cyperus flavescens (17.5%), Aster subulatus (10%), and Salicornia europaea (5%). The greatest germination from the seed bank occurred in the Phragmites removed/litter removed treatment. No P. australis seeds were found from the soil collections, but seed density of other species was found to fluctuate throughout the year, indicating a transient seed bank. Even though P. australis does not produce a seed bank, it does reproduce vegetatively and may continue to replace the smaller light-requiring marsh species in the aboveground vegetation.

KEY WORDS: Phragmites australis, inland salt marsh, halophytes, seed germination