Greenhouse mesocosms of freshwater marsh vegetation were exposed to a
simulated saltwater intrusion event followed by a recovery period duri
ng which water levels and interstitial water salinity were adjusted ov
er a range of conditions. Virtually all above-ground vegetation, inclu
ding the three dominant species, Sagittaria lancifolia L., Leersia or
oryzoides (L.) Swartz, and Panicum hemitomon Schultes, was killed by t
he initial saltwater intrusion event. P. hemitomon did not recover, bu
t S. lancifolia and L. oryzoides, as well as many of the other species
initially present, exhibited some ability to recover depending on pos
t-saltwater intrusion conditions. Increasingly harsh recovery conditio
ns (for freshwater marsh vegetation), including more reduced soil cond
itions, higher interstitial salinities, and higher interstitial sulfid
e concentrations were associated with decreased live above-ground biom
ass and species richness. The effect of elevated salinity on vegetativ
e recovery became more pronounced under flooded conditions. This exper
iment illustrates that the response of a freshwater marsh community to
the longterm disturbance effect of a transient saltwater intrusion ev
ent will be strongly influenced by post-intrusion salinity and water l
evels.