A Preliminary Investigation into Responses of Resurrection Fern to Saltwater Inundation

Abstract

Salt water inundation from storm surges caused by hurricanes or northeasters is an episodic phenomenon which may have great impact on coastal vegetation community structure (Clark, 1990; Hayden et al., 1991). Recent hurricanes, such as Hugo (1989) and Andrew (1992) produced large storm surges that affected maritime forest for many miles of coastline in the southeastern United States. Although many trees succumbed to extreme physiological stress produced by the overwash (Johnson and Young, 1992), epiphytic species, such as Tillandsia usneoides (Spanish Moss) and Polypodium polypodoides (Resurrection Fern), also may have been adversely affected. Polypodium polypodioides occurs in maritime forests where it is commonly found growing in large colonies on lower branches of Quercus virginiana (Live Oak) (Cobb, 1956; Small, 1938). Dune and maritime forest ecosystems rely on nutrient inputs from salt spray (van der Valk, 1974; Art et al., 1974; Potts, 1976). Furthermore, epiphytic species of maritime forest derive cation minerals from salt spray inputs (Sheline et al., 1976; Schlesinger and Marks, 1977; Benzing, 1978). Although epiphytes are known to rely on nutrient inputs from salt spray, very little is known about responses of epiphytic species to higher concentrations of salinity resulting from inundation. Studies of responses of ferns to salt concentration have been few and generally focussed on terrestrial plants (Medina et al., 1990). The objectives of this study were to 1) investigate the basic levels of rehydration and photosynthetic responses of unstressed P. polypodoides and 2) investigate rehydration of ferns exposed to increasing levels of salinity stress and the effects of prolonged salinity exposure on plant survivorship.