A Floristic Study of Weaver Creek Wetland, Santa Rosa County, Florida

Abstract

Steepheads (streams that originate from the bases of valley walls) create a unique freshwater wetland habitat. Currently, steepheads are known to exist only in the southeastern United States along the Gulf Coastal Plain. The biology of these habitats is relatively unknown. The objectives of this study were to provide a comprehensive list of vascular plant species in the wetland of Weaver Creek (a steephead stream in Santa Rosa County, Florida), to compare the upstream and downstream reaches of Weaver Creek, and to compile lists of previously reported species from steephead habitats. Fourteen sampling visits over a period of one year (2006-2007) were made to the study site. Every effort was made to cover the entire length of the creek and to collect all species while in flower or fruit. In addition to the species list, species and taxonomic (generic) richness, evenness (J’) and diversity (H’) were calculated for the study site. The Jaccard Index (JI) was used to compare the degree of floristic similarity between the upstream and downstream sections of the wetland. Species richness (102 species), evenness (J’ = 0.86) and diversity (H’ = 3.97) for the entire study site were all relatively high. Taxonomic/generic richness, evenness and diversity were high as well (67 genera, J’ = 0.95, H’ = 3.98). The degree of community similarity between the upstream and downstream sections of Weaver Creek was very low (JI = 13.33%). Because of this low degree of similarity between the two sections, species and taxonomic richness, evenness and diversity were calculated for each section of the creek to further illustrate the differences between them. The downstream section was both more rich and diverse than the upstream section. However, evenness was slightly greater upstream. This study added 68 species to the list of plants known to occur in steephead habitats. The richness and diversity of the study site illustrate the need for further scientific investigation into steephead habitats. The potential for studying the presence of genetically isolated populations and endemics, as well as rare species, in steepheads provides additional incentive to focus on these habitats.