BULLETIN FLORIDA MUSEUM NATURAL HISTORY VOL. 38 PT. 1 (3)


 Percent cover values were used to calculate the dominant species in each pond
basin and for all ponds combined using the 1989 and 1990 transect data. The top
three species were chosen as co-dominants from a list of total percent cover ranked
from highest to lowest.
 The floristic similarity between sites was determined using Sorensen's index of
 similarity (SI)(Mueller-Dombois and Ellenberg 1974). This index was calculated
 from species presence/absence and transect data from 1989 and 1990. It is
 computed as follows:

 SI = 2C X 100 A = # species, site 1
 A+B B = # species, site 2
 C = # species, common
 to both sites

 The results from the calculation of similarity indices were used to compare
species composition in patterns of zonation previously reported in the literature and
determine if similar patterns were present in the study ponds.
 To determine if the vegetation of each pond corresponded to an index value
indicative of wetland, species identified within quadrats were categorized by their
wetland indicator status and given an associated ecological index value (El) (Table
2) (Reed 1988; Wentworth et al. 1988). Ecological index values range from 1, for
obligate wetland species, to 5, for obligate upland species. Plus (+) and minus (-)
designations specify, respectively, the higher (more frequently found in wetlands)
or lower (less frequently found in wetlands) part of the frequency range for a
particular species. When assigning the El, species with a plus received 0.5 less
than the El for that category and species with a minus received 0.5 more than the
El for that category. Plants identified only to genus were assigned the maximum
indicator status category and the maximum El if there were differences within the
genus. A plant community consists of hydrophytic vegetation if visually estimated
percent cover of obligate wetland species (OBL) and facultative wetland species
(FACW) exceeds coverage of facultative upland species (FACU) and obligate
upland species (UPL) or if the El < 3 (USEPA 1989; USEPA 1991).
 Wetland index values (WIV) were calculated for each quadrat for each transect
across all ponds and all years using weighted averages of the percent cover data
(Wentworth et al. 1988). To calculate this index, relative abundance (R) of each
species in each quadrat was determined as percent cover of each individual species
divided by the total percent cover of all species in that quadrat. Calculation of the
WIV involved taking the sum of products of the relative abundances and ecological
index values of all species in each quadrat, divided by the sum of all the relative
abundances, as follows:

 WIV = Z (RX EI) R = Relative abundance
 ER El = Ecological index value