Document: PAB-3-83-8

The status of four endemic pine rockland herbs in the Florida Keys: Implication for long term management.

RUIZ, P.L.* and M.S.ROSS

Florida International University, Miami, FL 33199 USA ¹

Abstract:
The abundance, distribution and status of four endemic pine rockland herbs (Chamecrista lineata var. keyensis, Chamaesyce deltoidea ssp. serpyllum, Melanthera parvifolia , and Linum arenicola) were examined in the Florida Keys. Though populations of M. parvifolia and L. arenicola exist on the South Florida mainland, no populations of C. lineata or C. deltoidea ssp. serpyllum occur outside the pine rockland forests of the Florida Keys. Thus, their status within this isolated and restricted geographical range is of concern to conservation efforts, considering that pine rockland forests are a globally endangered plant community. Our study, thus, focused on five neighboring islands in the Lower Keys that have substantial pine rockland forests remaining. Sampling transects were established with evenly placed points (ca. 50 meters apart). At each point the density of each herb was recorded along with other plot variables. From this data we derived 16 habitat variables and created a fire history for each transect/point based on aerial photographs, fire records, and personal accounts. We then applied a principal component analysis to the habitat and fire history variables and thus reduced the data to four easily-interpretable composite factors. Our census revealed that the four herb species are restricted to one key (Big Pine Key). However, our analysis suggested that appropriate habitat is present on the other four islands (Little Pine Key, No Name Key, Sugarloaf and Cudjoe Keys), though such sites are less abundant than on Big Pine Key. We conclude from this that habitat and short term management practices are not limiting factors in the distribution of these species. Furthermore, the reestablishment of these herbs requires management strategies which integrate species reintroduction with effective fire management. However, we believe that long term sea level rise, through its direct (i.e. salt water intrusion) and indirect effects (i.e. fragmentation of once continuous pine rockland forest), is the fundamental factor controlling the status and vigor of these species on these islands.

Keywords: Chamecrista lineata var. keyensis, Chamaesyce deltoidea ssp. serpyllum, Melanthera parvifolia, Linum arenicola, Florida Keys, Pine rocklands and sea level rise

This abstract is being presented at: 4:00 PM in session:
Oral Session #33: Plant Demography.