CLARKE, H. DAVID* AND VICKI FUNK. Department of Botany, Smithsonian Institution, Washington, DC 20560. - Analyzing checklists and using collections data to investigate plant diversity: An examination of five florulas from northeastern South America.
Five plant checklists from areas on and adjacent to the Guiana Shield
were analyzed and used to test hypotheses of the emergent properties
of the flora of northeastern South America. Checklists of Iwokrama,
Mabura Hill, and Kaieteur Falls (all three in Guyana), Central French
Guiana, and Reserva Ducke near Manaus, Brazil, which have only
recently been made available, were compiled and synonymized. Data
from checklists provide an attractive alternative to transect or plot
data because they are based on rigorously determined plants of all
habit types rather than the sterile vouchers of tree species often
used in plot or transect studies. Descriptive data were compiled for
the checklists regarding diversity, overlap, and endemism. Rankings
of diversity at the family level was subjected to Kendall's
coefficient of concordance of ranks test and Spearman rank correlation
coefficients to evaluate similarities among the five sites. A UPGMA
dendrogram was created from data for the presence or absence of
species shared by two or more sites. The results indicate greater
similarity of the three sites in Guyana and also of Central French
Guiana with Reserva Ducke, supporting a model of plant distributions
determined by the presence or absence of sandstone substrates rather
than disjunct between the Guiana Highland and low elevation areas of
the Guiana Shield. Relatively little overlap was found even between
adjacent areas with very similar abiotic environments, indicating that
plant diversity will not necessarily be protected by conserving
representative areas selected on the basis of general
characteristics.
Key words: biogeography, floras and florulas, floristics, Guiana Shield, Guyana