Pollen assemblages as paleoenvironmental proxies in the Florida Everglades

Analysis of 170 pollen assemblages from surface samples in eight vegetation types in the Florida Everglades indicates that these wetland sub-environme nts are distinguishable from the pollen record and that they are useful pro xies for hydrologic and edaphic parameters. Vegetation types sampled includ e sawgrass marshes, cattail marshes, sloughs with floating aquatics, wet pr airies, brackish marshes, tree islands, cypress swamps, and mangrove forest s. The distribution of these vegetation types is controlled by specific env ironmental parameters, such as hydrologic regime, nutrient availability, di sturbance level, substrate type, and salinity; ecotones between vegetation types may be sharp. Using R-mode cluster analysis of pollen data, we identi fied diagnostic species groupings; Q-mode cluster analysis was used to diff erentiate pollen signatures of each vegetation type. Cluster analysis and t he modern analog technique were applied to interpret vegetational and envir onmental trends over the last mio millennia at a site in Water Conservation Area 3A. The results show that close modem analogs exist for assemblages i n the core and indicate past hydrologic changes at the site, correlated wit h both climatic and land-use changes. The ability to differentiate marshes with different hydrologic and edaphic requirements using the pollen record facilitates assessment of relative impacts of climatic and anthropogenic ch anges on this wetland ecosystem on smaller spatial and temporal scales than previously were possible. (C) 2001 Elsevier Science B.V. All rights reserv ed.