9313704 PARKER Many biogeographers, ecologists, population biologists, and other scientists have recognized that scale is an important factor to be considered in their research. Hierarchy theory has highlighted the need to evaluate the broader spatial scales inherent in regional environmental histories as a context within which ecological and genetic interactions occur at finer scales of resolution. In order to identify how regional processes of disturbance and regeneration relate to spatial patterns, age structures, and genetic composition of related species, this project will examine two types of sand pine (Pinus clausa) in Florida. Ocala sand pine occurs in peninsular Florida, while Choctawhatchee sand pine is present in the Florida panhandle. Both species exist in both coastal and inland locations, where they occupy similar environments, but their stands are separated by more than 100 km. The project will be conducted in two phases. The first will consist of collection of materials and data on the diameter and tree-ring structure of sample trees as well as soil, foliage, and other environmental data for 18 representative sites. This information will be evaluated through detailed allozyme analyses to determine genetic and ecological variations between Ocala and Choctawhatchee sand pine. During a second phase of research, the demographic and genetic structure of four or five representative stands will be mapped in detail. This mapping will permit assessment of the ways that environmental and disturbance histories have affected each kind of sand pine. Of particular concern to the experienced team of geographers and population biologists undertaking this project is degree to which the dispersion of different trees are related to differences in the scales of disturbance (such as localized canopy fires vs. wide-spread wind damage from hurricanes). Attention also focuses on the extent to which these differences are related to finer-scale variations in g enetic structures within populations. This focused case study of variations among two species of Florida sand pine will provide valuable tests of hypotheses related to a broader range of topics. In addition to providing new insights regarding the possible impacts of Quaternary sea- level change on the isolation and genetic differentiation of species, the results of this research will shed light on multi- scale relationships among site characteristics, disturbance ecology, and the genetic structure of vegetation. ***
