Zonation is a conspicuous feature of coastal dune plant communities that is primarily caused by the recurrent deposition of sand and the differential tolerance of species to burial. Movement of sand inland through blowouts extends burial activity from the foredune complex to the lee slopes of parabolic dunes and into adjacent savannas. The magnitude of this burial activity shows spatial and temporal variability, and exerts strong differential selective pressure upon plants. The purpose of this study was to determine the relationship between plant community composition and burial activity in an ecotone between coastal dunes and oak savanna at the Pinery Provincial Park on Lake Huron. We sampled 10 stands on the lee slopes of parabolic dunes and five stands in the adjacent oak savanna using the point-quarter method and 1x1 m plots to obtain quantitative data for all species encountered. Species importance values (density + frequency + dominance) were entered into a detrended correspondence analysis (DCA), to examine patterns in plant community composition. Stands were distributed continuously along the first DCA axis (Eigen value = 40%), and separated into three groups according to a Two-Way Indicator Species Analysis (TWINSPAN). Stand scores on this axis were correlated to burial activity (-0.76, p < 0.01), and we defined these groups as i) active dunes, ii) semi-active dunes, and iii) stabilized dunes or savanna. Similarly, the 58 species we encountered in these stands separated into three groups according to the TWINSPAN classification. Based on apriori knowledge of distributions and burial tolerance, we identified these species groups as i)open dune, ii) transitional, and iii)prairie/savanna. Species richness, diversity, and vegetative cover all decreased in areas with recurrent sand burial. These results suggest that burial activity in the ecotone between coastal dunes and oak savanna produces a zonation of plant species according to their burial tolerance, which may be of importance in this globally imperiled habitat.

Key words: burial, coastal sand dunes, community ecology, oak savanna, ordination, zonation