VEGETATION OF A FRESH-WATER DUNE BARRIER UNDER HIGH AND LOW RECREATIONAL USES

The 27.4 km freshwater dune barrier on the eastern shore of Lake Ontar io protects an extensive system of high quality wetlands. The vegetati on was pre viously undescribed, and development pressures required man agement decisions for which data were needed. The objective of this st udy was to describe and compare the vegetation under high and low recr eational use. We found four community types using hierarchical classif ication (TWINSPAN): (1) Ammophila breviligulata (beachgrass) (2) Toxic odendron radicans-Vitis riparia-Populus deltoides (brushland) (3) Quer cus rubra-Acer rubrum (forest), and (4) Alnus incana (thicket). Recipr ocal averaging ordination displayed communities along a first gradient of distance from the beach. A second gradient is likely related to di sturbance. Species composition was similar in beachgrass and brushland communities under high and low recreational use. Under low use, fores t and shrub thicket were present on the back of the barrier, but were absent under high use. Species richness and ground cover of vegetation , and density of colonizing species were lower on equivalent physiogra phic zones under high compared to low recreational use.