THE USE OF CLINTONIA-BOREALIS AND OTHER INDICATORS TO GAUGE IMPACTS OF WHITE-TAILED DEER ON PLANT-COMMUNITIES IN NORTHERN WISCONSIN, USA

We examined how woody and herbaceous plant frequency cover, and overal l species diversity have responded to regional variation, both histori c and recent, in white-tailed deer densities in the Apostle Islands an d nearby Wisconsin mainland. We observed lower frequencies of several woody species, including mountain maple (Acer spicatum), yellow birch (Betula alleghaniensis), and mountain-ash (Sorbus decora), in areas of high deer densities. Higher historic (1950s and 1960s) and recent (19 80s and 1990s) estimated deer densities tended to depress the frequenc y of Canada yew (Taxus canadensis). The proportion of unbrowsed sugar maple(A. saccharum) twigs at a site also decreased predictably with de er density, as did the frequency of bluebead lily (Clintonia borealis) . Frequencies of wild sarsaparilla (Aralia nudicaulis), Canada mayflow er (Maianthemum canadense), and Clintonia borealis decreased in areas of historically high deer density. We also observed that herbaceous sp ecies richness and frequency and percent cover of C.borealis decreased with recent increases in deer density. Path analyses of C. borealis f requency and species richness suggest that deer have both immediate an d persistent effects on herbaceous community structure. Population siz e and scape height in C. borealis may provide reliable and efficient i ndicators for the impact of deer on both common and rare herbaceous sp ecies.