PARENT SESSION
Poster Session # 9: Herbivory.
Tuesday, August 5 Presentation from 5:00 PM to 6:30 PM. SITCC Exhibit Hall B.
The effects of Key deer (Odocoileus virginianus clavium) herbivory on forests in the Florida Keys.
Barrett, Mark*,1, Stiling, Peter1, 1 University of South Florida, Tampa, Florida, USA
ABSTRACT- This study examined the effects of herbivory on native plant species by the endangered Florida Key deer (Odocoileus virginianus clavium), which have increased from approximately 50 animals in the1950s to over 700 at present. To assess deer impacts, over 250 stratified vegetation transects were conducted in hammock, pineland, buttonwood, and mangrove habitats throughout 13 islands (categorized into deer densities of high, intermediate, and low). Also, six exclosures were established in hammock and pineland on a high-density deer island. Transect data indicated very low densities of preferred woody plant species less than 1.2m in height on islands with high deer densities. Hammock exclosures showed a mean increase in height of preferred woody species, while pineland exclosures exhibited a mean increase in percent cover of herbaceous vegetation. Using cut stems of 16 native woody species in cafeteria feeding trials, it was shown that deer highly preferred the same plant species that were found in low densities in the transect samples. Furthermore, numerous nursery plants of eight native species set in hammock and mangrove habitats on six Keys showed very high herbivory rates on preferred plant species while the non preferred species remained untouched. The data suggest that on islands of high deer densities preferred plant species may fail to regenerate while unpalatable plant species become dominant. Therefore, a balance must be found between increasing Key deer numbers and maintaining their habitat.
Key words: herbivory, deer, endangered, Odocoileus