COS 8-5
Mammalian herbivory on fourteen experimentally planted native hardwood tree seedlings of the Kentucky Bluegrass savanna-woodland community
Savanna communities are strongly influenced by disturbance regimes that affect plant composition and structure. It has been hypothesized that after the precipitous post-1500 decline in Native American populations and use of fire as a habitat management tool, the now globally endangered Kentucky Bluegrass savanna-woodland community may have been primarily maintained by large mammal (elk [Cervus canadensis] and American bison [Bison bison]) herbivory and other physical disturbances (e.g. trampling). Although these megaherbivores have been regionally extirpated, browsing by white-tailed deer (Odocoileus virginianus), eastern cottontail (Syvilagus floridanus) and various small rodent species (Microtus spp., Peromyscus spp., and Reithrodontomyssp.) appears to be a current limiting factor to the regeneration of remnant Bluegrass stands by impacting the establishment, survival, and growth of native hardwood tree seedlings. We established a large scale, long-term tree restoration project at the largest savanna-woodland remnant (Griffith Woods Wildlife Management Area, Harrison Co., KY) to understand how herbivory affects the establishment and growth of fourteen native hardwood tree species (n= 6,168 seedlings) common to Central Kentucky. We compare herbivory among tree seedling plots using a block design that included individual tree seedling protectors and herbaceous competition control using mowing and herbicide.
Results/Conclusions
Preliminary results suggest that seedling protectors and surrounding vegetation have influenced mammalian browsing, and further variation in herbivory is associated with particular seedling species and herbivore type. More specifically, rates of deer browsing are influenced by the presence or absence of vegetation, with higher rates of browsing occurring in unvegetated areas. However, the use of seedling protectors did not inhibit deer browse rates as much as vegetation. Rabbit herbivory decreased in the presence of seedling protectors, but the presence or absence of vegetation did not limit browsing to the same extent as that of seedling protectors. Deer browse occurred more often on Red Mulberry (Morus rubra) and White Ash (Fraxinus americana). Species preferences of rabbit were less distinct; however, both browser types consistently avoided Ohio Buckeye (Aesculus glabra). This research adds basic ecological knowledge about the individual tree species and the browsing behavior of native mammals, tests potential management practices that could be utilized in future Bluegrass savanna-woodland restoration projects and/or management of game animal populations, and re-establishes viable populations of tree species which provide beneficial wildlife habitat and food resources.