Abstract Detail

Pteridology

Fawcett, Susan [1], Reznicek, Anton [2].

The Impact of White-tailed Deer Herbivory on Two Rare Asplenium Species in northeastern North America.

As early as 1947, Aldo Leopold recognized the devastating impacts of Odocoileus virginianus (White-tailed Deer) overabundance on the vegetation of northeastern North America, noting the disproportionate pressure on low-growing and palatable species. Although the impacts of White-tailed Deer herbivory have been relatively well-studied for woody plant species, where the long-term consequences may be evident by comparing canopy composition with understory regeneration, the impacts on herbaceous species has been more difficult to document. Thirteen species of Asplenium (Spleenworts) occur in the northeastern United States, with eight of the thirteen considered endangered in at least one state. Two rare species, Asplenium rhizophyllum and A. viride, are sympatric in Wisconsin, Michigan, Ontario, New York and Vermont. Because these species are evergreen, they are susceptible to herbivory year-round. In the present study, we analyze the impact of deer herbivory on growth rate of these two species at 40 locations across the zone of overlap of their geographic ranges. A key insight is that while Asplenium viride regenerates all new leaves each spring, Asplenium rhizophyllum maintains each leaf for longer than two years on average, making it potentially more vulnerable to herbivory, a finding corroborated by greater population declines on browsed versus un-browsed populations. The influence of other factors, including colony height, snow cover, and other climatic and ecological variables are also considered. The conservation of these rare species depends on an understanding of the factors influencing their survival, and White-tailed Deer herbivory has been an under-appreciated threat.

1 - University Of Vermont, 111 Jeffords Hall 63 Carrigan Drive, Burlington, VT, 05405, United States
2 - UNIVERSITY HERBARIUM, 3600 Varsity Drive, Ann Arbor, MI, 48108, United States

Keywords:
fern
herbivory
Conservation
Asplenium
Great Lakes
Ontario
New York
Michigan
Vermont
deer
Ecology
sympatry.

Presentation Type: Oral Paper
Session: 32, Pteridology III
Location: 105/Mayo Civic Center
Date: Tuesday, July 24th, 2018
Time: 4:30 PM
Number: 32010
Abstract ID:687
Candidate for Awards:Edgar T. Wherry award