Abstract Detail

Recent Topics Posters

Leege, Lissa M [1], Kirby, Kevin [2].

Demography and Potential Deer Herbivory in Popuations of the Endangered Trillium persistens (Persistent Trillium).

Trillium persistens (persistent trillium) is an endangered herbaceous perennial that is restricted to a five-mile radius in the Tallulah-Tugaloo River system in northeastern Georgia and southwestern South Carolina, USA. Little is known about the demography of this rare plant or the threats to its fragmented populations. The objectives of this study were 1) to determine trillium population dynamics over a 3-year period in two sites (Panther Creek and Moody Creek) and 2) to determine the role of deer herbivory on the survivorship and growth of flowering individuals. To examine trillium demography, we monitored two populations by individually tagging and censusing plants of all life stages annually from 2011-2013, and developed matrix models to project population growth. To determine the effects of deer herbivory, we installed a cage experiment during 2011-2012. Two flowering T. persistens individuals in close proximity were identified; one was covered with a columnar chicken wire enclosure approximately 3m tall x 17cm in diameter, and the other was left un-caged, and accessible to deer. We installed 40 replicate pairs at each site. Plants were examined for herbivory two months after cage installation. Leaf area was measured prior to cage installation and one year later to determine plant growth. Trillium populations declined by 37% at Panther Creek and 63% at Moody Creek over the three growing seasons of the population study. Dormancy played a significant role in population dynamics: 21-70% of plants in each life stage at Panther Creek entered dormancy in 2011, while 7-23% of individuals returned from dormancy in 2012, with similar proportions during 2012-13 and at Moody Creek. Matrix projections incorporating dormancy transitions predict near stable to increasing populations at each site, despite declining numbers of individuals in the years surveyed. We found no evidence of deer herbivory in the cage experiment, but 79% of all plants experienced leaf loss from an unknown herbivore, even in the presence of cages. 2012 leaf area was on average 20% smaller than that of 2011, with a trend of greater reduction in plants that experienced herbivory. This study suggests that populations of this endangered species are projected to be stable over time in the two sites studied and that deer herbivory is not a threat to populations in the two growing seasons of the cage study.

1 - Georgia Southern University, Biology Department, P.O. Box 8042, STATESBORO, GA, 30460, USA
2 - Georgia Southern University, Biology, PO Box 8042-1, Statesboro, GA, 30460, USA

Keywords:
endangered plant species
Herbivory
Trillium persistens
projection matrix
dormancy.

Presentation Type: Recent Topics Poster
Session: P, Recent Topics Posters
Location: Exhibit Hall/Savannah International Trade and Convention Center
Date: Monday, August 1st, 2016
Time: 5:30 PM
Number: PRT014
Abstract ID:1203
Candidate for Awards:None