Population Dynamics of the Rare Relict Trillium (Trillium reliquum)
Populations of the federally endangered relict trillium (Trillium reliquum Freeman) were surveyed for two years to determine status and reproductive success. By focusing on conserved populations and those with conservation potential, we intended to define how close existing conserved populations are to the recovery goal and determine any threats to populations that occur on protected lands. Identification of management needs and prioritizing conservation protection for existing populations were also study objectives. Specifically, we wanted to estimate the size of the trillium population (mature, juvenile, and reproductive individuals) at each site in each year (2011 and 2012) and on average; compare the density of the trillium population (mature, juvenile, and reproductive individuals) across years to determine whether populations are increasing, decreasing, or remaining stable; estimate herbivory damage; and, estimate the invaded proportion of plots at each site. Data was collected from 14 sites in Georgia and South Carolina. These survey efforts were successful in identifying where robust populations of the relict trillium occur to satisfy recovery plan objectives, and where protected populations of adequate size are missing. A regression analysis was used to identify patterns in herbivory and invasion and identify those sites with significantly higher rates of both. The proportion of points suffering from invasion in 2012 was not significantly different from that in 2011 and differences in invasion varied significantly among sites. These analyses did highlight sites where additional management efforts are warranted to ensure trillium population success.
1 School of Science and Technology, Georgia Gwinnett College, Lawrenceville, GA; 2 United States Dept of the Interior, Fish and Wildlife Service, Athens, GA
The Yellow-Bellied Glider, P. australis, of northeastern Australia dens in the hollows of E. grandis trees over 99.5 cm diameter at breast height in Wet Sclerophyll Forests. This study compared E. grandis trees in this size class possessing potential P. australis dens (den trees), with E. grandis trees of the same size without any potential of dens (non-den trees). This study investigates the role fire may play in the development of dens since it is known that fire increases tree susceptibility to termite and fungal infestations, facilitating tree hollowing which creates suitable P. australis dens. Den and non-den trees were compared for differences in respect to the number and size of fire hollows. Canopy and sub-canopy measurements were also taken surrounding the den and non-den trees. Den trees had significantly more fire hollows than non-den trees. Fire hollows were also significantly larger in den than in non-den trees, indicating that den trees were subjected to much higher intensity fires. The average number of trees found in the canopy was significantly higher around den trees, and the average number of trees in the sub-canopy was significantly lower around den trees than non-den trees. Results of this study imply necessity for high intensity fires in the Wet Sclerophyll Forest for the creation of suitable den habitats for P. australis gliders.
Guilford College, Greensboro, NC; 2 The School for Field Studies, Yungaburra, QLD, Australia
189 • Shannon E. Pittman1, Ranjan Muthukrishnan1, Natalie M. West2, Adam S. Davis2, Nicholas R. Jordan3, James D. Forester1
Mitigating the Invasive Spread of an Exotic Biofuel Crop, Miscanthus × giganteus
Herbaceous perennial crops are becoming a larger component of bioenergy production both in the United States and worldwide. However, there is growing concern that perennial crops pose a substantial risk of biological invasion as a result of the same traits that make them ideal for bioenergy production: low nutrient requirements, fast growth, and drought tolerance. Miscanthus x giganteus is a sterile perennial grass native to Asia which generates high fuel yeild even in northerly latitudes. Because of its low nutrient requirements, M. x giganteus has been proposed as an ideal biofuel crop for planting on marginal lands unfit for food production. A fertile variety of M. x giganteus was recently developed in an effort to decrease the costs associated with planting rhizomes of the sterile variety. However, no management practices are required by the Environmental Protection Agency to limit the spread of the fertile variety. We implemented a spatially-explicit population model of fertile M. x giganteus to determine the efficacy of potential management strategies on limiting or slowing the spread of the species. We found that implementation of buffer zones surrouding fields and early harvesting times could drastically reduce spread in some landscapes, but extensive spread was likely in all scenarios investigated. Fertile M. x giganteus may be planted in locations devoid of suitable habitat outside of planted fields, such as within corn fields, with limited risk of spread. However, if M. x giganteus is planted on marginal lands adjacent to potential habitat, buffer zones and early harvesting may substantially reduce the rate of invasive spread.
1 Dept of Fisheries, Wildlife, and Conservation, University of Minnesota, Saint Paul, MN; 2 Global Change and Photosynthesis Research Unit, United States Dept of Agriculture, Urbana, IL; 3 Dept of Agronomy and Plant Genetics, University of Minnesota, Saint Paul, MN
190 • Ryan Walsh1, Thomas Hancock2, Patrick Amico3
