Index of Presenters • page Error: Reference source not found
1 • Dennis D. Tarasi1, Robert K. Peet2
Do Invasive Plant Species Impact Community-Level Species Richness or Composition Patterns in Temperate Forests?
Ecologists have pondered the impact of invasive species on biodiversity for several decades, with no clear consensus emerging. We analyzed forested vegetation plots from across the Carolinas at multiple scales to determine if plant communities with significant cover of exotic species exhibit differences in species richness or composition patterns as compared to plots of similar community types that have not yet experienced significant invasion. Our data reveal no significant change in mean species richness at any scale between invaded and un-invaded plots. Perhaps with more time or greater dominance by invasives a different pattern will be observed. However, species composition patterns noticeably differ between the two groups of plots. This result suggests that invasive species presence in ecological communities can affect community structure and organization, but in ways beyond what can be captured by simple species richness values.
2 • S. Douglas Kaylor1, M. Joseph Hughes2, Jennifer A. Franklin1
Recovery Trends and Predictions of High Elevation Forest Change in the Southern Appalachian Mountains
We asked if high-elevation forests in the Southern Appalachians are recovering from the widespread mortality of the 1980’s and if there is evidence of forest composition shifts associated with hardwood encroachment. Great Smoky Mountains National Park supports some of the most extensive but threatened high-elevation forests in the southern Appalachians, which are dominated by the endemic Fraser fir (Abies fraseri). These forests are under considerable stress due to the balsam wooly adelgid (Adelges piceae), indirect and direct effects of pollution, and shifts in climate. Overstory and understory composition, mortality and recruitment were measured in thirty-seven 20x20m plots in 1990, 2000, and 2010 on 5 mountain peaks in the Great Smoky Mountains, representing almost the entire range of spruce-fir forests within the park. We created a stage-class population model to make predictions about future forests dynamics. Our population model predicts a mosaic of recovery across the landscape. Results show a decline in mortality rate over the study period, as well as an increase in forests with higher densities of canopy and sub-canopy fir. We also found no significant overall increase in the proportion of hardwoods, but with substantial variance among sites.
1 Dept of Forestry, 2 Dept of Ecology and Evolutionary Biology: University of Tennessee, Knoxville, TN
3 • Jonathon K. Loyd1, Steven Murphree
A Comparative Study of Wildlife Diversity in an Old-Growth and Adjacent Secondary Growth Forest in Davidson County, Tennessee
Secondary growth forests typically have reduced biodiversity when compared to primary or old-growth forests. The Hill Forest State Natural Area is a 91.4 hectare old-growth forest in Davidson County buffered from residential areas by a secondary forest. Motion-detecting wildlife cameras provide a convenient way to determine the presence and relative abundance of wildlife in natural areas. Three wildlife cameras were placed in the old-growth forest and three in the adjacent secondary forest to monitor wildlife activity. Following previous studies, which have shown that old growth forests tend to have greater biodiversity than the secondary growth forests, we hypothesized that the old-growth forest would have greater wildlife diversity than the secondary growth forest. A preliminary analysis of photographs from each forest showed a higher diversity of wildlife in the adjacent secondary forest. A complete analysis including a contingency table produce a p-value less than 0.05, indicating a significant difference between the two forests and therefore rejecting the hypothesis
1 Biology, Belmont University, Nashville, TN
4 • Gabrielle King, Wayne Rossiter
Assessment of the Roles of Endothermy and Ecothermy in Food Chain Length
It has been widely observed that aquatic ecosystems produce food chains that are longer than those of terrestrial systems. Several explanations exist for this pattern, including the difference in autotroph characteristics between the two types of environments, differences in carbon to nitrogen to phosphorous ratios of aquatic and terrestrial autotrophs and herbivores, and food chain length being governed by resource availability. However, the potential correlation between food chain length and the relative proportions of endothermic or ectothermic consumers remains unexplored. Endotherms have much higher size-specific metabolic rates than ectotherms and are less efficient at transferring energy to its own biomass; they must consume more resources relative to body mass (or population biomass). Thus, a logical prediction is that food chains containing endothermic organisms might be shorter because they are less efficient in transferring energy up trophic levels. Anecdotally, we have observed that terrestrial communities contain many more endotherms as opposed to aquatic food webs. To examine the role that endothermy might have in limiting food chain length, we utilized the GlobalWeb database (Thompson et al. 2012), which contains nearly 400 food webs from terrestrial, freshwater and marine systems. This database was supplemented with several other high-resolution webs from the literature. We calculated the distribution and mean length of all food chains in each system, and considered species richness, taxonomic resolution, the relative proportions of endotherms and ectotherms, the frequency of omnivory and the relative number of endotherms on each trophic level as explanatory variables.
Dept of Biology, Waynesburg University, Waynesburg, PA
Effect of Census Method and Season on the Number and Types of Vocalizations Uttered by Barred Owls in the Area Surrounding Reelfoot Lake, Tennessee
Barred Owls (Strix varia) are reportedly common in northwest Tennessee, however, a standardized census methodology has not been established. In addition, timing of breeding events are not well documented. Some Barred Owl vocalizations have been described and assigned possible functions. We hypothesize that owls may vary the frequency of call types depending on events in their life cycle. Our goals were to investigate the influence of census method and season on the detection of owls and study seasonal variation in the number and types of calls uttered. We conducted 5 and 10 min silent counts prior to playback of who-cooks-for-you-for-y’all calls followed by 5 and 10 min post-playback counts. Ten min silent counts were more effective at detecting Barred Owls than 5 min silent, but 10 min post-playback counts were the most effective. A similar number of calls were detected during 10 min silent counts and 10 min post-playback counts. While playback did not increase the rate of vocalizing, we observed owls moving closer to the source of the stimulus making them easier to detect. We identified 11 types of calls in the field. Some calls were uttered at increased frequency post-playback suggesting possible territorial functions. To look for seasonal differences, we divided the year into 3-month intervals: nest prospecting, nesting, post-nesting, and dispersal seasons. We found no seasonal differences in the number of owls detected using 10 min silent counts. We heard significantly fewer calls during nest prospecting suggesting owls may be spending time less time on territorial defense.
Fish Communities in an Alabama Salt Marsh With Consideration of the Impact of the Deepwater Horizon Oil Spill Disaster
Intertidal salt marsh systems of the northern Gulf of Mexico are invaluable as nursery grounds, providing food and refuge for developmental stages of fish and invertebrates. The Deepwater Horizon disaster of April 2010 provided an opportunity to investigate salt marsh systems on Point aux Pins, on the Alabama coast. Data provided by NOAA indicated that the eastern side of the Point was lightly to moderately oiled in the Summer of 2010, while the western shoreline remained unaffected. Ecologically similar locations were identified on the impacted and un-impacted shorelines, and a sampling program was initiated to characterize the fish assemblage utilizing the two systems. Monthly collections were made with hand-held seines and other apparatus in similar microhabitats in tidal marsh creek systems on the eastern and western sides of Point aux Pins. Environmental data was collected in coordination with fish samples. Significantly more fish were collected from the un-impacted western tidal creek system. Both location and microhabitat were significant factors affecting abundance. Date was a highly significant factor affecting abundance, due to the seasonal utilization of the tidal creeks by early life history stages of dominant species. The un-impacted western tidal creek system also demonstrated slightly higher diversity. It is unclear if the observed differences are the result of oiling impacts or result from subtle environmental differences in the sampled microhabitats.
Climate-Growth Relationships for Yellow-Poplar Across a Structural and Site Quality Gradient in the Southern Appalachian Mountains
Individual tree growth is variable, driven by climate as well as by spatial patterns in forest types, stand structures, and site quality. Past dendrochronology studies linking tree growth with climate have failed to consider the interacting effects that site quality and stand structure have with variations in annual tree growth. This likely over-simplifies climate-growth relationships and the potential effect of climate change on both tree- and stand-level productivity. Quantitative information regarding the effects of climate on tree growth across a range of stand conditions is needed to inform management strategies that promote resilience (in terms of tree and stand-level productivity) under a changing climate. In 1961, 141 - 0.1 ha plots were established across a broad age and edaphoclimatic gradient in yellow-poplar stands throughout the southern Appalachians. Plots were thinned to varying levels of residual density, with detailed information on structure obtained every five years. In 2009, we collected increment cores from five yellow-poplar trees in 133 plots. Cores were processed using standard dendrochronological methods, and chronologies of annual basal area increment (BAI) were developed. We used BAI chronologies to quantify the relative importance of climate, stand structure, and site quality on annual growth. At the individual tree level, results suggest that reductions in stand density via thinning may ameliorate some of the deleterious effects climate can have on tree growth. These results may be used to develop management alternatives aimed at maintaining tree- and stand-level productivity and assess trade-offs among management scenarios under the context of a changing climate.
1USDA Forest Service, Southern Research Station, Asheville, NC; 2 Rocky Mountain Tree Ring Research, Inc., Fort Collins, CO
8 • Lora Sigmon-Chatham1, Alexander Krings1, Zeb L. Robinson2, Thomas Harris2, Gary Blank2, William Hoffmann1
Historic Forest Structure and Composition of the Xeric Hardpan Forest Community of the Picture Creek Diabase Barrens; Insights From Dendrochronology
Picture Creek Diabase Barrens (Granville Co., NC), is a Nationally Significant natural area, hosting numerous plant species of conservation concern. This site is located in a Triassic basin and mafic soils underlie the majority of the property. The resultant mafic soils allow for unique plant communities, containing multiple threatened and endangered species. The forest structure at the site has been modified through farming, logging, and military management over the past century and there is evidence that a much more open canopy existed than at present. Using dendrochronological techniques we seek to gain a better understanding of the historic forest composition and structure of the Xeric Hardpan Forest community type at the site. We here report the results-to-date, based on analysis of tree cores sampled from square hectare plots. Our core data will be synthesized with historic satellite images, land use records, and data from subplots designed to determine recruitment in order to better understand what factors have affected the composition of this community type over the past century, and to inform future land management practices.
1 Dept of Plant and Microbial Biology, North Carolina State University, Raleigh, NC.; 2 Dept of Forestry and Environmental Resources, North Carolina State University, Raleigh, NC
9 • Rima D. Lucardi1, Lisa E. Wallace2, Gary N. Ervin2
Introduction History and Hybrdization Modulate Propagule Pressure in a Successful Exotic Grass Invasion: Cogongrass (Imperata cylindrica) in the Southeast
Successful biological invasions have been directly attributed to the strength of propagule pressure. The quantity of introduced genetic information is comprised of genetic material and the frequency of introduction. Therefore, introduction history and hybridization are components contributing to the quantity of introduced exotic material and may outline the potential of nascent populations. Secondary invasions (associated spatial spread) by exotics are subject to these same principles. Here, we analyze population-level genetic variation of the globally invasive plant species, cogongrass (Imperata cylindrica) in the southeastern region of the U.S. Genetic-geographic structure elucidated population-level genomic alterations during invasion within an invaded range: from site(s) of initial introduction to the front(s) of secondary invasion. A total of 676 individuals were collected from the field. Amplified fragment length polymorphic (AFLP) markers were utilized for molecular analyses. Genetic diversity estimates and population structure were assessed on the state-level. Differential genetic and clonal diversity values were observed among all states, with generally higher values in the states receiving purported initial introductions (Mississippi & Alabama). Population structuring was consistent with two separate introductions (K=2; FST = 0.363, P<0.001) of foreign material, further supported by reduced clonal diversity in secondarily invaded states. Genetic data is consistent with documented introductions of foreign material into Mississippi and Alabama. Cogongrass invasion in other affected states are likely the result of secondary invasions; states with high observed genetic diversity (i.e. South Carolina & Florida) probably resulted from propagule rain and differential management practices between states.
1 United Stated Dept of Agriculture - Forest Service; 2 Dept of Biological Sciences, Mississippi State University
10 • Luke H. Turner, Wade B. Worthen
Community Structure of Dragonfly Assemblages and Effects on Parasitism Rate: A Test of the “Dilution Effect”
Parasitism rates often decline with increasing diversity as the density of susceptible hosts is diluted’ by non-susceptible species. We sampled dragonflies and their water mite parasites at seven ponds and lakes in northwest South Carolina and tested for this relationship. We also tested for developmental effects of parasitism by comparing the degree of bilateral asymmetry of ten wing characters between dragonflies with mites and those without mites, for three common dragonfly species. Sites were visited weekly, adult dragonflies were captured by aerial net and identified by species and sex, and the number of living mites was recorded. Dragonflies can starve mites by clogging mite mouthparts, so deflated (starved) mites were also counted. The left and right sides of Erythemis simplicicollis, Pachydiplax longipennis, and Libellula incestaindividuals were photographed, and ten characters on the left and right wings were measured with ImageJ software and compared for symmetry. The rate of mite parasitism varied significantly between sites (7-23%) and among species (1-48%).Perithemis tenera and Argia fumipennis showed some resistance to parasitism; only 1.4% of P. tenera individuals had mites, and 80% of parasitized Argia fumipennis had deflated mites. There were no indications of a dilution effect; there were no significant negative correlations between parasitism rate and any measure of dragonfly community diversity. In addition, parasitism did not reduce bilateral symmetry. Curiously, parasitized L. incesta individuals were more symmetrical than those without mites. Subsequent experiments will examine the nature of the resistance seen in Argia fumipennis and Perithemis tenera.
Biology Dept, Furman University, Greenville, SC.
11 • Andrea L. Rodriguez, Victor R. Townsend, Jr.
Leg Morphology of Cosmetid Harvestmen (Arachnida, Opiliones, Laniatores)
Scanning electron microscopy (SEM) is useful for identifying informative taxonomic characters. Recent SEM studies have revealed a diverse assortment of sensory and glandular structures on the legs of gonyleptoidean harvestmen. With the taxonomy of cosmetid harvestmen in need of major revision, the examination of the microanatomy of the legs may provide useful systematic information. In this study, we used SEM to compare the microanatomical features of leg IV of 12 cosmetid species, including several members of the genera Cynorta, Erginulus, and Paecilaema. For comparative purposes, we also examined the legs of gonyleptoidean harvestmen representing the Agoristenidae, Cranaidae, Gonyleptidae, Manaosbiidae, and Stygnidae. We observed considerable interspecific variation with regards to the size, shape and number of tubercles of male leg IV (femur, patella, tibia and metatarsus). Among the species examined, Erginulus spp. were most similar to each other with respect to the morphology of leg IV. We also observed the presence of rough pit glands on the femur and patella of the legs of all 12 cosmetid species. With the exception of Erginulus spp. and Eupocilaema magnum, rough pit glands were also present on the tibia. We observed rough pit glands on the legs of only two gonyleptoidean species including Rhopalocranus albilineatus (femur, patella, and tibia) and Zygopachylus albomarginis (patella and tibia). Our results indicate that rough pit glands on leg IV may be a derived character for the Cosmetidae that has not been previously reported.
Dept of Biology, Virginia Wesleyan College, Norfolk, VA
12 • Zachary J. Loughman
Life History of the New River Crayfish in Anthony Creek, West Virginia
The life history of Cambaruschasmodactylus (New River Crayfish) was studied in Anthony Creek, West Virginia from May through October 2011. Animals were collected monthly from a stream reach with two complete riffle/run/pool sequences. Reproductive and molt states along with morphometrics were recorded for all individuals encountered, after which, the majority of animals were returned to the stream. Monthly, 20-30 females were vouchered and dissected in the laboratory to determine monthly gonadal development. All ovigerous individuals encountered carrying eggs/instars were vouchered to determine egg/instar compliment values. Amongst adults two mass molts, one in May and another in September, occurred over the activity season. The majority of males molted from form I to form II in May and back to form I following the September molt. Females displayed active glair glands from May through late June, with oviposition occurring from July into early August. Females carried instars from September through the fall and possibly into winter. Ovigerous females had an average of 168 eggs/instars. Egg/instar complements was weakly correlate (r2 = 0.625) to carapace length. Age histogram analysis indicated six size cohorts within the population, with the largest individuals possibly six years old or older. From these results, it was concluded that C. chasmodactylus displays K selected life history traits relative to other crayfish taxa.
Dept of Natural Sciences and Mathematics, West Liberty University, West Liberty, West Virginia
13 • Suellen F. Pometto, Peter H. Adler, Charles E. Beard
Assembly of the lepidopteran proboscis by union of the two galeae has been thought to occur only at eclosion of the adult from the pupa. Our observations indicated that butterflies can reassemble separated proboscises, assisted by saliva production. The reassembly of the proboscis and the role of saliva were tested for the monarch butterfly, [Danaus plexippus] (Lepidoptera: Nymphalidae). The hypotheses were: (1) butterflies can reassemble a separated proboscis, (2) removal of saliva would impede reassembly, and (3) the reassembled proboscis can take up fluid. Seventeen reared butterflies were randomly assigned to three groups: (A) saliva collected into capillary tubes by manipulation of the proboscis for 5 minutes, (B) similar manipulation without removal of saliva, (C) no manipulation or removal of saliva. For each butterfly, the two galeae were separated through the distal two-thirds of the proboscis. Reassembly was evaluated by measuring: (1) time to achieve complete reunion of the galeae, and (2) diameter of the coil at 60 minutes after separation. All butterflies achieved 100% reunion of the galeae by 30 minutes. Both manipulated groups were similarly impeded, whether or not saliva was removed. To test restoration of functionality, butterflies were fed dyed sucrose water and placed in separate cages lined with filter paper. If no dye-colored gut exudate was produced on the filter paper after 24 hours, the butterfly was dissected. The presence of dye in the exudate or gut was found in 16 of 17 specimens, confirming successful feeding.
School of Agricultural, Forest, and Environmental Sciences, Clemson University, Clemson, SC