Name: Brian Isbicki Email: email@example.com Poster Title:Upland oak regeneration response to prescribed fire and canopy gap disturbances Author(s):Brian Izbicki, Dr. Heather D. Alexander, and Dr. Brent R. Frey Abstract:In upland oak forests of the Appalachian hardwood region, fire suppression contributes to extensive oak regeneration problems and compositional shifts toward shade tolerant species. Prescribed fire may maintain upland oak by removing competing species and increasing understory light. Single and multiple (2x, 3x) fires were implemented over 3-yr and 5-yr periods. Each growing season, canopy cover, growth, basal diameter and survival were quantified for six seedlings groups. Gap size and age, are being analyzed to identify influences on composition and regeneration dynamics if prescribed fire is unsuitable for all management objectives. Preliminary results suggest single fires are ineffective at creating beneficial conditions for oak regeneration while multiple fires promote oak growth relative to competing species. This study could direct how prescribed fire can preserve upland oak ecosystems and provides information on upland oak regeneration in canopy gaps with continued fire suppression. UPLOADED FILE: 132585350544566900_southern_hardwoods_conference_brian_izbicki_2_15_2017.pptx
Name: Nicole Hornslein Email: firstname.lastname@example.org Poster Title: Water and nutrient use of mid-canopy Liquidambar styraciflua during Pinus taeda mortality Author(s): Nicole Hornslein and Heidi Renninger
Paste Abstract Here As forest ecosystems undergo change, it is likely that tree physiological functioning will alter with changes in resource demands. In the southeastern U.S., mortality of Pinus taeda (loblolly pine) due to southern pine beetle will impact the successional dynamic of forests, including changes in resource availability to suppressed hardwoods. Twelve mid-canopy Liquidambar styraciflua (sweetgum) individuals in a loblolly stand undergoing a mortality event were measured for water-use, photosynthetic capacity, and leaf nitrogen (N) concentration. Sweetgums next to dying pines used significantly less water than ones next to alive pines in every month. Vcmax and Jmax values did not significantly vary between sweetgums with respect to adjacency to dead or alive pines. Leaf N content was significantly higher post-mortality than pre-mortality in both green and senesced leaves. Throughout the course of the study, resorption rate of N was higher in sweetgums next to dying trees, however this rate did not significantly differ between pre-mortality and post-mortality. These results suggest that in less than a year after mortality, significant resource-use rates of sweetgum are already occurring and are likely to increasingly change in the upcoming years.
Name: Tyler Durbin Email: email@example.com Poster Title: Comparing Photosynthetic Capacities and Limitations Across Seedlings of Two Oak Species and Three Planting Stocks of Artificially Regenerated Oak (Quercus spp.) Seedlings Author(s):Tyler Durbin, Heidi Renninger, Andrew W. Ezell, A. Brady Self, Emily B. Schultz
Abstract: Oaks (Quercus spp.) are an important component of many ecosystems. They provide aesthetic, wildlife, and economic value while providing many ecosystem services such as clean air and water. Oak species typically have a difficult time regenerating without proper planning and foresight. Regeneration can be especially difficult on highly productive soils such as those found in the bottomlands of the southeastern United States due to the large amount of competition they face. Oak regeneration cannot always be accomplished through natural means using advanced regeneration. After large natural destructive events when advances planning was not able to be accomplished or when reforesting or afforesting an open area that does not have a seed source available artificial regeneration can be a viable option. In order to establish a stand using artificial regeneration it is important to select a seedling that can outcompete non-desirable species. This study compares two species (Swamp Chestnut oak (Q. michauxii) and Shumard oak (Q. shumardii)) and three planting stocks that consist of bare-root, conventional containerized, and a large potted (EKOgrown). Photosynthetic capacities of leaves were measured using a LI-6400XT Portable Photosynthesis System. Maximum photosynthesis/carboxylation results were determined using equations for non-linear regressions.
Name: Holden Miles Email: firstname.lastname@example.org Poster Title: One-year Oak Regeneration (Quercus spp.) Responses to Midstory Control and Partial Harvest Treatments Author(s): Charles H. Miles1, Andrew W. Ezell3, Heidi Renninger2, John Willis2, A. Brady Self2, Emily B. Schultz2 James C. Rainer4
Abstract: Increased oak regeneration benefits timber production as well as a number of wildlife species that are found within bottomland hardwood systems. Partial harvesting and midstory control are two silvicultural operations used to increase light availability, which is essential for oak seedling survival. Oak seedlings generally require 25% available light to survive, but closed canopy hardwood forests provide less than 10% (Gardiner and Hodges 1998). In addition to the reduction due to closed canopies, available light is also limited in these systems due to dense midstory components. Sivicultural operations such as partial harvest and midstory control may be used in conjunction to increase light availability on the forest floor. Six sites were chosen for this study to evaluate the effects of partial harvest and midstory control on light availability and oak regeneration responses. The study plan contained six treatments assigned with random residual basal areas replicated across the six study sites, which included 70ft2/ac, 60 ft2/ac, 50ft2/ac, 40ft2/ac, 30ft2/ac, and a non-treated control. Results showed a target basal area of 50ft2/ac in theory optimized oak regeneration for this study more significantly than any other treatments.
Name Mercedes Siegle-Gaither Email email@example.com Poster Title Using Deuterium and Oxygen-18 Stable Isotopes to Understand Mechanisms of Stemflow Generation as a Function of Tree Species Author(s): Mercedes L. Siegle-Gaither, Dr. Courtney M. Siegert, & Dr. Richard F. Keim
Paste Abstract Here Stemflow is a form of nutrient-enriched rain partitioning that redirects intercepted water from the forest canopy down tree trunks, creating biogeochemical hotspots at tree bases. Few studies have examined species-specific effects of bark structure and storm meteorological conditions on stemflow generation via stable isotope tracers. Stemflow volume and isotopic composition were measured over one year to determine (i) origins and pathways of stemflow water using stable isotopes, (ii) differences in stemflow generation mechanisms between tree species, and (iii) differences in stemflow generation mechanisms between storm events. Stemflow collars were installed on 18 trees of six species. Water samples were collected within 24 hours of individual storm events. Laser ablation spectroscopy showed that isotopic composition (δ2H) of stemflow (-20.08±10.18‰) is distinct from that of throughfall (-21.25±9.09‰) and precipitation (-15.49±10.03‰). The difference in isotopic composition of stemflow relative to precipitation signifies evaporation, suggesting that this pathway is composed of pre-event and event water. A bark-wetting experiment showed bark water storage capacity (BWSC) per trunk to be greatest in red oaks (86.4±21.5L), then white oaks (51.4±30.9L), and hickories (22.7±15.7L), respectively. Oaks with thick, continuous bark generate lower stemflow volumes and have higher BWSC; hickories tend to have thinner, irregular bark that leads to higher stemflow volumes and lower BWSC. Species-specific BWSC is thus a determining factor for stemflow generation during an event, and for how much pre-event water contributes to this flux in terms of volume and chemistry. Results suggest stemflow significantly impacts forest hydrology and microclimate based on interspecific differences in bark.
Name Zeima Kassahun Email firstname.lastname@example.org Poster Title Species-Specific Environmental Factors that Influence Sap Flow Rates of Nine Bottomland Hardwood Species Author(s): Zeima Kassahun and Dr. Heidi Renninger Paste Abstract Here With increases in global temperatures and drought occurrences due to climate change, bottomland hardwood forests (BLH) are expected to experience a shift in their established microclimates. As the climate shifts, certain tree species could be more negatively affected over more resilient species, leading to a shift forest composition. This study uses sap flow measurements to examine physiological response of hardwood trees to vapor pressure deficit (VPD) and soil moisture (SM). Results suggest that shagbark hickory and willow oak have significantly different responses to VPD between high vs low SM. This suggest these species are drought-sensitive. Additionally the data suggests willow oak and shagbark hickory began to drop their leaves earlier in the growing season compared to the other species. This could be explained by the abnormally low water variability that occurred towards the end of the growing season. This research can provide an accurate assessment of BLH tree species response to climate change.
Name Robert Hane Email email@example.com Poster Title Herbicide Application over Hardwood Afforestation site Release Morning Glory Author(s): Robert Hane, Joshua Adams, Michael Blazier Paste Abstract Here Herbicide application is an important step in successful hardwood afforestation. The purpose of our genetic herbicide trial was to determine which timing of herbicide application (Oust XP) was the most efficient at controlling the weeds and releasing untested hybrid sweetgum trees planted in 2015. Height and ground line diameter were measured for each tree prior to the growing season, and again at the end of the growing season. While taking measurements late in the growing season we noticed some of the trees were partially or completely covered by Smallflower Morning Glory (Jacquemontia tamnifolia). Enough trees were affected to warrant a full tally of the site for Morning Glory and determine if any causes were apparent. Rows receiving a treatment of Oust XP for herbaceous weed control were approximately ten times more likely to be bound by Morning Glory than the seedlings that were not treated with herbicide. Seedlings that were bound by Morning Glory had significantly more diameter growth than unbound seedlings, but there was no statistical difference in the height of the seedlings. Due to the fact that Morning Glory germinates in the summer it was able to take full advantage of the competition-free study plot and overtop the seedlings. It is thought that increased diameter growth exhibits a response to the Morning Glory overtopping seedlings.
Name Emily Babl Email firstname.lastname@example.org Poster Title Species specific mechanisms contributing to the mesophication of upland oak forests Author(s): Emily K. Babl, Heather D. Alexander, Courtney M. Siegert, John L. Willis Paste Abstract Here Upland oak forests of the eastern United States are shifting dominance towards shade-tolerant, fire-sensitive species, a transition often attributed to fire suppression. This shift has been hypothesized to lead to mesophication, a process where shade-tolerant, fire-sensitive species (mesophytes) create a cool, moist understory, thereby reducing fuel flammability and promoting their own proliferation at the expense of upland oaks. There have been few empirical studies identifying mechanisms used by trees to promote mesophication, and these studies have yet to extensively explore potential mesophytes outside of the red maple (Acer rubrum). We sampled four hypothesized mesophytes and two upland oak species across a gradient of sizes (20-60 cm DBH) in western Kentucky. We quantified canopy area, bark roughness and thickness, and leaf litter traits that may lead to differences in forest floor flammability. Preliminary results show that mesophytes have thinner and smoother bark than upland oaks, which could contribute to greater stemflow funneling by these species and consequent reduction of leaf litter flammability. Delineating the potential mechanisms by which mesophytes could alter forest flammability through their bark, canopy, and leaf litter traits is essential for understanding future forest function and exploring options on how to successfully manage for preservation of upland oak forests.