© File copyright Colin Purrington. You may use for making your poster, of course, but please do not plagiarize, adapt, or put on your own site. Also, do not upload this file, even if modified, to third-party file-sharing sites such as doctoc.com. If you have insatiable need to post a template onto your own site, search the internet for a different template to steal. File downloaded from terdesign. Introduction The term woodland refers to a variety of different habitats which share an open understory, a relatively open canopy, and plentiful ground flora [Nelson, 2010]. Pinus strobus (eastern White pine) is a coniferous gymnosperm with a natural range extending from the northeastern United States down to northern Georgia and Tennessee. However, the species is not native to the Domain. Although White pine groves are allowed or encouraged to grow in several locations across campus because of their aesthetic appeal, the colonization of a woodland habitat by P. strobus caused a conservation response. We hypothesize that white pine displaces hardwoods within woodland habitats on the Domain. Alternatively, white pine could occupy a niche within the sub-canopy that is not typically filled by native species in woodland habitats. Materials and methods Location: The invaded site was located near the University gates, across from the entrance sign, in Sewanee, TN. The site was bounded by University Avenue to the south and a loop of Beckwith’s Point Trail to the north, east, and west. Figure 1. Aerial map of data collection sites. Methods: Four sites were chosen along the ridge line non-randomly for proximity to White pine specimens. Circle plots of 80 square-meters were established around a rebar marker. All trees, divided between invasive White pine and native species, greater than 2 meters and less than canopy height were sampled. After measurement,. All invasive pine trees were removed January 2013 during a Conservation Biology lab project. Materials and Methods Future Methods: White pine will continue to be removed as it recolonizes the study site. After 5 and 10 years, our study will be repeated to examine woodland community structure in the absence of white pine. Figure 2. View from plot 1 looking south-east across the study site. The open understory and relatively open canopy are visible. Results Figure 3. Bar chart showing understory density at each plot for White pine and native tree specimens taller than 2m and shorter than canopy height. Site 1 contains 21 percent white pine. Site 2 contains 20 percent white pine. Site 3 contains 92 percent white pine. Site 4 contains 29 percent white pine. Conclusions Following the removal of white pine, native hardwoods may either re-colonize the niches formerly occupied by the white pine or the hardwoods may be unable to exploit the resources necessary to replace them. Although other research suggests that white pine displaces native hardwoods in upland forests on the Domain, it is not clear what effect the limited resources of woodland habitats had on the plant community structure determined by our study. If our alternative “empty niche” hypothesis is confirmed, it would suggest that in this resource limited environment, white pine is able to capture resource space not being taken advantage of by native species. However, we expect that further studies will suggest that the white pine had competitively displaced the native hardwoods, by showing an increased understory density for native hardwoods. Drake Schutt and Daniel Williams 735 University Ave Sewanee TN, Literature cited Evans, J Personal communications. Nelson, P.W Woodland in The Terrestrial Natural Communities of Missouri. Missouri Natural Areas Committee. Richardson, D.M Ecology and Biogeography of Pinus. Cambridge University Press, Cambridge, England. USDA Forest Service Trees for Reclamation: White Pine. USDA Forest Service, Broomall, United States. White pine invasion of woodlands: Competitive displacement or "empty-niche" colonization? Expected Results Figure 4. Bar chart showing understory density for native trees taller than 2m and shorter than canopy height at each plot, assuming that native species replace the removed white pine. Under this scenario, white pine had displaced native hardwoods at our site. Figure 5. Bar chart showing understory density for native trees taller than 2m and shorter than canopy height at each plot, assuming that the “empty niche” hypothesis is correct. Under this scenario, resources within the woodland habitat that could not be exploited by native species had been exploited by white pine. Figure 6. View of the ridge-top woodland. An open understory with large spreading canopy trees is visible. Eastern red-cedar is evident in the background.