Authors: James Dyer*, Ohio University
Topics: Biogeography, Geographic Information Science and Systems, Global Change
Keywords: oak forests, mesophication, climate change, water balance, presettlement
Session Type: Poster
Start / End Time: 3:05 PM / 4:45 PM
Room: Lincoln 2, Marriott, Exhibition Level
Presentation File: Download
Prior to Euro-American settlement, rectilinear public land survey methods involved setting corner stakes and noting adjacent trees, to aid later location of the surveyed boundaries. These “witness trees” provide an archival source of ecological information, which in combination with contemporary plot data extend our ability to capture long-term processes of tree-species replacements. Our previous research demonstrated not only an increase in mesophytic species in these oak-dominated forests, but a shift in realized niches: some taxa that decreased since settlement now preferentially occur on better quality sites, and species that increased expanded into lower quality sites. We hypothesized that topographic-driven variations in water balance can alter competitive relationships under drought conditions, leading to habitat shifts among tree species. A water balance explores the interactive relationship between energy and available moisture at a place. This study utilizes a GIS-based Water Balance Tool in combination with presettlement records to explore landscape-level changes under altered climatic conditions. I first characterized landscape patterns in moisture stress and demand using contemporary climate parameters. As a means to interpret shifts in dominant taxa along topo-edaphic gradients, I then explored alterations under increased drought stress. Dendroclimatological data indicate that the late twentieth century is among the wettest periods in the eastern US over the past 500 years, which would favor mesophytic species. Similarly, climate projections for the next century suggest conditions that may again favor drought-tolerant species. Results suggest that climatically-driven changes in potential habitat could influence fine-scale compositional changes.