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Show COLLEGE OF SOCIAL & BEHAVIORAL SCIENCE UNDERGRADUATE RESEARCH ABSTRACTS STABLE ISOTOPE VARIATION IN PLANTS WITHIN RANGE CREEK CANYON Mallorie Owens (Michael Lewis, Joan Brenner-Coltrain) Department of Anthropology University of Utah Stable isotope analysis is routinely used in archeological diet reconstruction. The ratios of Carbon and Nitrogen isotopes differ in terrestrial plant and animal resources, and the relationship between total diet and bone collagen isotope ratios has been experimentally established, allowing for the reconstruction of ancient diets through isotope mixing models. This technique has been applied extensively in the American West, and has contributed substantially to our understanding of the Fremont, a prehistoric mixed horticultural/foraging population in Utah. Successful application of the mixing model requires an accurate characterization of the isotopic ratios of possible food items. In terrestrial food webs, factors influencing carbon isotope ratios include: for animals, trophic level, digestive physiology and prey choice; and for plants, photosynthetic pathway, elevation, humidity and temperature. This study explores isotopic variability in wild food plants from Range Creek Canyon, Utah, the site of a University of Utah field station and one of the best-preserved areas of Fremont archeology. Roughly 160 samples of ethnographically important food plants were collected from Range Creek Canyon in September 2012, including: Atriplex canescens, Atriplex confertifolia, Opuntia ficus-indica, Typha sp, Rhus integrifolia, and Pinus cembroides. Samples were taken from elevations between 1300 and 2067 meters, spanning the biological communities of mixed Conifer forest, Pinon-Juniper woodland and Greasewood Saltbush scrub. These communities cover an elevational temperature/moisture gradient, which contributes to isotopic variation in plants with C3, C4 or C A M photosynthetic pathways. Plants utilizing the CAM, C3 and C4 photosynthetic pathways were sampled from multiple elevations within the canyon. Samples were dried, powdered with mortar and pestle. Isotope analysis was carried out on a Finnigan M A T Delta Plus mass spectrometer with Carlo Erba EA1110 C H N interface at the Stable Isotope Ratio Facility for Environmental Research (SIRFER) on the University of Utah campus. While Analysis is ongoing, partial results indicate a statistically significant elevational trend for Rhus (C3) and Opuntia (CAM) and suggest a 1 -2%o change in d13C values across 600m of elevational change in Range Creek Canyon. These preliminary results emphasize the need for adequate sampling strategies during archeological diet reconstruction, and in particular the necessity of collecting samples representative of the environmental variation throughout the hypothesized foraging catchment. Mallorie Owens Joan Brenner-Coltrain 77 |