Covel R. McDermot1, Vince D’Amico2, and Tara L.E. Trammell1 Acer rubrum L. physiological and biochemical response to urbanization and plant invasion in urban forest fragments Covel R. McDermot1, Vince D’Amico2, and Tara L.E. Trammell1 1Department of Plant and Soil Sciences, University of Delaware, Newark, DE; 2USDA Forest Service, Newark, DE INTRODUCTION RESULTS Urbanization: City Size Urbanization: City Size Growing cities and increased urban anthropogenic activities results in increased: reactive nitrogen (N) deposition heavy metals deposition nonnative plant invasion The goal of this study was to measure the chlorophyll and carotenoid concentrations, essential nutrients, heavy metals, and δ15N in red maple leaves in urban forests in two cities (i.e., Philadelphia, PA and Newark, DE) and in response to sub-canopy multiflora rose invasion. Hypotheses: Red maple trees in Philadelphia, PA will have higher chlorophyll and carotenoid concentrations than trees in Newark, DE despite potential deficiencies in essential nutrients and toxic metals in Philadelphia. Sub-canopy multiflora rose invasion will decrease chlorophyll and carotenoid concentrations due to reduced N availability. Are pigment concentrations higher in red maple (Acer rubrum L.) leaves in Philadelphia than Newark? Yes – red maple leaves have higher chlorophyll and carotenoid concentrations in Philadelphia 4. Are there differences in leaf δ15N between Philadelphia than Newark? Yes – δ15N is significantly enriched in Philadelphia compared to Newark due to: 1) enriched 15N sources or 2) greater soil N cycling rates and associated 14N losses * * 2. Do leaf nutrients and metal concentrations indicate stress in Philadelphia versus Newark urban forests? YES – red maple trees indicate plastic adaptation to stress in Philadelphia More enriched [Mg] CONCLUSION [Mn] Urbanization Our results suggest red maple trees in Philadelphia, PA demonstrate plastic adaptation response to greater metal concentrations and lower nutrient availability. We observed: greater chlorophyll and carotenoid concentrations in Philadelphia red maple leaves greater Al and Pb in Philadelphia lower Mg and Mn in Philadelphia Plant invasion Our results suggest multiflora rose invasion does not exert stress response in red maple trees Future directions Investigate red maple tree biochemical and morpho-phenological parameters across cities Investigate N cycling (soil N mineralization, N resorption) across cities and with plant invasion METHODS Long-term urban forest study sites (FRAME ) [Pb] Fig. 1. Fragmented forests across northern DE (Newark) and southeastern PA (Philadelphia). Invasion: sub-canopy multiflora rose 3. Did sub-canopy M. rose invasion influence leaf pigment concentration? No – chlorophyll and carotenoid concentrations were similar with and without rose invasion http://sites.udel.edu/frame/research/ Experimental design and sampling 79 red maple trees (dbh: 7.5 – 23 cm) from five forests in Newark, DE (40 trees) and five forests in Philadelphia, PA (39 trees) were selected 49 trees with no sub-canopy invasion and 29 trees with sub-canopy invasion Lower canopy leaves and sub-canopy soil were collected at peak growing season from July 17 until August 13, 2016 ACKNOWLEDGEMENTS Initial data suggests no differences in essential nutrients (e.g., Mg, Mn) or toxic metals (e.g., Al, Pb) in red maples trees with sub-canopy rose invasion and without sub-canopy rose invasion. We thank Rob Rose for leaf and soil collection, Nathaly Rodriguez for sample preparation, Deb Jaisi for isotope analysis, and Karen Gartley and Caroline Golt for foliar nutrient and heavy metal analyses. We thank the University of Delaware Research Foundation for funding.