1. 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
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.