title: Photosynthesis and aboveground carbon allocation of two co-occurring poplar species in an urban brownfield.
abstract: Phytoremediation, a technique used to reclaim heavy metal-contaminated soils, requires an understanding of plant physiological responses to heavy metals. However, the majority of studies documenting heavy metal impact on plant functioning have been performed in laboratory or greenhouse settings. We predicted that increased soil heavy metal concentrations reduce photosynthesis and biomass production in trees growing in metal contaminated soil in a naturally re-vegetated urban brownfield. Leaf gas exchange, leaf carbon and nitrogen concentration, and tree biomass were recorded and compared for Populus deltoides and Populus tremuloides growing in an urban brownfield. The CO2compensation point (CCP) differed significantly between soil metal concentrations and species, with P. deltoides displaying a greater CCP and P. tremuloides displaying a lower CCP as soil metal concentration increased, despite no changes in dark respiration for either species. In terms of biomass, only total branch weight (TBW) and leaf area (LA) differed significantly between soil metal concentrations, though the difference was largely attributable to variation in diameter at breast height (DBH). Furthermore, TBW and LA values for P. deltoides did not decrease with increasing soil metal concentration. Soil metal concentration, thus, had minimal effect on the relationship between tree age and DBH, and no effect on relationships of tree age and height or LA, respectively. Significant differences between soil metal concentrations and species were found for δ15N (isotopic nitrogen ratio) while leaf nitrogen content (% N) also differed significantly between species. Long-term water use efficiency derived from carbon isotope analysis (iWUEisotope) differed significantly between trees grown on different soil metal concentrations and a significant species-metal concentration interaction was detected indicating that the two study species responded differentially to the soil metal concentrations. Specifically, P. tremuloides enhanced while P. deltoides reduced long-term iWUEisotopeas soil metal concentration increased, further emphasizing the importance of species and possible genotype selection for phytoremediation.
authors.affiliation: Department of Biological Sciences, Rutgers University, Newark, NJ, United States.
authors.forename: Diane
authors.initials: D
authors.lastname: Radwanski
authors.affiliation: Department of Landscape Architecture, Rutgers University, New Brunswick, NJ, United States.
authors.forename: Frank
authors.initials: F
authors.lastname: Gallagher
authors.affiliation: Department of Biology, Montclair State University, Montclair, NJ, United States.
authors.forename: Dirk W
authors.initials: DW
authors.lastname: Vanderklein
authors.affiliation: Department of Biological Sciences, Rutgers University, Newark, NJ, United States; Earth and Environmental Science Department, Rutgers University, Newark, NJ, United States. Electronic address: karinavr@andromeda.rutgers.edu.
authors.forename: Karina V R
authors.initials: KVR
authors.lastname: Schäfer
mesh_terms: D001673:Biodegradation, Environmental; D018533:Biomass; D002244:Carbon / Q000378:metabolism*; D005838:Genotype; D019216:Metals, Heavy / Q000494:pharmacology; D009584:Nitrogen / Q000378:metabolism; D010788:Photosynthesis / Q000187:drug effects / Q000502:physiology; D018515:Plant Leaves / Q000187:drug effects / Q000378:metabolism; D032107:Populus / Q000187:drug effects / Q000235:genetics / Q000378:metabolism*; D012989:Soil Pollutants / Q000494:pharmacology; D014197:Trees / Q000378:metabolism*
chemical_list: D019216:Metals, Heavy; D012989:Soil Pollutants; D002244:Carbon; D009584:Nitrogen
keywords: Heavy metals; Photosynthesis; Populus deltoides; Populus tremuloides