title: Effects of Elevated Atmospheric Carbon Dioxide and Tropospheric Ozone on Phytochemical Composition of Trembling Aspen ( Populus tremuloides ) and Paper Birch ( Betula papyrifera ).
abstract: Anthropogenic activities are altering levels of atmospheric carbon dioxide (CO2) and tropospheric ozone (O3). These changes can alter phytochemistry, and in turn, influence ecosystem processes. We assessed the individual and combined effects of elevated CO2and O3on the phytochemical composition of two tree species common to early successional, northern temperate forests. Trembling aspen (Populus tremuloides) and paper birch (Betula papyrifera) were grown at the Aspen FACE (Free-Air Carbon dioxide and ozone Enrichment) facility under four combinations of ambient and elevated CO2and O3. We measured, over three years (2006-08), the effects of CO2and O3on a suite of foliar traits known to influence forest functioning. Elevated CO2had minimal effect on foliar nitrogen and carbohydrate levels in either tree species, and increased synthesis of condensed tannins and fiber in aspen, but not birch. Elevated O3decreased nitrogen levels in both tree species and increased production of sugar, condensed tannins, fiber, and lignin in aspen, but not birch. The magnitude of responses to elevated CO2and O3varied seasonally for both tree species. When co-occurring, CO2offset most of the changes in foliar chemistry expressed under elevated O3alone. Our results suggest that levels of CO2and O3predicted for the mid-twenty-first century will alter the foliar chemistry of northern temperate forests with likely consequences for forest community and ecosystem dynamics.
authors.affiliation: Department of Entomology, University of Wisconsin-Madison, Madison, WI, 53706, USA. jjcouture@wisc.edu.|Departments of Entomology and Forestry and Natural Resources, Purdue University, West Lafayette, IN, 47906, USA. jjcouture@wisc.edu.
authors.forename: John J
authors.initials: JJ
authors.lastname: Couture
authors.affiliation: Department of Entomology, University of Wisconsin-Madison, Madison, WI, 53706, USA.|National Ecological Observatory Network, Boulder, CO, 80301, USA.
authors.forename: Timothy D
authors.initials: TD
authors.lastname: Meehan
authors.affiliation: Department of Entomology, University of Wisconsin-Madison, Madison, WI, 53706, USA.
authors.forename: Kennedy F
authors.initials: KF
authors.lastname: Rubert-Nason
authors.affiliation: Department of Entomology, University of Wisconsin-Madison, Madison, WI, 53706, USA.
authors.forename: Richard L
authors.initials: RL
authors.lastname: Lindroth
mesh_terms: D029662:Betula / Q000187:drug effects* / Q000378:metabolism; D050260:Carbohydrate Metabolism / Q000187:drug effects; D002245:Carbon Dioxide / Q000494:pharmacology*; D008031:Lignin / Q000378:metabolism; D009584:Nitrogen / Q000378:metabolism; D010126:Ozone / Q000494:pharmacology*; D010636:Phenols / Q000378:metabolism; D064209:Phytochemicals / Q000378:metabolism*; D018515:Plant Leaves / Q000187:drug effects / Q000378:metabolism; D032107:Populus / Q000187:drug effects* / Q000378:metabolism; D013634:Tannins / Q000378:metabolism
chemical_list: D010636:Phenols; D064209:Phytochemicals; D013634:Tannins; D002245:Carbon Dioxide; D010126:Ozone; D008031:Lignin; D009584:Nitrogen
keywords: Aspen FACE; Atmospheric change; Betula papyriferia; Phytochemistry; Populus tremuloides