title: Tropospheric O(3) compromises net primary production in young stands of trembling aspen, paper birch and sugar maple in response to elevated atmospheric CO(2).
abstract: Concentrations of atmospheric CO(2) and tropospheric ozone (O(3)) are rising concurrently in the atmosphere, with potentially antagonistic effects on forest net primary production (NPP) and implications for terrestrial carbon sequestration. Using free-air CO(2) enrichment (FACE) technology, we exposed north-temperate forest communities to concentrations of CO(2) and O(3) predicted for the year 2050 for the first 7 yr of stand development. Site-specific allometric equations were applied to annual nondestructive growth measurements to estimate above- and below-ground biomass and NPP for each year of the experiment. Relative to the control, elevated CO(2) increased total biomass 25, 45 and 60% in the aspen, aspen-birch and aspen-maple communities, respectively. Tropospheric O(3) caused 23, 13 and 14% reductions in total biomass relative to the control in the respective communities. Combined fumigation resulted in total biomass response of -7.8, +8.4 and +24.3% relative to the control in the aspen, aspen-birch and aspen-sugar maple communities, respectively. These results indicate that exposure to even moderate levels of O(3) significantly reduce the capacity of NPP to respond to elevated CO(2) in some forests.
authors.affiliation: Ecosystem Science Center, School of Forest Resources and Environmental Science, Michigan Technological University, Houghton, Michigan 49931, USA. john_king@ncsu.edu
authors.forename: John S
authors.initials: JS
authors.lastname: King
authors.forename: Mark E
authors.initials: ME
authors.lastname: Kubiske
authors.forename: Kurt S
authors.initials: KS
authors.lastname: Pregitzer
authors.forename: George R
authors.initials: GR
authors.lastname: Hendrey
authors.forename: Evan P
authors.initials: EP
authors.lastname: McDonald
authors.forename: Christian P
authors.initials: CP
authors.lastname: Giardina
authors.forename: Vanessa S
authors.initials: VS
authors.lastname: Quinn
authors.forename: David F
authors.initials: DF
authors.lastname: Karnosky
mesh_terms: D031002:Acer / Q000187:drug effects / Q000254:growth & development*; D029662:Betula / Q000187:drug effects / Q000254:growth & development*; D018533:Biomass; D002244:Carbon / Q000378:metabolism; D002245:Carbon Dioxide / Q000494:pharmacology*; D010126:Ozone / Q000494:pharmacology*; D018515:Plant Leaves / Q000187:drug effects / Q000502:physiology; D032107:Populus / Q000187:drug effects / Q000254:growth & development*; D014934:Wood
chemical_list: D002245:Carbon Dioxide; D010126:Ozone; D002244:Carbon