Tropospheric O3 moderates responses of temperate hardwood forests to elevated CO2:: a synthesis of molecular to ecosystem results from the Aspen FACE project uri icon

abstract

  • Summary The impacts of elevated atmospheric CO2 and/or O3 have been examined over 4years using an openair exposure system in an aggrading northern temperate forest containing two different functional groups (the indeterminate, pioneer, O3sensitive species Trembling Aspen, Populus tremuloides and Paper Birch, Betula papyrifera, and the determinate, late successional, O3tolerant species Sugar Maple, Acer saccharum). The responses to these interacting greenhouse gases have been remarkably consistent in pure Aspen stands and in mixed Aspen/Birch and Aspen/Maple stands, from leaf to ecosystem level, for O3tolerant as well as O3sensitive genotypes and across various trophic levels. These two gases act in opposing ways, and even at low concentrations (15ambient, with ambient averaging 3436nLL1 during the summer daylight hours), O3 offsets or moderates the responses induced by elevated CO2. After 3years of exposure to 560molmol1 CO2, the aboveground volume of Aspen stands was 40% above those grown at ambient CO2, and there was no indication of a diminishing growth trend. In contrast, O3 at 15ambient completely offset the growth enhancement by CO2, both for O3sensitive and O3tolerant clones. Implications of this finding for carbon sequestration, plantations to reduce excess CO2, and global models of forest productivity and climate change are presented.

published proceedings

  • FUNCTIONAL ECOLOGY

altmetric score

  • 6

author list (cited authors)

  • Karnosky, D. F., Zak, D. R., Pregitzer, K. S., Awmack, C. S., Bockheim, J. G., Dickson, R. E., ... Isebrands, J. G.

citation count

  • 266

complete list of authors

  • Karnosky, DF||Zak, DR||Pregitzer, KS||Awmack, CS||Bockheim, JG||Dickson, RE||Hendrey, GR||Host, GE||King, JS||Kopper, BJ||Kruger, EL||Kubiske, ME||Lindroth, RL||Mattson, WJ||Mcdonald, EP||Noormets, A||Oksanen, E||Parsons, WFJ||Percy, KE||Podila, GK||Riemenschneider, DE||Sharma, P||Thakur, R||Sôber, A||Sôber, J||Jones, WS||Anttonen, S||Vapaavuori, E||Mankovska, B||Heilman, W||Isebrands, JG

publisher