title: Isoprene emission from terrestrial ecosystems in response to global change: minding the gap between models and observations.
abstract: Coupled surface-atmosphere models are being used with increased frequency to make predictions of tropospheric chemistry on a 'future' earth characterized by a warmer climate and elevated atmospheric CO2 concentration. One of the key inputs to these models is the emission of isoprene from forest ecosystems. Most models in current use rely on a scheme by which global change is coupled to changes in terrestrial net primary productivity (NPP) which, in turn, is coupled to changes in the magnitude of isoprene emissions. In this study, we conducted measurements of isoprene emissions at three prominent global change experiments in the United States. Our results showed that growth in an atmosphere of elevated CO2 inhibited the emission of isoprene at levels that completely compensate for possible increases in emission due to increases in aboveground NPP. Exposure to a prolonged drought caused leaves to increase their isoprene emissions despite reductions in photosynthesis, and presumably NPP. Thus, the current generation of models intended to predict the response of isoprene emission to future global change probably contain large errors. A framework is offered as a foundation for constructing new isoprene emission models based on the responses of leaf biochemistry to future climate change and elevated atmospheric CO2 concentrations.
authors.affiliation: Department of Ecology and Evolutionary Biology, University of Colorado, Boulder, CO 80309, USA. russell.monson@colorado.edu
authors.forename: Russell K
authors.initials: RK
authors.lastname: Monson
authors.forename: Nicole
authors.initials: N
authors.lastname: Trahan
authors.forename: Todd N
authors.initials: TN
authors.lastname: Rosenstiel
authors.forename: Patrick
authors.initials: P
authors.lastname: Veres
authors.forename: David
authors.initials: D
authors.lastname: Moore
authors.forename: Michael
authors.initials: M
authors.lastname: Wilkinson
authors.forename: Richard J
authors.initials: RJ
authors.lastname: Norby
authors.forename: Astrid
authors.initials: A
authors.lastname: Volder
authors.forename: Mark G
authors.initials: MG
authors.lastname: Tjoelker
authors.forename: David D
authors.initials: DD
authors.lastname: Briske
authors.forename: David F
authors.initials: DF
authors.lastname: Karnosky
authors.forename: Ray
authors.initials: R
authors.lastname: Fall
mesh_terms: D001272:Atmosphere; D002070:Butadienes; D017753:Ecosystem; D017752:Greenhouse Effect; D045782:Hemiterpenes; D008962:Models, Theoretical; D010420:Pentanes; D014197:Trees; D014481:United States
chemical_list: D002070:Butadienes; D045782:Hemiterpenes; D010420:Pentanes; C005059:isoprene