Isoprene emission from terrestrial ecosystems in response to global change: minding the gap between models and observations.
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.
Monson
Russell K
RK
Department of Ecology and Evolutionary Biology, University of Colorado, Boulder, CO 80309, USA. russell.monson@colorado.edu
Trahan
Nicole
N
Rosenstiel
Todd N
TN
Veres
Patrick
P
Moore
David
D
Wilkinson
Michael
M
Norby
Richard J
RJ
Volder
Astrid
A
Tjoelker
Mark G
MG
Briske
David D
DD
Karnosky
David F
DF
Fall
Ray
R
D001272:Atmosphere; D002070:Butadienes; D017753:Ecosystem; D017752:Greenhouse Effect; D045782:Hemiterpenes; D008962:Models, Theoretical; D010420:Pentanes; D014197:Trees; D014481:United States
D002070:Butadienes; D045782:Hemiterpenes; D010420:Pentanes; C005059:isoprene