Location: Adaptive Cropping Systems LaboratoryTitle: Comment on "Unexpected reversal of C3 versus C4 grass response to elevated CO2 during 20-year field experiment"
Submitted to: Science
Publication Type: Other
Publication Acceptance Date: 7/11/2018
Publication Date: 8/10/2018
Citation: Wolf, J.E., Ziska, L.H. 2018. Comment on "Unexpected reversal of C3 versus C4 grass response to elevated CO2 during 20-year field experiment". Science. 361:6402.
Technical Abstract: In the article "Unexpected reversal of C3 versus C4 grass response to elevated CO2 during a 20-year field experiment" (1), the authors explain that positive responses of biomass to elevated CO2 disappear in C3 grasses and appear in C4 grasses over twenty years. In the article and the associated 'Perspectives' coverage, "Plant responses to CO2 are a question of time" (2), the authors and commenters assert that these results "challenge the current C3-C4 eCO2 paradigm." Additional context should be made available to qualify this assertion. The pattern documented by Reich et al. can also be explained by considering the natural history of the experimental plants and soils, without challenging general expectations of C3 and C4 grass responses to elevated CO2 in the absence of other limitations.