CO2 response curves can be measured with a field-portable closed-loop photosynthesis system D. K. McDermitt, J. M. Norman, J. T. Davis, T. M. Ball, T. J. Arkebauer, J. M. Welles and S. R. RoernerAnn. For. Sci., 46 Supplement (1989) 416s-420sDOI: https://doi.org/10.1051/forest:19890593