Parameterizing the Kok Effect: How Light Inhibition of Respiration Affects Ecosystem Carbon Budget Predictions

Abstract

Models of the complex feedbacks between carbon storage by vegetation and climate often disregard the effects of light inhibition of plant respiration. Using the Ecosystem Demography 2 terrestrial biosphere model in conjunction with Net Ecosystem Exchange eddy covariance data collected in Alaska, we propose several parameterizations of the Kok effect and test them. The most successful parameterizations suggest high light threshold values and strong inhibition of light. Implementing these parameterizations in our model leads to faster predicted growth for the two stands of trees under consideration. This indicates the potential of the Kok effect to signicantly alter long term climate and biosphere predictions when included in terrestrial biosphere models.