Evaluating the impacts of climate variability and disturbance regimes on the historic carbon budget of a forest landscape

The regression of age-detrended variations in the simulated annual C fluxes to mean daily maximum air temperature over the peak growing season (July-September), during an undisturbed period from 1963 to 1984, indicated that summer temperature was the dominant climatic control on landscape-level C fluxes. Higher temperatures caused a decrease in gross primary productivity at almost twice the rate of increase in ecosystem respiration (i.e. 27 g C m−2 yr−1 C−1 versus 15.7 g C m−2 yr−1 C−1, respectively). A sensitivity analysis to evaluate the impacts of climate variability and disturbances showed that the relative effect of disturbance on carbon stocks was greater than the effect on carbon fluxes. Overall CO2 fertilization effects were minor. Disturbance type and severity, represented by the standard deviation in NBP, as described in the model, determined the magnitude of the simulated C losses to the atmosphere. This study enhances our understanding of the impacts of future climate change and forest management on landscape-level C dynamics in forests.