Modelling long-term impacts of changes in climate, nitrogen deposition and ozone exposure on carbon sequestration of European forest ecosystems

摘要

We modelled the effects of past and expected future changes in climate (temperature, precipitation), CO_2 concentration, nitrogen deposition (N) and ozone (O_3) exposure (phytotoxic ozone dose, POD) on carbon (C) sequestration by European forest ecosystems for the period 1900-2050. Tree C sequestration was assessed by using empirical response functions, while soil C sequestration was simulated with the process-based model VSD, combined with the RothC model. We evaluated two empirical growth responses to N deposition (linear and non-linear) and two O_3 exposure relationships (linear function with total biomass or net annual increment). We further investigated an 'interactive model' with interactions between drivers and a 'multiplicative model', in which the combined effect is the product of individual drivers. A single deposition and climate scenario was used for the period 1900-2050. Contrary to expectations, growth observations at European level for the period 1950-2010 compared better with predictions by the multiplicative model than with the interactive model. This coincides with the fact that carbon responses in kg C ha~(-1) yr~(-1) per unit change in drivers, i.e. per ℃, ppm CO_2, kg N ha~(-1) yr~(-1) and mmol m~(-2) yr~(-1) POD.