Evaluation of a process-based ecosystem model for long-term biomass and stand development of Eucalyptus globulus plantations

Versatile process-oriented ecosystem models are discussed as promising tools for the analyses of ecosystem services beyond wood yield, such as catchment water yield, sequestration of carbon and greenhouse gas balances. However, long-term yield simulation is often regarded as a weakness of such versatile models. In this context, we present a multiple response evaluation of the modular, process-based forest growth model MoBiLE-PDT based on mensurational data from 38 permanent sample plots in commercial Eucalyptus globulus plantations in Australia followed from establishment to 8 years of stand age. MoBiLE-PDT is based on the PnET-N-DNDC model and considers nitrogen availability and drought stress dynamically in dependence on tree and stand properties as well as on climate and deposition. New tree dimensions are calculated directly from carbon allocated to sapwood and mortality is derived from stand density. Towards the end of the rotation, model efficiency E was 0.58 for stand volume (m(3) ha(-1)) and 0.54 for aboveground biomass (t C ha(-1)). In a comparison with similar forest growth models evaluated against the same data only one had a better model efficiency, whereas MoBiLE-PDT was the most versatile model for the analyses of ecosystem services. Due to its modular structure, further model extensions for more ecological applications are easily possible.