Modelling critical loads for the Solling spruce site

Critical loads were assessed with a steady-state soil model, a dynamic soil model, and an integrated forest-soil model, using data from the Solling spruce site. The critical loads of sulphur obtained with the dynamic and integrated models are close (within 30%) to the steady-state model calculations. For nitrogen, the spread in the model results is wider owing to the very different criteria (soil solution chemistry versus forest vitality) used for deriving the critical loads. The agreement lends confidence to the simplified critical-load calculations carried out on a European scale