This paper introduces a new way of using GIS to support decision making in the planning process and to develop regional guidelines. The method of `multicriteria optimization' helps new methodological standards to be established for integrating the various results of functional landscape ecology assessments of the type usually carried out in ecological planning, and enables the overall comparison of competing aims. This technique allows different aims in a geographical region to be quantified and takes into account different weightings of scenarios. Different functional assessments (soil erosion hazards caused by water flow, groundwater regeneration, water discharge regulation) and an assessment of the agricultural production function were carried out using GIS for a test site measuring 48 km² in a glacial end moraine area to the north of Leipzig (Saxony, Germany). The results were presented in the form of ordinal assessment classes which express tendencies. On the basis of these assessment results, aims for the calculation of an optimal land-use pattern were defined and weighted in different scenarios. Multicriteria optimization calculates optimal compromises with regard to these aims which can be measured and compared with goal function values. Although the method cannot replace decision making by the planner, which is often difficult and can generally not be quantitatively verified, it can help to make the planning process more objective.