Spatial Decision Support Systems (SDSS) combine Decision Support Systems (DSS) and Geographical Information Systems (GIS) to support decision makers in managing complex spatial problems. Such problems are commonly evaluated based on multiple criteria, consist of a large number of decision alternatives, involve uncertainty in their decisions and have therefore been adopted to manage various complex environmental processes such as natural hazards and water resources. An SDSS must be able, in addition to providing requirements common to any DSS, to support the input and storage of spatial data and the application of spatial analysis methods and to build prediction models that can simulate dynamic spatial processes and evaluate the effect of different future scenarios for decision-making. To support farmers in efficient precision management of tree crops, a GIS-based SDSS is under construction within the framework of the '3D-Mosaic' project which aims at optimizing water consumption in tree plantations by employing precision agriculture methods. Tree plantation test sites in Turkey and in Germany are currently monitored for plant and fruit growth under different environmental conditions and irrigation regimes using an autonomous mobile sensing and image analysis platform. Data is collected using various sensors, on a variety of plant-related and site-related variables. The constructed 3D GIS database is currently analyzed for variability using spatial statistic methods to assess the spatiotemporal patterns of a-biotic and plant related data. Recognized patterns will be used to develop algorithms for deriving: (a) tree adapted management zones and (b) site-specific irrigation maps. These maps will serve as the basis for developing SDSS interface to support farmers in orchard management.