Research approach Environmental management of the 'Green Heart of the Randstad' serves as an example. Figure 1 shows the predicted quality of nature in this region as a result of a low and a high NO x management alternative. The maps use 819 grids classified into three classes. A routine has been developed to generate the classification that maximises the difference between the maps. This question is better addressed using a simple map combination such as the difference map presented in Figure 2.
Size is an important issue in nature management.
Not only the total area is relevant but also the distribution of this area. Large connected areas are preferred to a dispersed pattern. Figure 3 shows nature areas with a minimum size of 25 km 2 in black and the smaller areas in grey. Although the total nature area is almost the same for both alternatives, Figure 3 shows clear differences if the distribution of the areas is considered. Other map transformations included in the evaluation module are filtering, fragmentation and dominance maps.