In order to obtain ecological guidelines for the planning of nature conservation and nature design in the general framework of regional planning, landscape ecological investigations have been set up in the Kromme Rijn area (Fig.1). The main basical documents are the soil map and the vegetation map. Some backgrounds of these maps are described. Illustrated by map fragments (Fig.2, 3 and 4), soil conditions and the vegetation of the area are pictured briefly. By comparison of soil and vegetation map it was first tried to distinguish ecological units. These are grouped as micro-, meso- and macro-units. The first are soil-vegetation units developed under a given management. The second are areas with more or less homogeneous soil conditions but a complex vegetation pattern as a result of different management (Fig.5). The macro-units are characteristic patterns of meso-units. Next diversity in landscape is studied for the purpose of suitability evaluation for nature conservation and nature design. The basic assumption is that diversity, especially when developed as a result of longlasting differentiation processes, is a criterion for the irreplaceable character of an area. And this determines the importance for conservation of actual and potential richness of biocoenoses. From the vegetation map a map unit diversity map and a structure diversity map are derived. By combination of the last two maps the actual differentiation values are mapped. Thus the importance of areas for nature conservation is made visible (Fig.6). From the soil map a map unit diversity map and a main differentiating gradient map are derived. By combination of these two maps the potential differentiation values are mapped. Thus the importance of areas for nature design is made visible (Fig.7). In this way diversity is used to evaluate areas for nature conservation and nature design functions. The unities, however, may serve as the ecological basis for proper management, once a certain function is given to the areas concerned. Nature conservation and nature design, of all functions are most bound to existing site conditions and therefore should be considered the hard core of regional planning. As the irreplaceable character of a given area determines its importance for these two functions, the differentiation value maps can be translated into a vulnerability map, indicating the risk for irreparable damage in case of radical changes like town and road building, etc. (Fig.8). Spatial arrangement of functions in landscape can be completed by further survey. Ecological suitability maps for recreation, agriculture, etc. should play a role in this procedure. Once it has been decided which functions are given to different parts of landscape, the problem of external conditions such as drainage systems, quality of water and air, etc. can be studied more profoundly. In the discussion only some major problems are dealt with. First the comparability of soil and vegetation maps is discussed. Next some remarks are made on the ecosystem character of the micro-, meso- and macro-units described. Finally some comments are given on the problems related to diversity in landscape.