The concept of landscape units in general refer to coherent spatial areas that are characterized by a certain degree of homogeneity concerning certain properties like natural conditions (geology, geomorphology, soils and climate) and land use. A more analytical approach, with no preconceived geometrical objects, is the simple overlay of different thematic maps, in order to define features. Parallel characterization methods like the Matrix, Patch, and Corridor framework, although very useful in the description of the functional role of the geographical entities, are unable to differentiate the nature of the factors determining those entities. By the other hand, landscape metrics, defined as algorithms that quantify specific spatial characteristics of patches, classes of patches, or entire landscape mosaics, could be useful to define landscape units that have a common set of geometrical properties, referring to coherent spatial areas that are characterized by a certain degree of homogeneity concerning those properties.
Some authors conceived a landscape unit as a combination of the stable environmental factors (e.g., geology) with the circumstantial factors (land cover). The variables such as the property structure and human settlement are reflected largely in land use geometry.
In this study, the Centro region of Portugal was divided in 10 km x 10 km UTM grids. A set of landscape metrics was calculated for each grid representing the land use (COS’2007 - level 3). A cluster analysis was performed in order to define groups of grids that have the same geometrical proprieties. The validation of the results obtained with previously defined landscape units and potential vegetation mapping confirm the reliability of the present methodology
