The heterogeneity of landscapes – as a parameter of landscape structure – is connoted as the “quality or state of consisting of dissimilar elements, as with mixed habitats or cover types occurring on a landscape”. It is the “opposite of homogeneity, in which elements are the same” (Turner et al., 2003, 3).
As indices of landscape structure, landscape metrics can be used to describe the composition and spatial arrangement of a landscape. They can be applied at different levels to describe single landscape elements by such features as size, shape, number or for whole landscapes by describing the arrangement of landscape elements and the diversity of landscape. The reason for using these metrics in spatial analysis may be to record the structure of a landscape quantitatively on the basis of area, shape, edge lines, diversity and topology-descriptive mathematical ratios; to document for purposes of monitoring; or to make the relevant information available as input parameters for landscape ecological simulation models.
Overviews of the current discussions and the application of landscape metrics are given on the use of landscape metrics for landscape analysis with Geographic Information Systems (GIS) by Lang and Blaschke (2007), the application of landscape metrics in nature protection and landscape research by Blaschke (2000) and Uuemaa et al. (2009*), on existing landscape metrics and software by McGarigal et al. (2002) and Walz (2006), and on landscape pattern and landscape indicators by Bolliger et al. (2007*).
For a definition of biodiversity (or biological diversity), the Convention on Biological Diversity (1992) is often cited (United Nations, 1993): “For the purposes of this Convention …‘Biological diversity’ means the variability among living organisms from all sources including, inter alia, terrestrial, marine and other aquatic ecosystems and the ecological complexes of which they are part: this includes diversity within species, between species and of ecosystems.” Biodiversity thus comprises the fields of genetic diversity, species diversity (number of species in certain units of space) and diversity of habitats and ecosystems at the landscape level (see Blab et al., 1995*, 11, Figure 1*). Thereby, each level is dependent on each other. The dynamics of natural processes, such as the changing distribution patterns of species and habitats in space and over time, are also part of biological diversity (Blab et al., 1995*, 11). At each level of biodiversity, three fundamental characteristics of biodiversity can be considered: composition, structure and function (Noss, 1990; Waldhardt and Otte, 2000). Composition describes the individuality and variety of elements, such as land use units or species within a region. Structure, by contrast, refers to the arrangement or the construction of units, the distribution of elements and their relationship to one another. Function, finally, comprises all processes, such as demographic trends, cycles of material or disturbances (Lipp, 2009, 37). Especially at the landscape level, composition and structure can be described by landscape metrics.
Biodiversity depends on geo-diversity, i.e., the variety of natural conditions, such as relief, soil characteristics and local climate, but in cultural landscapes also on the land use. Geo-diversity, biodiversity and land use diversity as a whole can be called “landscape or eco-diversity” (Jedicke, 2001, 60). Today, the anthropogenic influence in most regions is very high. A clear distinction between natural and cultural landscapes is virtually impossible. For this reason, it is important not only to consider the natural areas or landscape elements, but also the influence of man, for example, by investigating land use and land use structure.