This model has three components: taxonomy, a study of geographical units of plant communities, and the classification of plant associations. Each component involves classification, typification and consideration of spatial factors. Yurtsev (1982, 1991, 1992) determined three hierarchical levels of taxonomic biodiversity: populational-genetic, specific, and super-specific, of which specific is the basic level. The species composition of south-eastern Ukraine is the sum of all the local populations. These populations are the ground units of the model. Plant diversity is the result of associations of organisms within areas defined by plant community classifications (Takhtadjan, 1978; Yurtsev, 1992). The term "flora-isolate" has been proposed as a unit for floristic analysis of disturbed areas (Burda, 1991). The basic unit of plant communities is the ecotope, which may be defined as a locality containing several species or species associations. The classification used in our model is based on dominant species (Shelyag-Sosonko, et al., 1991). Plants evolve within the same landscape as their communities, so ecotope classification must take into account physico-geographic or landscape land division. South-eastern Ukraine may be divided into four physico-geographic regions, in which 5 classes of ecotopes occur. These contain 26 main ecotopes ("macroecotopes") which are all natural. Three further "macroecotopes" can be recognized, which represent urban, industrial and other disturbed ecosystems which have no natural equivalents. Recording the different plant communities themselves is also very important in diversity research. We have distinguished 9 categories of plant community in the region. The model has been tested in the "Sviati Hory" national natural park and in cities of the region (Burda, 1996; Burda, 1997; Burda, Ostapko, Glukhov & Shpileva, 1988).