The problem of biodiversity has lately been the centre ofintensive attention of biologists and ecologists. However its essence and research methodology are not clear enough yet.

We understand biodiversity as the presence of a certain range of biosystems, biological species, their populations, genotypes, biotypes, ecotypes, phenotypes etc. within the ecosystems of various taxonomic levels.

Methodology of biodiversity research incorporates the choice of the level of biodiversity assessment, the assessed elements of biodiversity and criteria for its assessment.

The possible levels of biodiversity assessment are biosphere, vegetation (climatic) zone, vegetation (climatic) subzone, vegetation (climatic) area (sector), type of geographical landscape, biocenosis type, fragment types.

The possible elements of biodiversity are plant formations, biocenoses (zoocenoses and hytocenoses), synusias, consortia, biological species, their populations, genotypes and the corresponding biotypes, ecotypes and phenotypes. The listed elements of biodiversity are divided into biosocial (formations, biocenoses, synusias, consortia) and genetic ones (biological species, populations, genotypes etc.).

The possible criteria for biodiversity assessment are the age, composition, productivity, mosaic nature, occurrence, position in the succession series and other characteristics pertinent to various biodiversity elements.

The ideal model of biodiversity is climax biosystems. If these are not available a system of standards has to be developed for biosystems with various positions in the succession series.