The terms zonal and azonal vegetation were introduced by Heinrich Walter (1954, 1979) in vegetation science and landscape ecology. Russian colleagues, especially soil scientists, used this terminology earlier.

‘Zonal’ refers to zonal regional climate and zonal sites with zonal soils. The zonal vegetation corresponds primarily to zonal regional climate.

‘Azonal’ refers to special edaphic conditions of water supply under the same regional zonal climate.

Azonality means too much humidity and/or water at the surface (e.g. lakes and ponds, streams, bogs and mires including seepage areas and flush). This implies much more variation in the vegetation depending on local factors, such as humidity.

The opposite also happens: too dry as occurs on weathered rock surfaces of outcrops or on lithosols. Epilithical communities have not been studied and only occasionally sampled. Also epiphytic communities on trees, shrubs and bamboos have not been considered.