Geographical Analysis of Upper-Alpine Rock-Scree Flora of Central And Eastern Caucasus

Species of plants, forming upper-alpine rock-scree vegetation of Central and Eastern Caucasus, have different habitats, in most cases exceeding the limits of the studied area. Analysing these habitats enables to discover the chorological nature of the researched flora, determine dominating geoelements, which provides the basis for, first, correcting the schemes of biogeographic zoning, as well as solving the issues, related with the history of flora. Upper-alpine rock-scree plants of Central and Eastern Caucasus belong to caucasian-holarctic-irano-turanian. The head part of the geographical range corresponds with the sequence of families Apiaceae – Cyperaceae – Poaceae, sequence of geni – Campanula – Carex – Ranunculus and Minuartia. It follows from the above said that the studied flora does not contain tertiary relicts, although ancient species, which may date as far back as the tertiary, exist. These include all ferns and gymnosperms, evergreen bush Rhododendron caucasicum, evergreen shrubs Vaccinium vitis-idaea, Empetrum caucasicum, Daphne glomerata, wintergreen subshrub Dryas caucasica. Also, there are no xerothermic relicts, as in highlands there are no arid areas where the remains of xerophiles could survive. In terms of xerothermic relicts, they can include only one species Cirsium cephalotes, transcaucasian-asiatic species, having within the researched region a relict area up the river Baksan.