Biotope Types of the Treeline of the Central Greater Caucasus

Abstract

Some characteristics (habitat, distribution, characteristic species, ecological importance, practical use and danger factors) are given of 17 typical treeline biotopes in the Kazbegi region, situated on the north-facing macro slope of the central part of the Main Watershed Range of the Greater Caucasus. The diversity of species composition is mainly due to peculiar structural properties of the vegetation of these biotopes, rather than ecological (altitude, moist or dry conditions,) and anthropogenic (grazing, haymaking) factors. The majority of the studied biotopes are referred to the II stage of hemeroby, but untouched shrub communities (dominated by Rhododendron caucasicum), elfin crookedstemmed birch forests (dominated by Betula litwinowii) and fragments of tall herbaceous vegetation should be referred to the I stage of hemeroby (natural and close to natural). Current global climate change will cause the most drastic changes in moist (tall herbaceous vegetation), snowline (humid broad-leaved meadows dominated by Trollius ranunculinus), broad-leaved mesophilous meadows (dominated by Anemone fasciculata), elfin crookedstemmed birch forest and scrub biotopes. The numerous biotopes are characterized by high sensitivity, which is caused by the following factors: landscape mainly devoid of forests, high degree of relief and, consequently, bare soil cover, low and unstable snow cover, frequent solifluction, etc. The following biotopes should be regarded as priority habitat types: tall herbaceous vegetation, scrub and elfin crooked-stemmed birch forest.