Sprecher
Beschreibung
The spatially complex area of the Southern Caucasus is a unique laboratory to study the regional impact of global climatic changes on vegetation. Pollen archives from the Armenian Highlands and western Georgian lowlands reflect the diversity of landscapes as well as the regional differences of Early Pleistocene Glacial-Interglacial variability.
In southern Armenia, pollen data document a clear vegetation response on orbitally forced climatic changes with open vegetation during glacial as well as less pronounced interglacial phases, and the expansion of woody vegetation during and after very warm and humid interglacials. Furthermore, the age of the numerous macro floral assemblages could be constrained to the warm and more humid parts of the climatic phases, confirming the expansion of forests at that time. Still, diversity remains low in this overall dry environment.
In western Georgia, pollen data show no change in lowland vegetation despite some fluctuations in pollen assemblages. Climate remained warm and humid throughout the Early Pleistocene supporting broadleaved mixed beech forests. Accordingly, pollen richness and diversity decrease only slightly with time due to stepwise extirpation of thermophilus taxa during glacial phases while evenness remains high in the relatively stable environment. Here, the uplift of the Caucasus mountain range counteracted global climatic forcing.
This unique interplay of global climate, regional topography and tectonic effects led to favorable climatic conditions for the development of the Colchic vegetation refuge in western Georgia and the high biodiversity in the Caucasus in general.