Desert Ephemeral Synusia As an Indicator for Archeological Sites

— A vegetation survey of three model sites has been conducted on the Emdy limestone plateau in the Mangyshlak middle desert subzone on the eastern shore of the Caspian Sea (Western Kazakhstan). The main goal was to find indicator species in vegetation composition which reflect ancient anthropogenic influence from about 1500 years ago. The model sites are situated in comparable ecological conditions and differ only by the type and time of anthropogenic influence. One is located in the area of an ancient settlement from the 3rd to 5th centuries, the second is in an area that may have been used for agriculture, and the third is a control without hardly any anthropogenic influence. It is found that four main synusia can be determined in the plant community structure. The most diverse synusia of the desert ephemeras contains 61% of the plant species pool and may be considered an indicator of former anthropogenic activity. There were no specific plants connected with past agriculture on the second site. Considering this fact, together with general ecological conditions of the site, it was concluded that there had been no agriculture on this site. It is shown that different ephemeral species react to microhabitat characteristics such as humidity, insolation, salinization, and soil bioturbations. All ephemeral species can be divided into true and induced ephemera. The latter group consists of widespread ruderal annual mesophytes ( Buglossoides arvensis and Descurainia sophia ). These species appear in places of long and intense anthropogenic pressure and are able to persist in plant communities at least up to 1500 years after the end of anthropogenic pressure.