Vegetation and climate reconstruction based on pollen and microbial records derived from burial mounds soil in Tuva Republic, Central Asia

摘要

Beloe Ozero-3 Scythian tomb containing four burial mounds dated by the Liquid Scintillation Counting C-14 dating on the construction woods between 2560 +/- 115 to 2430 +/- 65 a BP is a very important archaeological site in the Turan-Uyuk Basin of the Tuva Republic, Russia. However, with large uncertainties of the dates, the sequence of the mound constructions and their paleoenvironmental conditions are unclear. Here we present the results of pollen assemblages from the soils buried under the mounds and surrounding areas to compare with well AMS C-14 dated pollen diagram of Lugovoe Mire in the same region. The comparisons allow us to conclude that (1) The four mounds were constructed in different environmental conditions at different time. (2) Mound 2 was constructed the first, Mound 3 was the second, Mound 1 was the third and Mound 4 was the last (3) Before the construction of tomb Beloe Ozero-3, the climatic conditions were relatively humid that promoted agriculture practice. (4) During construction of the first mound (Mound No2) the climatic conditions were close to modern. Pine (Pinus sylvestris) and Siberian cedar (Pinus sibirica) forests might have grown on the mountains surrounding the Turan-Uyuk basin from the north. 5) The climate during the construction of second mound (Mound 3) became more arid and agricultural field was abandoned. (6) During construction of the third by order mound (Mound 1) the climate was more arid than modern. Increase of anthropogenic pressure on landscape could be observed in pollen data of the last constructed mounds (Mound 1 and Mound 4). It is possible that drying climate caused gradual decline of Scythian culture. Comparisons with pollen spectra from the burial mound Arzhan-2, Beloe Lake-2, Tere-Khol Lake and Lugovoe Mire, it seems that the construction of Beloe Ozero-3 tomb took place during the period of semiarid climate close to modern but with more strong arid condition. This assumption is also confirmed by microbiological data from the buried soils. With the newly AMS C-14 dated pollen diagram of Lugovoe Mire, we will build up more precise pollen chronology in the study area.