RECONSTRUCTIONS OF THE MID- AND LATE-HOLOCENE CLIMATIC CHANGES BASED ON POLLEN DATA FROM THE EASTERN BASIN OF LAKE SAKI (CRIMEA)
Twenty pollen zones have been established and they show multiple changes in the vegetational cover. Pollen spectra from the lowermost deposits represent a dry (Poaceae-Artemisia) steppe corresponding to the arid phase of the Late Atlantic. During the Subboreal period, there occurred an alteration of a typical grassland with xerophytic Artemisia-Poaceae steppe. The Subatlantic was marked by the shift from Artemisia-Poaceae communities to mesophytic Herbetum mixtum-Poaceae steppe. The human impact on the vegetational cover is firstly observed in the Early Subatlantic by the regular appearance of Cerealia and Juglans regia pollen.
Quantitative climate reconstructions have been carried out using two unimodal models (Birks, 1995): a weighted-averaging model with inverse deshrinking (WA) and a weighted averaging partial least squares model (WA-PLS). Mean annual precipitation, mean annual temperature, and mean July and January temperatures have been reconstructed. The prediction errors for two models range between 0.5 and 0.8°C for temperature reconstructions, and 7-13 mm for precipitation reconstructions. Reconstructed temperature anomalies reach up to 1°C and precipitation ones – up to 15 mm. Both qualitative and quantitative reconstructions show that, in general, warm phases are relatively dry and cool phases are relatively wet. The warm and cool phases are directly correlated with the transgressions and regressions of the Black Sea.