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Palynological record of vegetation changes on the Eastern Adriatic Coast during the Holocene (Vrana and Baćina lakes)

Two sediment cores, from Lake Vrana (11 m) and Lake Crniševo, Baćina Lakes (8, 5 m), on the eastern Adriatic coast were analyzed using palynological and geochemical approach to detect environmental changes during the Holocene (Ilijanić, N. & Miko, S., 2015a ; Miko, S. & Ilijanić, N. ; 2015b). In the area of Lake Vrana near Biograd, the vegetation changes can be tracked from mixed forests and steppe vegetation from the Pleistocene through mixed oak and beech forest of older Holocene to an oak forest and finally to degradation stages of pine forest (macchia). During the Pleistocene in the area of today's Lake Vrana existed shallow depressions that are probably flooded during the interstadials when glaciers were melted. Water streams were formed, behind which puddle and pond were left. At the beginning of the Holocene precipitation was higher, which lead to gradually transition of the puddle and pond into the shallow lake. Due to the surface water runoff, stratification of the water column occurred resulting in anoxic conditions in the lower part of the lake. Then follows the period of the relatively deeper lake with dominant endogenic calcite precipitation and occasional runoff transports of terrigenous materials to the lake. Finally, the shallowing and fluctuation of lake water level occurred. In the Lake Crniševo, Baćina Lakes, we can observe vegetation development from mixed forests in moderately warm humid climate at the end of Pleistocene to Mediterranean vegetation. There are nine zones and nine subzones that match the changes in climate, vegetation, and trophicity. Samples of the oldest zone were deposited at a time of rapid meltwater pulses (MWP-1B) before 11.3 on cal BP in a hypertrophic shallow lake. Hypertrophic conditions also existed at the time of the next zone which is simultaneous with the precipitation of sapropel S1a 10.8-8.8 cal BP at the beginning of the Holocene. Deposition at the time of the following zone was in the proximal part of the mesotrophic lake. After that, the lake passes from the mesotrophic to the oligotrophic. The warming of climate and decrease of precipitation occurs. The following zone is divided into 6 subzones in which the humid and drought periods alternate (as well as a secondary succession of vegetation changes due to the forest clearing). Forest is being recovered some 1800 years ago, ie 200 AD. It is followed by an increased proportion of algae and grasses corresponding to the Medieval Warm Period, MWP (10th to 14th centuries) when the lake passes again from mesotrophic to eutrophic. In both lakes, the depth fluctuations and changes in vegetation occurred: from mixed forests in moderately warm humid climate at the end of Pleistocene to Mediterranean vegetation. As well, in both lakes, anthropogenic intervention in the lake system that significantly changed the conditions is detected.

palynology, Holocene, vegetation changes, Eastern Adriatic coast

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