On the Holocene vegetation history of the Central Rila Mountains, Bulgaria: The palaeoecological record of peat bog Vodniza (2113Â m)

Information on the Holocene vegetation history of the Central Rila Mountains for the last 10,000 years was obtained by means of pollen and fossil stomata analyses of a 500 cm core retrieved from peat bog Vodniza (2113 m a.s.l.), and supported by radiocarbon chronology. The early Holocene afforestation started with an initial Betula phase with stands of Juniperus and Pinus which occupied barren soils (10,000-8300 cal. yrs. BP) while deciduous oak forests with abundant Tilia, Ulmus, Acer, and later on Corylus, spread at lower elevations. During the Holocene climatic optimum (8300-6000 cal. yrs. BP) the conifers Pinus (Pinus sylvestris, Pinus mugo, Pinus peuce) and Abies expanded at the expense of the birch and oak forests. The tree line was running above 2100 m comparable to the present-day situation and started to descend after ca. 3200 cal. yrs. BP mostly due to human impact. The last tree which penetrated into the coniferous belt after 3400 cal. yrs. BP and reached altitudes of 2000-2100 m, confirmed by the find of fossil stomata, was Picea abies. Its maximal distribution was achieved between 2250 and 1100 cal. yrs. BP, alongside with some enlargement of beech communities. The first indications of stock-breeding and other human activities in the Central Rila Mountains were recorded since 3400-3200 cal. yrs. BP (Late Bronze Age). The vegetation reconstruction during the Holocene followed a pattern coherent with the information from the Northern Pirin and partly from the Western Rhodopes Mountains. The palaeoecological evidence from the Rila Mountains could be compared in broad lines with the high quality data obtained from the Romanian Carpathians by the application of multi-proxy research approach.