Historical development of flora and vegetation on Jadovnik Mt. in the western Bosnia

Abstract

Jadovnik Mt. in the Western Bosnia and its wider surroundings in paleogeographic sense have been the part of Illyria, which did not have contact with the eastern part of Balkan Peninsula until the Pleistocene, two million years ago. Geological composition of Jadovnik Mt. and its foothill in largest part was created in periods of Mesozoic: Triassic, Jurassic and Cretaceous. The oldest relic plants of the research area created in Paleogene, on isolated Illyria. During the larger part of Paleogene there was a warmer climate, which enabled development of polydominant communities, with complex structure and large number of species. On account of cooling, at about the end of Tertiary, tropical species became extinct and northern elements were expanding. Thanks to the southerly position, warmer climate and previous adaptation, the vegetation of Balkans in Pleistocene did not changed, but all altitudinal belts of vegetation descended for several hundred meters. Balkan Peninsula has become the refuge for the flora which retreated from north and central Europe, and during Interglacials again expanded to the north. Array of plant species on this area, included the area of Jadovnik Mt., exists from Tertiary until today. The considerable number colonized only after joining of Illyria with the continental Europe. Using pollen-diagram method, history of vegetation on large number of localities throughout Europe was revealed. For history of flora and vegetation on Jadovnik Mt. pollen-diagram from the locality of Male mrtvice (Livanjsko Polje, 20 km south-east from the foothill of Jadovnik Mt., elevation 700 m a.s.l.) is very indicative. It was analyzed by Gigov & Nikolić (1959). Analysis established that on this locality during Preboreal period there was domination of Pinus sp., while in Boreal Quercus sp. Atlantic period was characterized by mixed forest Alnus-Fagus-Quercus phase, Subboreal by Fagus- Pinus, and Subatlantic by Quercus-Fagus-Carpinus-Pinus forest phase. In Preboreal period the coniferous genera Pinus, Picea and Abies were distributed at least twice more than today on researched area. Beech was most frequent out of the broadleaved trees. Based on the results of pollen-analysis of more sites, we can hypothesize that in Boreal the belt of oaks was distributed on Jadovnik Mt. which reached the considerable elevations and that the highest belt of this mountain was built by fir and spruce. The middle altitudinal belt was occupied by pines and hornbeams. Based on the presence of pollen in the spectrum of locality Male mrtvice, in Atlantic period Jadovnik Mt. was covered by forest belt of alder, oaks and hornbeam, beech (on the mesophilous locations) and pine (on the dryer sites) and then in the middle belt of beech with fir, while in the highest zone belt of beech, fir and spruce.