Phytosociological analysis of the lowland forests of peri-Pannonian Bosnia (SE Europe)

Peri-Pannonian Bosnia was a forest-dominated landscape in the past. However, it has experienced extensive and continuous negative anthropogenic influence for over 200 years resulting in significant reduction and fragmentation of forest area. The remaining forests are not sufficiently studied, and little is known about their floristic composition, ecology and classification. In order to study the lowland forest from this area, Lijevče Polje (central part of the area) was chosen because of the relatively large patches of preserved forest. Phytosociological research was carried out from 2016 to 2023 using the Braun-Blanquet method, resulting in the compilation of a dataset consisting of 73 relevés of forest vegetation. These relevés were classified using TWINSPAN into 15 units and afterwards merged into 8 groups, representing associations that were floristically and ecologically analyzed. One group, encompassing swamp alder forest, was identified as Carici elongatae-Alnetum glutinosae. Two groups represented forests with yearly fluctuations in soil moisture ranging from water-saturated to very dry soils. One of those groups, characterized by extreme soil moisture fluctuation, was attributed to Pseudostellario-Quercetum roboris, while the other group, with mild soil moisture fluctuation, was attributed to Genisto elatae-Quercetum roboris. Three groups were documented along streams and were attributed to: Salicetum albae, occupying the lowest river terraces; Fraxino pannonicae-Ulmetum glabrae, occurring on elevated river terraces; and Stellario nemorum-Alnetum glutinosae, confined to smaller streams. Two groups positioned in areas outside the flood zone were identified: Convallario- Carpinetum, occurring on old river terraces, and Stellario-Carpinetum, found on mountain foothills. Ellenberg indicator values were used to detect significant factors that shape the floristic composition of the analyzed plant communities. The distance from the nearest river and elevation were also useful in understanding ecological and topographic attributes of the communities. The driest and most wide- spread communities are those dominated by Carpinus betulus and Quercus robur. Riparian forests are confined to riverbanks while swamp forests are found in microdepressions that were not meliorated in the past. These findings contribute to the phytosociological understanding and classification of forest vegetation in peri-Pannonian Bosnia, providing a basis for future conservation efforts and classification.