Soil–diversity relationships in refugial endemic coniferous forests of the Balkan Peninsula

Abstract

Refugial coniferous forests of South-East Europe represent unique and poorly studied forest ecosystems. Shaped by contrasting maritime and continental climatic influences and complex orography, these forests support several endemic and relict tree species. We investigated soil and vegetation properties and their relationships in pure stands of Serbian spruce ( Picea omorika (Pančić) Purk.), Macedonian pine ( Pinus peuce Griseb.) and Bosnian pine ( Pinus heldreichii Christ.). Twelve sample plots covering a total area of 3.6 ha were established at three representative localities in Bosnia and Herzegovina (Veliki Stolac), Serbia (Beleg) and Montenegro (Zeletin). Soil profiles, phytocoenological records and forest inventory measurements were obtained, and soil samples from 5 -15 cm depth were analyzed for basic physicochemical properties. All investigated refugial forests developed on limestone and shallow Leptosols. Clear differences in soil properties, vegetation and forest diversity were observed among the studied species. High organic matter values, changes in the C/N ratio among habitats, and relationships among soil parameters were identified. Forest-layer cover was significantly associated with soil properties. Orographic gradients were related to soil properties, vegetation composition and forest diversity. The results indicate that soil properties and forest diversity in refugial endemic coniferous forests are shaped by the interaction of orographic conditions, tree species, stand structure and ground vegetation rather than by altitude or substrate alone. The findings provide an ecological basis for improving conservation and management approaches for these highly valuable and fragmented forest ecosystems.