Long-term dynamics of Oriental beech (Fagus orientalis Lipsky) stands in the Hyrcanian forests of northern Iran

Abstract

Although Oriental beech is the dominant and economically most important species in the Hyrcanian forests of northern Iran, little is known about its long-term dynamics and their drivers. To fill this gap, two small lake-mire complexes with mainly local pollen deposition signals and a larger peatland with presumably mainly regional pollen signals in the beech zone of the Hyrcanian region were compared using pollen analysis, AMS radiocarbon dating and ordination techniques. The pollen data confirm the long-term continuity of a regional mixed deciduous broadleaved forest cover dominated by beech-hornbeam stands with short intervals of co-dominating oak and, to a lesser extent, elm accompanied by lime, ash, Cappadocian maple and Persian ironwood. At the (extra)local scale, hydrological changes drove the development of Caucasian alder, velvet maple and wingnut. Except for the last 1–2 centuries, in which human intervention intensified, climate change was the main factor influencing forest structure and composition in the area. This study provides an important reference for ecological restoration of the unique broadleaved forests in Western Asia.