Long-term vegetation dynamics along altitudinal and longitudinal gradients in the Hyrcanian forest region (northern Iran) and the role of climate, sea level change, fire and anthropogenic impacts during the late Quaternary

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The Hyrcanian forests of Iran occurs in a 820 km long narrow belt on the northern slopes of Alborz and Talysh Mountains and occupies 6% of the area in Iran. This small belt hosts 3234 plant species including ca. 500 endemic plants and accounts for 44% of plant diversity. Along with the forests of northern Anatolia, Hyrcanian forests constitute the most important refugia and the last relicts of broad-leaved deciduous forests that covered the temperate zones of the northern hemisphere before the Quaternary. Hosting many remnants of the Arcto-Tertiary and Indo-Malaysian flora, the area is considered as a centre of biodiversity with global importance. Today, the original vegetation is distributed in altitudinal zones from the coast to the Alborz and Talysh highlands. Since the area is restricted by the Caspian Sea (CS) to the north and highlands to the south, the upper forest line and coastal vegetation have been subjected to pronounced changes due to temperature fluctuations and changes in the rainfall regime and CS sea level changes respectively, in space and time. In addition, anthropogenic forces have extensively modified the vegetation in the last centuries. Occurring in such changeable environmental conditions, investigating the Hyrcanian environmental history including vegetation, plant diversity, climate, fire, human impact and sea level change are of crucial importance. So far only a few palaeoecological records are reported from the Hyrcanian region. The Gilan province is the least studied province and is of high importance because: i) Gilan with extensive forests and wetlands is an appropriate area to carry out palaeoecological studies, ii) Gilan is the corridor that connects the isolated southern coast of the CS to western Eurasia and its vegetation history can provide new insights into the refugium hypothesis for the west Eurasian temperate deciduous forest, iii) Gilan is the wettest among the Hyrcanian provinces and its palaeoecology allow the comparison on an east-western precipitation gradient during the past, iv) Gilan is home of the most ancient known human settlements in Iran and v) has the largest remnant of coastal fluvial forest. This project will apply innovative multi-proxy studies (pollen, spores, charcoal, geochemical analysis, and others) of sediment cores and innovative (DNA meta-barcoding) modern pollen rain study on altitudinal gradients to investigate the environmental history of Gilan. Furthermore, a comparison between environmental history of eastern and western Hyrcanian region will be possible. This study will also provide background information for conservation and management of this centre of biodiversity and the results are of high importance for such as nature conservation, forest and rangeland management, agriculture, archaeology and sustainable development.