Past, present and future distributions of Oriental beech (Fagus orientalis) under climate change projections

Abstract

Species distribution models can help predicting range shifts under climate change. The aim of this study is to investigate the late Quaternary distribution of Oriental beech (Fagus orientalis) and to project future distribution ranges under different climate change scenarios using a combined palaeobotanical, phylogeographic, and modelling approach. Five species distribution modelling algorithms under the R-package `biomod2`were applied to occurrence data of Fagus orientalis to predict distributions under present, past (Last Glacial Maximum, 21 ka, Mid-Holocene, 6 ka), and future climatic conditions with different scenarios obtained from MIROC-ESM and CCSM4 global climate models. Distribution models were compared to palaeobotanical and phylogeographic evidence. Pollen data indicate northern Turkey and the western Caucasus as refugia for Oriental beech during the Last Glacial Maximum. Although pollen records are missing, molecular data point to Last Glacial Maximum refugia in northern Iran. For the mid-Holocene, pollen data support the presence of beech in the study region. Species distribution models predicted present and Last Glacial Maximum distribution of Fagus orientalis moderately well yet underestimated mid-Holocene ranges. Future projections under various climate scenarios indicate northern Iran and the Caucasus region as major refugia for Oriental beech. Combining palaeobotanical, phylogeographic and modelling approaches is useful when making projections about distributions of plants. Palaeobotanical and molecular evidence reject some of the model projections. Nevertheless, the projected range reduction in the Caucasus region and northern Iran highlights their importance as long-term refugia, possibly related to higher humidity, stronger environmental and climatic heterogeneity and strong vertical zonation of the forest vegetation.

5S-IGS rDNA in wind-pollinated trees (FagusL.) encapsulates 55 million years of reticulate evolution and hybrid origins of modern species

“…Beech forests persisted throughout the entire Neogene in this area (and in Caucasus as well) although experiencing severe bottlenecks (Shatilova et. al., 2011;Dagtekin et al, 2020). The sharing of rare variants is consistent with this scenario as they link isolated populations and otherwise distinct species to a once common gene pool (e.g.…”

The evolutionary heritage and ecological uniqueness of Scots pine in the Caucasus ecoregion is at risk of climate changes

“…Recently, the Pontic Mts. were defined as the probable refugial area for Fagus orientalis 61 . Palaeoenvironmental, pollen and genetic data concurrently point to the Pontic Mts.-Adjara as part of the wider refugial area defined for the Caucasian biota in areas surrounding the coasts of the Black Sea 20,62-64 .…”

Differentiation of ecological niches of the forest-forming species in the Caucasus

“…Broad-leaved forests of Fagus orientalis Lipsky covers the Greater and Lesser Caucasus, Crimea, Turkey, Northern Iran, Bulgaria, Greece, and Syria up to 2100 m above sea level [44,45]. The refuge for Fagus orientalis during the Last Glacial Maximum was Northern Turkey and the Western Caucasus, as well as Northern Iran [46]. A drier climate and higher temperatures against the background of climate change will probably limit the spread of this species in the future [46].…”

“…The refuge for Fagus orientalis during the Last Glacial Maximum was Northern Turkey and the Western Caucasus, as well as Northern Iran [46]. A drier climate and higher temperatures against the background of climate change will probably limit the spread of this species in the future [46].…”

“…According to Akatov et al [24], the range of suitable ecological conditions for Abies nordmanniana includes precipitation from 700 to 2500 mm and air moisture in the range of 70-80%. According to the modeling of Fagus orientalis range in Turkey [46], a drier climate and higher temperatures were limited for the species distribution. Modeling the potential distribution of Carpinus betulus in Anatolia and its surroundings using the Worldclim dataset also showed that the potential distribution of the species was strongly influenced by humidity-related variable (BIO18, Precipitation of Warmest Quarter) [47].…”