The insular distribution of beech forests in Romania – reminiscent of the glacial period induced by genetic and ecological plasticity

We attempt to explain the presence of the genus Fagus outside its usual climate range. We provide information regarding the evolution of beech wooded areas in the context of climate change, as well as on the morphological variability and the genetic and ecological plasticity.

In Romania, five study zones were selected that were found to be in extra range, with each area having 1–3 plots. The following parameters were identified for each area: number of the plots, surface of each plot, altitude, exposure, soil type, participation of beech in the composition of the forest, average age, average diameter measured at arm height (HDB, average height, and flora type. The climatic and bioclimatic indices were computed along with indices that describe particularities of Fagus species based on air temperature and precipitation data for the period 1901–2020. All 17 plots present in 5 mature forests are located at an altitude of less than 250 m above sea level. The average age of the beech is over 100 years, the oldest being about 170 years. The structure of the forests is the result of the pedo-climatic conditions. In the context of climate change, as well as the ecological plasticity, the morphological variability of species in the genus Fagus offers this genus the opportunity to adapt to new pedo-climatic conditions and to expand the range of some thermophilic beech species.