Marginal/peripheral populations of forest tree species and their conservation status: report for Continental region

The report describes the geographical and ecological characteristics of the European continental region, which is the area that covers most of Central and Eastern Europe. Forest ecosystems and vegetational aspects, with particular emphasis to forest species growing at the edge of their distribution range, are also considered

Phylogeny of beech in western Eurasia as inferred by approximate Bayesian computation

The Fagus sylvatica L. species complex in Europe and Western Asia comprises two commonly recognized subspecies, F. sylvatica subsp. sylvatica [= F. sylvatica sensu stricto (s. str.)] and F. sylvatica subsp. orientalis (= F. orientalis), and two putatively hybridogenous or intermediate taxa, “F. moesiaca” and “F. taurica”. The present study aimed to examine the demographic history of this species complex using 12 allelic loci of nine allozymes scored in 279 beech populations in western Eurasia. Three sets of phylogenetic scenarios were tested by approximate Bayesian computation: one dealing with the divergence of subspecies and/or regional populations within the whole taxonomical complex, and two others focusing on the potential hybrid origin of “F. moesiaca” and “F. taurica”. The best-supported scenario within the first set placed the time of divergence of regional populations of F. orientalis in the Early Pleistocene (1.18–1.87 My BP). According to this scenario, the Iranian population was the ancestral lineage, whereas F. sylvatica s. str. was the lineage that diverged most recently. “Fagus taurica” was found to have originated from hybridization between the Caucasian population of F. orientalis and F. sylvatica s. str. at 144 ky BP. In contrast, there was no evidence of a hybrid origin of “F. moesiaca”. The best-supported scenario suggested that the Balkan lineage is a part of F. sylvatica s. str., which diverged early from F. orientalis in Asia Minor (817 ky BP), while both the Italian and Central-European lineages diverged from the Balkan one later, at the beginning of the last (Weichselian) glacial period

Are there hybrid zones in Fagus sylvatica L. sensu lato?

The complex of beech taxa in western Eurasia (Fagus sylvatica L. s.l.) represents one of the most widespread broad-leaved trees in the temperate forests of the northern hemisphere. Two subspecies are generally recognized, F. sylvatica ssp. sylvatica in Europe and F. sylvatica ssp. orientalis in southwestern Asia, but several strongly differentiated regional populations were identified within this complex. To reveal geographical and genomic patterns of hybridization and introgression, genetic variation at 6789 single-nucleotide polymorphisms (SNP) resulting from ddRAD sequencing was studied in 288 specimens representing 207 populations distributed across the whole range. Two clusters resulting from a Bayesian analysis of population Structure well coincided with the subspecies, while increasing the number of clusters allowed to distinguish divergent lineages within subspecies. Two zones of potential hybridization between such lineages were analyzed: western Balkans at the contact of both subspecies and the Alpine area at the contact of populations coming from different glacial refugia. Geographical distribution of hybrid indices in the Balkan hybrid zone indicates asymmetric gene flow preferentially directed from F. orientalis to F. sylvatica. Eight SNPs showed a significant shift of genomic cline centers, seven of them toward excess F. orientalis ancestry, suggesting that introgression irregularly affects different regions of the beech genome. On the other hand, no genomic cline outliers were found in the Alpine hybrid zone. Implications for assisted gene flow are shortly discussed

The Role of Provenance for the Projected Growth of Juvenile European Beech under Climate Change

European beech is one of the most common tree species in Europe and is generally suggested to play even more of a prominent role in forestry in the future. It seems to have the potential to partially replace Norway spruce, as it is less sensitive to expected warmer and drier conditions. It is, however, not well known in which regions these new plantings would be particularly favourable and if specific provenances may be better adapted to the new conditions than others. Therefore, we estimated the potential early height growth under climate conditions in 2040–2060 for 20 beech provenances across a region covering the Czech Republic and Slovakia. This Central European region is expected to experience considerably drier and warmer conditions in the future. For this exercise, we implemented a new neural network model developed from height growth information obtained from the open-access BeechCOSTe52 database. The simulations are driven by past and future climate data obtained from the WorldClim database of historical climate data and future climate projections. Simulations revealed that provenances originating from drier regions performed on average significantly better than those from regions with good water supply. Moreover, provenances originating from drier regions had a particularly large advantage in the relatively arid regions of Central Czechia and Southern Slovakia. We can also confirm that all provenances showed a high phenotypic plasticity of height growth across the whole investigated region

Spatial structure of a natural mixed topodeme of subalpine Sorbus taxa

Spatial distribution and genetic variation of a population of Sorbus chamaemespilus (L.) Crantz and putative hybrids between S. chamaemespilus, S. aria and S. aucuparia growing in the nature reserve Skalnä Alpa (central Slovakia) were studied. The analysis of spatial patterns using Ripley's K-function revealed a significant clustering of the adults of both S. chamaemespilus and hybrid taxa at distances up to ~15 m and a strong affinity between both taxonomical groups, indicating similar ecological requirements. Bivariate point-pattern analysis considering cardinal direction showed that juvenile individuals of S. chamaemespilus are clustered around the adults up to the distance of ~2 m, whereas in hybrid taxa with larger and more dense crowns, juveniles are clustered at distances more than ~3 m from the adults. The analysis of genetic variation in a subset of adult shrubs using 4 nuclear microsatellite loci revealed that unlike expected, there was no variation in S. chamaemespilus but several genotypes were found in the group of hybrid taxa. Implications for the reproduction system and conservation of the investigated taxa are discussed

Genetic variability of pedunculate oak (Quercus robur L.) at the Mediterranean margin of the distribution range

In Bosnia and Herzegovina, pedunculate oak (Quercus robur L.) occurs at the southern margin of its distribution range, close to the glacial refugia of this species. To assess the patterns of genetic diversity distribution at the rear edge of the Holocene colonization, we studied genetic variation in 20 pedunculate oak populations using 14 allozyme loci. Despite considerable differences among populations, neither the numbers of alleles nor genetic diversity showed any geographical trend within the studied area, although small isolated populations showed generally lower allelic richness. The Bayesian analysis of population structure indicated a kind of geographical pattern. We identified no signs of a recent bottleneck. The proximity to multiple glacial refugia explains the outcomes

Delineation of seed zones for European beech (Fagus sylvatica L.) in the Czech Republic based on isozyme gene markers

Seed zones for European beech (Fagus sylvatica L.) in the Czech Republic were proposed on the basis of isozyme polymorphism. Twenty beech populations distributed over the natural range of beech in the target area were analyzed using 12 isozyme loci. Analysis of genetic distances revealed the existence of geographical differentiation patterns. Allelic frequencies were estimated for a square network of 300 points, covering the territory of the Czech Republic, employing kriging as an optimum spatial interpolation method. Cluster analysis based on allelic profiles of the kriging points made it possible to divide the investigated area into eight seed zones. (© Inra/Elsevier, Paris.)Définition de régions de provenances pour le hêtre européen (Fagus sylvatica L.) en République Tchèque sur la base de marqueurs isoenzymatiques. La proposition de régions de provenances en République Tchèque pour le hêtre commun (Fagus sylvatica L.) a été basée sur l'étude de son polymorphisme isoenzymatique. Pour cela, vingt populations de hêtre, réparties sur l'aire d'extension naturelle dans le territoire examiné ont été analysées pour 12 loci isoenzymatiques. L'analyse des distances génétiques a montré l'existence d'une structuration géographique. Les fréquences alléliques ont été estimées par la méthode de krigeage, méthode d'interpolation spatiale, pour un réseau quadratique de 300 points recouvrant l'ensemble du territoire tchèque. L'analyse cladistique basée sur les profils alléliques en tout point du krigeage a permis de diviser la zone examinée en huit régions de provenances (© Inra/Elsevier, Paris.