Distribution of genetic diversity in Fagus sylvatica at the north-eastern edge of the natural rangeKempf M., Konnert M. (2016). Distribution of genetic diversity in Fagus sylvatica at the north-eastern edge of the natural range. Silva Fennica vol. 50 no. 4 article id 1663. 17 p. http://dx.doi.org/10.14214/sf.1663. Highlights• European beech at the north-eastern edge of its natural range in Poland have a high level of genetic variation, similar to the populations from Central Europe.• The differences between the beech provenances from the two centres in Poland, which were previously identified on the basis of pollen analyses and phenotypic traits, have now been genetically confirmed. AbstractAn understanding of the genetic variation of the beech, especially at the edge of its natural distribution, is essential because of the change in natural distribution of the species resulting from changing climatic conditions. The main aim of the study was to determine the level of genetic diversity of European beech at the north-eastern edge of its natural range. The other aim was to check the genetic variation of beech from the two centres, the north and the south of Poland, which were identified in previous findings based on pollen analyses and phenotypic traits. The research material was the progeny of twelve beech provenances. The genetic structure of the populations was determined by ten highly variable microsatellite DNA loci. The results confirmed the high genetic diversity of beech at the north-eastern edge of its natural distribution, which infers the probability of their good adaptation to the changing climate and an extension of the range. Genetic analyses confirmed the existence of two genetic centres for beech in Poland. The populations from south-eastern Poland had a slightly higher diversity than the populations from the north-western area, which may indicate that the colonisation of Poland occurred by two routes. The results are important for creating the borders of the provenance regions and for limiting the transfer of seeds and seedlings. The choice of forest reproductive material, based on the knowledge of genetic diversity, is very important for the stability of future forests.

Polycyclic aromatic hydrocarbons (PAHs) are among the most hazardous organic pollutants due to their toxic, carcinogenic, mutagenic properties, wide distribution, recalcitrance and stability in the environment. The study objective is to determine the impact of the species composition of tree stands on PAH accumulation in urban forest soils of Krakow. The study compared the impact of deciduous and coniferous species on similar soils on PAH biodegradation. Basic physicochemical properties, activity of enzymes involved in the nutrient cycle and PAH content were measured in soil samples. Our study shows lower accumulation of PAHs in soils with deciduous tree stands, which are characterized by higher pH and higher biochemical activity expressed by enzymatic activity. There is statistically significant difference in the enzymatic activity in the soils of deciduous tree stands, which results in differences in PAH accumulation. Among the studied deciduous species, soils with Norway maple and locust were characterized by highest enzymatic activity. At the same time, soils under these species were characterized by the lowest PAH accumulation. Among the coniferous species, highest PAH accumulation was observed under pine and spruce, where low enzymatic activity was observed at the same time.

Populations of smaller effective sizes or subjected to strong environmental filtering have a higher risk of stochastic changes in their genetic properties. This study tested the hypothesis that reducing the density of parent trees combined with environmental filtering during the stage of regeneration establishment affects gene flow between the parent and offspring populations of Abies alba Mill. The genetic variation and spatial genetic structure of parent trees and seedlings were compared in the Western Carpathians (southern Poland) in 27 stands with varying adult tree and regeneration densities. The analysis comprised 1592 individuals and was based on five nuclear microsatellite markers. The proportion of stands with significant spatial genetic structure in the adult tree and seedling cohorts increased as the density of adult trees decreased. The genetic differentiation between adult trees and seedlings expressed by the fixation index F ST was between 0.005 and 0.021 and increased as the density of adult trees decreased but was not correlated with the seedling abundance. At the within-stand level, the analysis revealed shifts in the average number of alleles per locus (between − 15% and + 28%), the observed heterozygosity (between − 25% and + 20%) and expected heterozygosity (between − 8% and + 11%) between the populations of adult trees and seedlings. It was concluded that in mixed stands with densities of A. alba trees about 50 adult individuals per ha, there may be some risk of reduced effective population size and disturbed vertical gene flow, but significant shifts in the level of genetic variation are less likely.

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