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In the area of the western Balkans, xerothermal broad-leaf forests hold a very special position, the main species being pubescent oak (Quercus pubescens Willd.). The study comprises 36 populations of pubescent oak from Croatia, Bosnia and Herzegovina, Montenegro, Kosovo, Albania and Macedonia. Genetic variability and population diversity was analysed on chloroplast DNA in order to determine to which haplotype an individual or studied population belongs, as well as how they are related. For the detection of one haplotype analysed four sequences (AS, TF, DT and CD) on the chloroplasts DNA. The results of the analysis suggest that there are six different haplotypes of pubescent oak (2, 4, 5, 17, 31, 33) in the studied populations. Two more sub-haplotypes were found in haplotype 5 (a and b), but only in populations occurring in Croatia and Bosnia and Herzegovina. The results suggest the great variability of pubescent oak in the researched area, which is generally characteristic of other species from the area of the Balkan Peninsula. The results obtained by means of cpDNA analysis can help in the formation of seed zones. However, due to the strong selection pressure of unplanned logging, and the possible introduction of herbal material of unknown origin, it is necessary to find a sufficient number of autochthonous entities (i.e., populations of the researched species) as well as new suitable markers for their characterization. The results of this paper constitute a scientifically recognised, partial examination of the origin of the starting forest reproductive material from the broader geographic area, thus serving future projects on its regeneration.
Taxonomy of the genus Quercus L. is very complicated and often controversial because of its great variability and intense gene flow among the related species. The purpose of this research was to determine morphological and molecular variation, relationships and taxonomic status of the Croatian populations of Quercus pubescens Willd. using morphological analysis of the leaves and RAPD-PCR technique. The results of the morphological and molecular analyses were very similar, both showing differentiation of the southern (Mediterranean) from the northern (Continental) pubescent oak populations. These two groups were clearly separated and the estimated gene flow among the populations that belong to different groups (Nm=1.38) is significantly less than among the populations that belong to the same group (Nm=3.70). The obtained results were compared to the available studies. This study confirms a high variability of the Q. pubescens populations, but differences were not so big to confirm the opinion of existence of several species in this area. The conclusion is that the southern Croatian populations could be pure Q. pubescens populations, while the peculiarities of the northern Croatian populations originate probably from the Q. petraea introgression.
Quercus robur and Q. petraea are important forest-forming species in Europe. Q. robur is believed to require more fertile soils, to be more tolerant to low temperatures and more sensitive to oak decline than Q. petraea. Thus chronologies of the two species from nearby localities were hypothesised to differ more strongly between species than between localities. Wood cores were collected on 23 research plots in 2 national parks and 12 forest districts. In each locality two plots (one with Q. robur and one with Q. petraea) were established in forest stands of similar age at similar site conditions wherever possible. Similarity between chronologies was assessed by the test of parallel agreement (Gleichlaufigkeit), Pearson correlation coefficients, and principal components. The plots were grouped by the Ward clustering method and according to 1st and 2nd principal components. The first 2 methods segregated chronologies nearly ideally into pairs of species from the same forest district, indicating that the chronologies differ between forest districts but not between species. Chronologies clustered in 2 large groups: northern and southern (on the basis of correlation) or northeastern and southwestern (on the basis of parallel agreement). Principal components also distinguished northeastern and southwestern chronologies, but less clearly. The results suggest that differences in climatic and soil requirements between the 2 oak species are generally too small in comparison with the differences caused by climatic factors.
The number of world oak species is currently estimated at 450. The oak is predominant mainly in the temperate and northern subtropical climatic zones. Poland boasts three species: the common oak (Quercus robur), sessile oak (Quercus sessilis), downy-leaved oak (Quercus pubenscens). The article treats about their natural qualities, commercial properties and touches upon their significance in the mythology, history and culture.
The abaxial epidermis of pubescent oaks, Quercus brachyphylla Kotschy, Quercus dalmatica Radić and Quercus pubescens Willd., was studied with the Scanning Electron Microscope. Micro-morphological features (surface of trichomes, stomata, ordinary epidermal cells and wax) do not permit to distinguish the three oaks species. Nevertheless, the difference among the taxa exist in leaf phenology and time of appearance and rate of degradation of epicuticular wax crystalloids. Alteration of wax crystalloids into amorphous wax is interpreted in favour of natural phenomenon of the wax ageing and degradation.
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