Eichen im Aargau – eine besondere Verantwortung für das Fricktal | Oak in the canton of Argovia – a special responsibility for the Fricktal
A targeted nurturing of oak in the canton of Argovia goes against the natural development of forest stands where the dominant, naturally occurring species is beech. Because of this, afforestation with oak is both work intensive and costly and is therefore concentrated on sites where silvicultural, economical and ecological aspects have been taken into account. With the help of a simple model showing areas where, above all, oak is nurtured, comprehensively mapped forest stands were classed according to competitiveness and correlated to thermal levels, that represent an important site factor for oak. One important aspect surrounding the issue is the preservation of genetic resources and an adequate supply of appropriate seed from chosen autochthonal, indigenous oak stands. In addition, the endangered population of middle spotted woodpecker, which is tied to widespread sites of aged oak-rich deciduous stands, should be fostered. Taking ecological priorities into account a possible area to nurture oak has bee...
Autochthon oder allochthon? Ein molekulargenetischer Ansatz am Beispiel der Eichen (Quercus spp.) in der Schweiz
Autochthonous forests are considered to be valuable genetic resources, and their conservation is incorporated into many national forest programmes. The methods applied so far often do not allow to distinguish between autochthonous and allochthonous stands. Therefore, alternative methods are needed. In this study, we analyse spatial patterns of variation of chloroplast DNA to estimate the extent of the human influence on oak stands in Switzerland.
Phylogeographic structure of white oaks throughout the European continent.
Patterns of chloroplast DNA (cpDNA) variation were studied in eight white oak species by sampling 345 populations throughout Europe. The detection of polymorphisms by restriction analysis of PCR-amplified cpDNA fragments allowed the identification of 23 haplotypes that were phylogenetically ordered. A systematic hybridization and introgression between the eight species studied is evident. The levels of subdivision for unordered (GST) and ordered (NST) alleles are very high and close (0.83 and 0.85). A new statistical approach to the quantitative study of phylogeography is presented, which relies on the coefficients of differentiation GST and NST and the Mantel's test. Based on pairwise comparisons between populations, the significance of the difference between both coefficients is evaluated at a global and a local scale. The mapped distribution of the haplotypes indicates the probable routes of postglacial recolonization followed by oak populations that had persisted in southern refugia, especially in the Iberian peninsula, Italy and the Balkans. Most cpDNA polymorphisms appear to be anterior to the beginning of the last recolonization. A subset of the preexisting haplotypes have merely expanded north, while others were left behind in the south.