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Huaitong Xu

Genetic structure, regeneration and fragmentation impact in eastern white cedar (Thuja occidentalis L.) populations in northern Quebec

It is anticipated that average temperature will rise about 3 to 5°C consequent to the increase in the concentration of greenhouse gases in the atmosphere (IPCC 2007), we can envisage a range expansion for the tree species, which will be particularly marked for populations located at the limit of their distribution range. A progressive fall in success of sexual reproduction resulted in a reduction in the capacity of these species to be maintained and to colonize new sites. Among the natural processes, disturbances (e.g. fire) play a role on species distribution at their upper latitudinal limit by altering the population density and limiting the reproduction capacity. The increasingly important fragmentation of tree populations towards their range limit could have an impact on their diversity and genetic structure.


The long-term objective is to improve our understanding of the relative influence of climate and disturbances on the dynamics and genetic structure of eastern white cedar populations in the boreal mixedwood. My study will have three objectives. The first will be to study the impact of climate on genetic and genotypic diversity in eastern white cedar. In Quebec boreal forest, the natural distribution of eastern white cedar populations along latitudinal gradient provides us an opportunity to investigate the climate impact on genetic and genotypic diversity in eastern white cedar. The second objective will be to address impact of forest dynamics (succession) on genetic and genotypic diversity in eastern white cedar. How important sexual and asexual regenerations of eastern white cedar along a post-fire succession will be addressed. The third objective will be to characterize the impact of fragmentation on genetic structure of eastern white cedar.

Yves Bergeron, Francine Tremblay, Huaitong Xu. Importance of landscape features and fire refuges on genetic diversity of Thuya occidentalis L., in boreal fire dominated landscapes. 2018. Cons. Gen. 19(5):1231-1241 DOI : 10.1007/s10592-018-1091-6  

Martin-Philippe Girardin, Huaitong Xu, Christopher Carcaillet, Johann Housset, Francine Tremblay, Yves Bergeron. In situ Comparison of Tree-Ring Responses to Climate and Population Genetics: The Need to Control for Local Climate and Site Variables. 2016. Frontiers in ecology and the environment 4:123 DOI : 10.3389/fevo.2016.00123  

Huaitong Xu. Génétique des populations de cèdre blanc de l’est (Thuja occidentalis l.) dans la forêt boréale du nord-ouest québécois. 2013. Thèse de doctorat en sciences de l'Environnement, Université du Québec en Abitibi-Témiscamingue. 123 p.  

Yves Bergeron, Francine Tremblay, Véronique Paul, Huaitong Xu, Cungen Chen. Genetic consequences of fragmentation in “arbor vitae,” eastern white cedar (Thuja occidentalis L.), toward the northern limit of its distribution range. 2012. Ecology and Evolution 2(10):2506-2520 DOI : 10.1002/ece3.371  

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Soutenance thèse: (2013-10-02)