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PRELUDIUM (NCN) project for PhD student Liliana Siekacz

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PRELUDIUM (NCN) project for PhD student  Liliana Siekacz

Title: Blue rings chronology and microanatomical parameters of tracheids – a new line of proxy evidence of environmental constraints in north American Bristlecone Pine.

The supervisors of Ms.  Siekacz are: Dr. Marcin Koprowski  and Dr. Charlotte Pearson (University of Arizona, Laboratory of Tree-Ring Research).

The classical dendrochronological approach uses the whole width of individual dated tree-rings which is controlled by climatic conditions in the year of growth. Proposed project plans to take dendroclimatic reconstructions to the higher level of time resolution, extracting an intra-annual climatic signal from the dimensional parameters of individual cells in each growth year. The main goal of the project is to create a chronology of unlignified and underlignified rings, which show up as 'blue-rings' when certain stains are applied, covering the last 2000 years. This will provide high resolution insight into the environmental changes recorded by Bristlecone pine (Pinus longaeva), by understanding which environmental parameters trigger the formation of particular structures. Lignification is one of the last stages of annual tree-ring development, the phenomenon of 'blue-rings' has only been known about for a few years ago and it is believed that they are the result of a sudden drop in temperature at the end of the growing season, however, studies show that this phenomenon might be strongly diverse and depend on species and local conditions. The selected species is particularly suitable for planned analysis. Bristlecone pine is a unique tree, thanks to its longevity and strong climate sensitivity it has been used in many fields of research, including on climate reconstruction and in creating the radiocarbon calibration curve. Literature also indicates the unique sensitivity of this species to climate fluctuations resulting from climatically effective volcanic eruptions - growth minima and frost rings correlate with large volcanic eruptions. Preliminary studies carried out so far by the PhD student indicate that blue rings are even more sensitive to temperature changes than frost rings because their formation does not require negative thermal conditions that damage the macroscopic structure of wood as it is required in the case of frost rings. The results of the project will allow a better understanding of the climate-growth relationships, and the created chronology will bring new information on climatically effective volcanic eruptions that occurred in the distant past and are not historically documented.

The project will be implemented in cooperation with the Laboratory of Tree Ring Research, University of Arizona in Tucson (USA). This laboratory provides access to its research equipment, as well as its wood collection which is the largest research wood archive in the world. The project will use collection of Bristlecone Pine material created by Dr Matthew Salzer, the leading expert in the species. The project also involves cooperation with Dr Charlotte Pearson dendroarcheologist specializing in information about environmental impact on past civilizations encoded in tree rings, dendrochemistry and radiocarbon dating, and is PhD student supervisor.

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