Project summary

Treeline ecotones at high latitudes (polar treeline) and high elevations (alpine treeline) are generally temperature-limited environments. However, evidence is increasing that temperature control on tree growth at treelines has recently decreased due to climate change, while water availability can be a seasonally important growth-limiting factor. More studies are needed i) at the intra-annual (wood cell) level and ii) considering multiple growth-limiting factors to better understand these complex climate-growth responses at treelines.

The PhD project will help to bridge this gap by using 1) quantitative wood anatomy and 2) process-based models of wood formation to systematically assess climate-driven intra-annual tree growth dynamics for representative polar and alpine treeline sites in Eurasia and North America. For 1), the candidate will prepare microscopic thin sections of wood, measure xylem anatomical traits (cell lumen area, cell wall thickness, cell number) using semi-automated software, and establish statistical relationships between xylem anatomical traits and climate. For 2), process-based models of tree growth will be calibrated and used to simulate wood formation at daily resolution. All analyses will be based on a set of existing and newly collected samples (tree cores) from polar and alpine treeline sites in Eurasia and North America.

We are seeking a candidate with strong interest in dendroecology, wood anatomy, field and laboratory work, and modeling/programming. Previous education and/or practical experience in these areas is a strong advantage. The working language is English; therefore, a very good command of English is required. The ideal candidate should have a multi-disciplinary attitude, be willing to learn new approaches, and have the ability to work independently as well as in a team. Highly motivated students from various disciplines (Geography, Ecology, Forestry, and related fields) are encouraged to apply.

The PhD project is part of and co-financed by the GAČR (Czech Science Foundation) project no. 22-26519S: “Using forward modelling to unravel the complex climatic control on intra-annual tree growth at cold distribution margins”, 2022-2024, PI: Jelena Lange.

Relevant publications of the research group

Lange, J., Carrer, M., Pisaric, M. F. J., Porter, T. J., Seo, J.-W., Trouillier, M., et al. (2020). Moisture-driven shift in the climate sensitivity of white spruce xylem anatomical traits is coupled to large-scale oscillation patterns across northern treeline in northwest North America. Global Change Biology 26, 1842–1856. DOI: 10.1111/gcb.14947

Tumajer, J., Kašpar, J., Kuželová, H., Shishov, V. V., Tychkov, I. I., Popkova, M. I. et al. (2021): Forward modeling reveals multidecadal trends in cambial kinetics and phenology at treeline. Frontiers in Plant Science 12, S. 613643. DOI: 10.3389/fpls.2021.613643.

Tumajer, J., Buras, A., Camarero, J. J., Carrer, M., Shetti, R., Wilmking, M. et al. (2021): Growing faster, longer or both? Modelling plastic response of Juniperus communis growth phenology to climate change. Global Ecology and Biogeography 30 (11), S. 2229–2244. DOI: 10.1111/geb.13377.

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