Project summary

The intra-annual patterns of wood formation dynamics vary with space and over time due to changing climatic conditions. While unimodal growth with short growing seasons and peak growth rates around the summer solstice prevails in cold environments, growth bimodality (or multimodality) with long growing seasons dominates in seasonally dry regions. Nevertheless, the overall intra-annual growth pattern at a given site might shift as the climate becomes drier and warmer. Understanding the response of growth phenology (timing of growth) and kinetics (rate of growth) across large spatial gradients is essential to better predict the response of European forests to ongoing climate change.

The PhD candidate will take part in a project funded by the Programme ‘Johannes Amos Comenius’ that aims to better understand the response of forest ecosystems to the increasing frequency of hydrometeorological extremes including droughts, heat waves, and early spring frosts. The candidate will use dendrochronological methods to produce new tree-ring width chronologies from dry and cold sites across the Czech Republic and Europe to characterize annual variation of growth dynamics. To increase the spatial coverage of available chronologies, the candidate will also acquire suitable tree-ring data from public databases including the global ITRDB database and the new national TreeDataClim database (www.treedataclim.cz/en/home-english/). Next, the process-based models of wood formation, namely the Vaganov-Shaskin model and the VS-Lite model, will be applied to individual sites with available dendrochronological data to simulate intra-annual dynamics of radial growth. The candidate will assess how growth phenology and bimodality shift across the geographical gradients based on key model outputs including phenological dates (start of growing season, end of growing season), growth rates during the days with growth, and their overall distribution over the course of the year (growth bimodality X unimodality). Moreover, the same dataset will be used to quantify changes in growth phenology and growth patterns over time due to ongoing climate change.

About us

We are a young, growing, and highly international research team (https://web.natur.cuni.cz/physgeo/dendro/). Our research is focused on forest ecology and climatic effects on tree growth in temperate, boreal, and Mediterranean forests. We use various tree-ring proxies (tree-ring width, wood density/blue intensity, wood anatomy, isotopes) and other data sources (forestry databases, satellite imagery, dendrometers). Our dendrolab features state-of-the-art infrastructure (scanners, microtomes, microscopes, software).

Your profile

You hold an M.Sc. degree (or equivalent) in Geography, Ecology, Biology, Forestry, Biostatistics, or a related discipline. We are looking for a highly motivated candidate with a strong scientific interest in tree responses to climate change, fieldwork, and data analysis. Previous practical experience with methods of processing dendrochronological data – including field sampling, laboratory processing, and statistical evaluation – is a significant advantage. The ability to use R or Matlab (Octave) or similar statistical software is welcome. The ideal candidate will proactively contribute to the research project with their expertise and by developing their research ideas. The candidate is expected to join fieldwork related to sampling of dendrochronological material and contribute to its laboratory processing. A very good command of English is required (the working language of our diverse group is English).

Selected papers from our group linked to the topic of the PhD project

Tumajer, J., Altman, J., Lehejček, J., 2023. Linkage between growth phenology and climate-growth responses along landscape gradients in boreal forests. Sci. Total Environ. 905, 167153. https://doi.org/10.1016/j.scitotenv.2023.167153

Valeriano, C., Gutiérrez, E., Colangelo, M., Gazol, A., Sánchez-Salguero, R., Tumajer, J., Shishov, V., Bonet, J.A., Martínez de Aragón, J., Ibáñez, R., Valerio, M., Camarero, J.J., 2023. Seasonal precipitation and continentality drive bimodal growth in Mediterranean forests. Dendrochronologia 78, 126057. https://doi.org/10.1016/j.dendro.2023.126057

Tumajer, J., Buras, A., Camarero, J.J., Carrer, M., Shetti, R., Wilmking, M., Altman, J., Sangüesa‐Barreda, G., Lehejček, J., 2021. Growing faster, longer or both? Modelling plastic response of Juniperus communis growth phenology to climate change. Glob. Ecol. Biogeogr. 30, 2229–2244. https://doi.org/10.1111/geb.13377

Tumajer, J., Kašpar, J., Kuželová, H., Shishov, V. V., Tychkov, I.I., Popkova, M.I., Vaganov, E.A., Treml, V., 2021. Forward Modeling Reveals Multidecadal Trends in Cambial Kinetics and Phenology at Treeline. Front. Plant Sci. 12, 613646. https://doi.org/10.3389/fpls.2021.613643

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