Radial growth of woody plants is a vital process that controls carbon sequestration and significantly contributes to climate change mitigation. In regions with seasonality of climate, wood formation occurs episodically during periods with favorable conditions for cell division and expansion. Temperature and moisture interact during the growing season to determine (i) whether growth can be sustained, and if so, (ii) what speed radial growth can achieve at a given moment. However, we lack information about how growing season duration, occurrence of daily growth events, and growth rate during these events interact in determining the overall annual growth rate and how their importance changes across spatial gradients.
The Ph.D. candidate will take part in a project funded by the Czech Science Foundation (GACR) that aims to address the variation in the importance of growth rate, growth occurrence, and growing season duration for annual tree growth across geographical gradients and over time. The candidate will establish new plots of intensive dendrometer monitoring in dry, moderate, and cold coniferous forests across the Czech Republic to extend the already existing network of monitoring sites run by our team. Dendrometers are used to record fine stem size (radius or circumference) variation driven by radial growth and changing amount and state of internal stem water content. Next, the candidate will analyze the recorded data from new as well as old dendrometer plots to statistically separate the contribution of growth phenology, growth rate, and growth occurrence to total annual wood production. To do this, the candidate will employ established statistical approaches including linear and non-linear regressions and/or wavelet analysis. The variable importance of growing season duration, growth occurrence, and growth rate as predictors of total annual growth will be assessed in relation to site and climatic conditions of each stand.
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). Currently, we maintain dendrometer plots for monitoring of intra-annual growth dynamics in the Czech Republic (5x), Southern Norway (2x), Pyrenees (2x), and Northern Sweden (1x).
You hold an M.Sc. degree (or equivalent) in Geography, Ecology, Biology, Forestry, Plant (Eco)physiology, or a related discipline. We are looking for a highly motivated candidate with a strong scientific interest in plastic responses of trees to climate change, fieldwork, and data analysis. Previous education and/or practical experience in these areas is a strong advantage. The ability to use R or other programming language is welcome. The ideal candidate will proactively contribute to the research project with their expertise and by developing their research ideas. The candidate should be able to join fieldwork related to the installation, maintenance, and reading of dendrometer plots. 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., Scharnweber, T., Smiljanic, M., Wilmking, M., 2022. Limitation by vapour pressure deficit shapes different intra‐annual growth patterns of diffuse‐ and ring‐porous temperate broadleaves. New Phytol. 233, 2429–2441. https://doi.org/10.1111/nph.17952
Tumajer, J., Braun, S., Burger, A., Scharnweber, T., Smiljanic, M., Walthert, L., Zweifel, R., Wilmking, M., 2023. Dendrometers challenge the ‘moon wood concept’ by elucidating the absence of lunar cycles in tree stem radius oscillation. Sci. Rep. 13, 19904. https://doi.org/10.1038/s41598-023-47013-y