Přehled

Background

Boreal forests cover about thirty percent of the world’s forest area, thus understanding their growth and response to environmental changes is crucial for assessing global patterns of carbon fluxes and energy cycles. However, patterns of recent climate change and weather extremes are highly complex and variable across space and over time, and it remains unclear how and where these conditions stress or promote tree growth. For example, there is increasing evidence that water availability and snow are more important for the inter- and intra-annual growth dynamics of boreal forest trees than previously thought, with potential consequences for forest vitality and range shifts.

Research field and aim

The main objective of this PhD project is to better understand how different climatic and other environmental factors influence the growth of boreal forests. To this end, dendrochronological methods, high-frequency growth monitoring and ecological field observations will be used, with a potential focus on the so far understudied early growing season (spring) and non-growing season (fall, winter).

Research tasks and methods

The student will establish chronologies of tree-ring widths and wood anatomical traits based on field sampling of dominant conifer species across the (Fennoscandian) boreal forest and extensive laboratory work. In addition, the student will use a new network of dendrometers and microclimatic soil and air loggers (to be installed in 2024) to estimate intra-annual growth dynamics and key phenological dates of radial growth (growth onset, ending, phases of growth/no-growth). Time series of tree-ring widths, wood anatomical traits, and dendrometer records will be statistically related to climate and weather data at different temporal scales (hours to decades) to disentangle the main climatic drivers and stressors of boreal forest growth in space and time. An analysis of the N and C content of soil and tissue (needles) is planned at the study sites in order to better understand the relationships between climate, tree growth and nutrient availability.

Requirements

We are seeking a highly motivated candidate with a M.Sc. degree (or equivalent) in Geography, Ecology, Biology, Forestry, or a related discipline. You should have a strong interest in dendrochronology, forest ecology, wood anatomy, field and laboratory work, and statistical analyses/programming. Previous experience in these areas is a strong advantage. Very good oral and written communication skills in English are required. The ideal candidate will contribute proactively to the research project by developing own research ideas and expertise and will have an independent, team-oriented working style.

Additional information

The fully funded PhD project (including salary, fieldwork expenses, equipment, and consumables) is part of the new interdepartmental research excellence program “Georisks” (JAK, 2024-2028). The successful candidate will join the structured, international, and interdisciplinary four-year PhD program of the Department of Physical Geography and Geoecology.

Selected publications of the research group related to the 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 Phytologist 233, 2429–2441. https://doi.org/10.1111/nph.17952

Pampuch, T., Anadon-Rosell, A., Trouillier, M., Lange, J., Wilmking, M. (2021): Direct and indirect effects of environmental limitations on white spruce xylem anatomy at treeline. Frontiers in Plant Science 12: 748055. https://doi.org/10.3389/fpls.2021.748055

Gurskaya, M.A., Lange, J., Kukarskih, V.V., Buras, A., Wilmking, M. (2021): Stationarity of climate-growth response is only marginally influenced by the soil moisture regime in Western Siberia. Dendrochronologia 69: 125873. https://doi.org/10.1016/j.dendro.2021.125873

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. https://doi.org/10.1111/gcb.14947

Lange, J., Buras, A., Cruz-García, R., Gurskaya, M., Jalkanen, R., Kukarskih, V., Seo, J.-W., Wilmking, M. (2018): Climate regimes override micro-site effects on the summer temperature signal of Scots pine at its northern distribution limits. Frontiers in Plant Science 9: 1597. https://doi.org/10.3389/fpls.2018.01597


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