Student information

Msc thesis subject: What do trees tell us about drought?

Trees play an important role in the water cycle at local, regional and global scales. Information on tree water status gives valuable information on hydrological variables (e.g. transpiration, root water uptake, root zone soil moisture) and ecosystem functioning. Unfortunately, many tree-related variables are difficult to measure, as they are invasive (sap flow sensors), destructive (taking samples) and/or expensive (dendrometers).

Recent studies have investigated the use of accelerometers as a low-cost sensing technique to estimate tree properties and responses. Tree sway can be used to determine a tree’s natural frequency, which is dependent on mass and elasticity. Variation in natural frequency can for example be used to estimate the above ground biomass and intercepted rainfall by individual trees.

Objectives

  • In this study you will explore the relation between tree natural frequency and (1) diurnal variations in tree water status, (2) tree water stress and (3) leaf growth and senescence. Available datasets including tree sway timeseries (>6 months) of over 50 trees in various climatic regions.
  • This project will done in collaboration with the University of Cambridge (UK) and the University of Wisconsin-Madison (USA).

Literature

  • van Emmerik, T., et al. "Measuring tree properties and responses using low-cost accelerometers." Sensors 17.5 (2017): 1098.
  • Jackson, T., et al. "An architectural understanding of natural sway frequencies in trees." Journal of the Royal Society Interface 16.155 (2019): 20190116.
  • van Emmerik, T., et al. "Ideas and perspectives: Tree–atmosphere interaction responds to water-related stem variations." Biogeosciences 15.21 (2018): 6439-6449.

Requirements

  • data analysis,
  • frequency analysis,
  • vegetation-hydrology interaction

Theme(s): Sensing & measuring; Modelling & visualisation