Dendroprovenancing instream wood at the watershed scale applying fingerprinting techniques
- Institute of Earth Surface Dynamics, University of Lausanne, Lausanne, Switzerland *(Javier.delhoyo@unil.ch)
Within the field of dendrochronology, different sub-disciplines arise using the information stored in the wood for a variety of purposes. In this study, we use dendroprovenance to develop a methodology that allows us to infer the source area of instream large wood (LW) at the river basin scale applying fingerprinting techniques.
LW is mainly supplied to fluvial ecosystems by riparian vegetation and nearby areas, and the presence of wood in a river determines its geomorphology and ecology; but also, it is associated with an increase in danger and risk to infrastructures and population. For this reason, research on the origin of LW is essential to better understand LW processes and to facilitate decision-making in the management of the forest and the river.
The tracers we have used so far are the stable isotopes coming from the water molecule: hydrogen (D/H) and oxygen (18O/16O). These isotopes show spatial variations depending on evaporation-precipitation processes and resulting isotopic fractionation. Subsequently, the water absorbed by a tree growing in a particular place stores this isotopic signal, and when that tree (or a piece of it) falls and becomes part of the river ecosystem, we can use this isotopic signal to infer the origin of the wood.
Our study site is a 50 km reach of the Rhone River between Lake Geneva and Genissiat dam (3000 km2 of catchment) in France, where all arriving wood is stored upstream from the dam. The goal is to differentiate the wood coming from the two main tributaries, the Arve and Valserine rivers (located in different mountain systems) since they are the main wood suppliers at Genissiat.
Preliminary results show clear differences in the isotopic composition when comparing samples from one tributary and the other, with the most notable differences in the most recent tree rings.
Lastly, we plan to analyze other tracers such as minor and trace elements that are linked to the geology and combine them with the isotopic ratios in a multivariate analysis to determine the origin of the wood in a more accurate manner. Consequently, we will have developed a new dendroprovenance method that can be extrapolated to other fields, taking a step forward in the application of our knowledge about tree rings.
How to cite: del Hoyo Gibaja, J., Vennemann, T., Vauridel, M., and Ruiz-Villanueva, V.: Dendroprovenancing instream wood at the watershed scale applying fingerprinting techniques, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-7719, https://doi.org/10.5194/egusphere-egu22-7719, 2022.
