EGU21-14428
https://doi.org/10.5194/egusphere-egu21-14428
EGU General Assembly 2021
© Author(s) 2021. This work is distributed under
the Creative Commons Attribution 4.0 License.

Water accessed differently by Larix decidua according to an alpine gradient

Natalie Ceperley1,2,3, Rokhaya Ba3, Harsh Beria3,4, Anthony Michelon3, Joshua Larsen4,5,6, Torsten Venneman3, and Bettina Schaefli1,2,3
Natalie Ceperley et al.
  • 1University of Bern, Geography Institute, Hydrology, Bern, Switzerland (natalie.ceperley@giub.unibe.ch)
  • 2Oeschger Centre for Climate Change Research (OCCR), University of Bern, Bern, Switzerland
  • 3Institute of Earth Surface Dynamics, Department of Geosciences, University of Lausanne, Lausanne, Switzerland
  • 4Department. of Environmental Systems Science, ETH Zurich, Zurich, Switzerland
  • 5School of Geography, Earth and Environmental Sciences, University of Birmingham, United Kingdom
  • 6The Birmingham Institute of Forest Research (BIFoR), University of Birmingham, United Kingdom

Vegetation is the primary connection between land and atmosphere, thus the main player mediating the consequences of a changing climate on land cover and hydrology. A protected alpine catchment, with a larch grove (Larix decidua) at the upper limit of the forested area, the Vallon de Nant (Vaud alps, 1200 – 3050 m. a.s.l.), was chosen as a study site in parallel with ongoing hydrological observation. We analyzed the stable isotopes of water, δ18O and δ2H, in the xylem extracted from samples of 10 trees in 2 transects just above and below 1500 m. a.s.l. over the course of the 2017 and 2018 growing seasons.  We compared isotopic ratios withconcurrent observations of isotopes in precipitation, stream, soil water, and groundwater.  Isotopic content of xylem water was found to be fairly consistent, independent of the date within the season, and closely resembled shallow soil water, suggesting that recent precipitation dominated the water source.   Our results support that vegetation could experience a drought due to low levels of rainfall before the streamflow is impacted. Furthermore, they affirm current discussions that water source is elevation dependent for trees in mountain ecosystems, with summer precipitation being favored by higher elevation trees, such as these. This preference has significant implications when we project current changes of quantities of rain falling as snow versus rain in the future. And more importantly, changes the view of forest from that of a water “user” to that of a store and player in complex feedback mechanisms.

How to cite: Ceperley, N., Ba, R., Beria, H., Michelon, A., Larsen, J., Venneman, T., and Schaefli, B.: Water accessed differently by Larix decidua according to an alpine gradient, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-14428, https://doi.org/10.5194/egusphere-egu21-14428, 2021.

Corresponding presentation materials formerly uploaded have been withdrawn.