Challenges in studying water fluxes within the soil-plant-atmosphere continuum: A tracer-based perspective on pathways to progress

Natalie Orlowski; Michael Rinderer; Maren Dubbert; Natalie Ceperley; Markus Hrachowitz; Arthur Gessler; Youri Rothfuss; Matthias Sprenger; Ingo Heidbüchel; Angelika Kübert; Matthias Beyer; Giulia Zuecco; Colin McCarter

doi:10.1016/j.scitotenv.2023.163510

Challenges in studying water fluxes within the soil-plant-atmosphere continuum: A tracer-based perspective on pathways to progress

Sci Total Environ. 2023 Jul 10:881:163510. doi: 10.1016/j.scitotenv.2023.163510. Epub 2023 Apr 12.

Authors

Affiliations

¹ Hydrology, Faculty of Environment and Natural Resources, University of Freiburg, Freiburg im Breisgau, Germany. Electronic address: natalie.orlowski@hydrology.uni-freiburg.de.
² Hydrology, Faculty of Environment and Natural Resources, University of Freiburg, Freiburg im Breisgau, Germany; Geo7 AG, Bern, Switzerland.
³ Isotope Biogeochemistry and Gasfluxes, ZALF, Müncheberg, Germany.
⁴ Institute of Geography, University Bern, Switzerland.
⁵ Department of Water Management, Faculty of Civil Engineering and Geosciences, Delft University of Technology, Stevinweg 1, 2628CN Delft, Netherlands.
⁶ Forest Dynamics, Swiss Federal Research Institute WSL, Birmensdorf, Switzerland; Institute of Terrestrial Ecosystems, ETH Zurich, Zurich, Switzerland.
⁷ Institute of Bio- and Geosciences, Agrosphere (IBG-3), Forschungszentrum Jülich GmbH, Jülich, Germany; Terra Teaching and Research Centre, University of Liège, Gembloux, Belgium.
⁸ Earth and Environmental Sciences at the Lawrence Berkeley National Laboratory, Berkeley, USA.
⁹ Hydrological Modelling, University of Bayreuth, Bayreuth, Germany; Hydrogeology, Helmholtz Centre for Environmental Research - UFZ, Leipzig, Germany.
¹⁰ Institute for Atmospheric and Earth System Research (INAR), University of Helsinki, Helsinki, Finland.
¹¹ Institute for Geoecology, Technische Universität Braunschweig, Braunschweig, Germany.
¹² Department of Land, Environment, Agriculture and Forestry, University of Padova, Legnaro, Italy; Department of Chemical Sciences, University of Padova, Padova, Italy.
¹³ Department of Geography, Department of Biology and Chemistry, Nipissing University, North Bay, Ontario, Canada.

PMID: 37059146
DOI: 10.1016/j.scitotenv.2023.163510

Abstract

Tracing and quantifying water fluxes in the hydrological cycle is crucial for understanding the current state of ecohydrological systems and their vulnerability to environmental change. Especially the interface between ecosystems and the atmosphere that is strongly mediated by plants is important to meaningfully describe ecohydrological system functioning. Many of the dynamic interactions generated by water fluxes between soil, plant and the atmosphere are not well understood, which is partly due to a lack of interdisciplinary research. This opinion paper reflects the outcome of a discussion among hydrologists, plant ecophysiologists and soil scientists on open questions and new opportunities for collaborative research on the topic "water fluxes in the soil-plant-atmosphere continuum" especially focusing on environmental and artificial tracers. We emphasize the need for a multi-scale experimental approach, where a hypothesis is tested at multiple spatial scales and under diverse environmental conditions to better describe the small-scale processes (i.e., causes) that lead to large-scale patterns of ecosystem functioning (i.e., consequences). Novel in-situ, high-frequency measurement techniques offer the opportunity to sample data at a high spatial and temporal resolution needed to understand the underlying processes. We advocate for a combination of long-term natural abundance measurements and event-based approaches. Multiple environmental and artificial tracers, such as stable isotopes, and a suite of experimental and analytical approaches should be combined to complement information gained by different methods. Virtual experiments using process-based models should be used to inform sampling campaigns and field experiments, e.g., to improve experimental designs and to simulate experimental outcomes. On the other hand, experimental data are a pre-requisite to improve our currently incomplete models. Interdisciplinary collaboration will help to overcome research gaps that overlap across different earth system science fields and help to generate a more holistic view of water fluxes between soil, plant and atmosphere in diverse ecosystems.

Keywords: Ecosystem research; Hydrology; Interdisciplinary perspectives; Isotope tracers; Plant ecophysiology; Soil science; Water fluxes.