In cities around the world, urban green spaces provide a range of benefits and ecosystem services. However, recent years have shown how prolonged warm and dry periods can affect urban water resources and lead to water stress in vegetation in urban green spaces, even in temperate regions. Consequently, quantitative knowledge about ecohydrological partitioning in different types of urban green space is crucial for balancing sustainable water needs in cities during future challenges of increasing urbanization and climate warming. Using isotopic tracers in precipitation and soil water, along with conventional hydrometric measurements in a plot-scale study in Berlin, Germany, we investigated water partitioning under different generic types of urban vegetation (grassland, shrub and trees). This allowed for the assessment of urban vegetation effects on evapotranspiration, subsurface flow paths and storage during a prolonged drought period with episodic rainfall. Despite higher soil evaporation losses under urban grassland, higher interception and transpiration likely contributed to slower turnover of soil water and older groundwater recharge under urban trees. Shrub vegetation seemed to be most resilient to prolonged drought periods, with lower evapotranspiration losses. Our results contribute to a better understanding of ecohydrological partitioning under mixed urban vegetation communities and an evidence base for better adaptive management of urban water and irrigation strategies to sustainably meet the water demands of urban green spaces in the future.
We thank the German Research Foundation (DFG) for funding this project as part of the Research Training Group “Urban Water Interfaces (UWI)” (GRK 2032/2) and the Einstein Foundation for the support as part of the project “Modelling surface and groundwater with isotopes in urban catchments (MOSAIC)”. We are especially thankful to our colleagues of the TU Berlin Ecology Department for providing access to their property and assistance for site selection, in particular Birgit Seitz, and to the Department of Climatology, especially Dieter Scherer and Fred Meier, for providing the UCO climate data. Further, we thank our colleagues Esther Brakkee, Larissa Lachmann, Nina-Sophie Weiß, Christian Marx, Lukas Kleine, Wiebke Lehmann, Hauke Dämpfling, David Dubbert, Anna Wieland, Jonas Freymüller, Sylvia Jordan and Mikael Gillefalk for assistance in the sampling and installation of equipment and David Dubbert for help with the isotope analysis. Finally, we thank the Berlin Senate Department for the Environment, Transport and Climate Protection for providing groundwater data and well access.
This research has been funded by the Deutsche Forschungsgemeinschaft (grant no. GRK 2032/2).
The publication of this article was funded by the
Open Access Fund of the Leibniz Association.