Modelling ecohydrological feedbacks in forest and grassland plots under a prolonged drought anomaly in Central Europe 2018–2020. Issue 8 (18th August 2021)

• Record Type: Journal Article
• Authors: Kleine, Lukas; Tetzlaff, Doerthe; Smith, Aaron; Dubbert, Maren; Soulsby, Chris
• Is Part Of: Hydrological processes. Volume 35:Issue 8(2021)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2021-08-18
• Subjects: drought -- ecohydrology -- soil–plant‐atmosphere -- water ages -- water stable isotopes; Hydrology -- Periodicals; Hydrology -- Research -- Periodicals; Hydrologic models -- Periodicals; Hydrological forecasting -- Periodicals; 631.432
• DOI: 10.1002/hyp.14325
• Languages: English
• ISSNs: 0885-6087

Abstract

Abstract: Recent studies have highlighted the importance of understanding ecohydrological drought feedbacks to secure water resources under a changing climate and increasing anthropogenic impacts. In this study, we monitored and modelled feedbacks in the soil–plant‐atmosphere continuum to the European drought summer 2018 and the following 2 years. The physically based, isotope‐aided model EcH2 O‐iso was applied to generic vegetation plots (forest and grassland) in the lowland, groundwater‐dominated research catchment Demnitzer Millcreek (NE Germany; 66 km 2 ). We included, inter alia, soil water isotope data in the model calibration and quantified changing "blue" (groundwater recharge) and "green" (evapotranspiration) water fluxes and ages under each land use as the drought progressed. Novel plant xylem isotope data were excluded from calibration but were compared with simulated root uptake signatures in model validation. Results indicated inter‐site differences in the dynamics of soil water storage and fluxes with contrasting water age both during the drought and the subsequent 2 years. Forest vegetation consistently showed a greater moisture stress, more rapid recovery and higher variability in root water uptake depths from a generally younger soil water storage. In contrast, the grassland site, which had more water‐retentive soils, showed higher and older soil water storage and groundwater recharge fluxes. The damped storage and flux dynamics under grassland led to a slower return to younger water ages at depth. Such evidence‐based and quantitative differences in ecohydrological feedbacks to drought stress in contrasting soil‐vegetation units provide important insights into Critical Zone water cycling. This can help inform future progress in the monitoring, modelling and development of climate mitigation strategies in drought‐sensitive lowlands. Abstract : In this study, we included stable water isotopes of bulk soil water (model calibration) and plant xylem (model validation) to model ecohydrological feedbacks in the soil‐plant‐atmosphere continuum to the European drought 2018 and the following two years. The physically based model was setup at two plot sites in spatial proximity and differing landuse of forest and grassland in the Demnitzer Millcreek catchment in NE Germany. This revealed differences in drought effects and persistence on ecohydrological fluxes and water ages. Whereas the forest site had more variable water uptake strategies and younger bulk soil water ages, the grassland showed less dynamic water ages and root water uptake strategies. Such insights can help to inform the landuse based mitigation of droughts and there multi‐year effects in evapotranspiration and groundwater dominated lowlands.