Wälder beeinflussen mit ihrer Baumartenzusammensetzung den Wasserhaushalt und damit die Tiefensickerung. In dieser Studie wird der Effekt des Waldumbaus auf die Tiefensickerung von reinen Kiefernwäldern (Pinus sylvestris) über Mischwälder mit Kiefer, Buche (Fagus sylvatica) und Douglasie (Pseudotsuga menziesii) in reine Buchenwälder an drei grundwasserfernen und sandigen Standorten in Nordwestdeutschland untersucht. Basierend auf Messungen von meteorologischen Parametern, Bestandsniederschlag und Bodenfeuchte wird die Tiefensickerung mit dem Modell LWF-Brook90 zwischen Januar 2019 und Oktober 2020 berechnet. Im Vergleich zu reinen Kiefernwäldern zeigt sich keine Änderung der Tiefensickerung in Mischwäldern, während sie in reinen Buchenwäldern deutlich ansteigt. Jedoch zeigt sich, dass Durchforstungen die Tiefensickerung erhöhen. Die Ergebnisse dienen als Grundlage für eine ökonomische Bewertung der Tiefensickerung als Ökosystemdienstleistung.
Forests affect the water balance and thus deep seepage rates differently depending on species composition. Here, the effect of forest conversion on deep seepage rates is investigated in pure and mixed forests of pine (Pinus sylvestris), beech (Fagus sylvatica) and Douglas fir (Pseudotsuga menziesii) at three groundwater-distant and sandy forest sites in Northwest Germany. Based on continuous meteorological, stand precipitation and soil moisture measurements between January 2019 and October 2020, deep seepage rates are modelled with the hydrological model LWF-Brook90. Compared to pure pine forests, modelled deep seepage rates do not increase in mixed forests, but strongly increase in pure beech forests. The results further indicate that tree thinning increases deep seepage rates significantly. These modelled deep seepage rates serve as a basis for an economic evaluation of groundwater recharge as an ecosystem service to promote groundwater-emphasized forest conversion.
von Damián Leonardo Arévalo Martínez ; Amir Haroon ; Hermann Werner Bange ; Ercan Erkul ; Marion Jegen ; Nils Moosdorf ; Jens Schneider von Deimling ; Christian Berndt ; Michael Ernst Böttcher ; Jasper Hoffmann ; Volker Liebetrau ; Ulf Mallast ; Gudrun Massmann ; Aaron Micallef ; Holly A. Michael ; Hendrik Paasche ; Wolfgang Rabbel ; Isaac Santos ; Jan Scholten ; Katrin Schwalenberg ; Beata Szymczycha ; Ariel Tremayne Thomas ; Joonas J. Virtasalo ; Hannelore Waska ; Bradley A. Weymer
"Coastal observatories are key to improve the understanding of processes within the coastal area and their interactions with regional and global environmental changes. The land-sea transition zone is an essential area that allows research on unique scientific questions under anthropogenic and natural influences. Amid the Wadden Sea UNESCO world natural heritage site – the largest tidal flat region worldwide – the barrier island Spiekeroog is an excellent location for an observatory studying land-sea interactions. The integrated Spiekeroog Coastal Observatory (SCO) operated by the Institute for Chemistry and Biology of the Marine Environment (ICBM, University of Oldenburg) is dedicated to interdisciplinary marine and terrestrial ecosystem research. Its position within the tidal area and the multitude of research-field addressed establishes the SCO as a unique coastal observatory with the potential to identify patterns in long-term variability and simultaneously understanding short-term changes. The establishment of the Time-Series Station (TSS) Spiekeroog in a tidal channel west of Spiekeroog back in 2002 laid the foundation of the SCO. Since then, the observatory is expanding continuously and is now representing a valuable asset supporting education, industry, government, and environmental conservation efforts in the area. Summing up the infrastructure and technical components, the importance of the SCO is evident, and individual projects greatly benefit from the collaboration with the partners in and the elements of the SCO. Harmonizing the infrastructure and competences of contributing partners will be a next step to further consolidate the SCO. A challenge poses the maintenance of the SCO based on projects, which is focused on the addition of new facilities, not maintaining, refurbishing, or (if necessary) deconstructing existing infrastructure. Therefore, structural support and funding opportunities not linked to projects but aiming to sustain observational capacities are required." (Abstract)
Frontiers in Marine Science Lausanne : Frontiers Media, 2014 8(2022), Artikel-ID 754905, Seite 1-28 Online-Ressource
Besides other environmental tracers, the use of the 3H-3He method enables the estimation of modern groundwater ages. Widely used in fresh groundwater studies, the combination of tritium (3H) and its stable daughter product tritiogenic helium-3 (3Hetrit), however, has so far only been applied in a few studies to date groundwater in coastal aquifers. The coastal aquifer presented in this study is located at the very young eastern part of the North Sea barrier island Spiekeroog, the so-called ‘Ostplate’, that is characterized by a currently developing freshwater lens. Previously field and numerical modeling studies showed that the groundwater salinity distribution within this coastal aquifer is largely determined by seawater infiltration during storm tides. The main aim of this study was to characterize the groundwater age distribution in a highly dynamic coastal aquifer using the 3H-3He age dating method. In addition, a transient 2-D density-dependent flow and transport model that was calibrated to groundwater heads and salinity was utilized to assess whether measured 3H-3He ages can be reliably simulated despite the mixing of distinctly different and time-variable 3H endmembers, i.e., freshwater and seawater. The numerical calculation of the 3H-3He age distribution, thereby, was based on the simulation of the fictive tracer ‘stable tritium’ (sum of 3H and 3Hetrit) and 3H. Even though the freshwater lens is very young, both field observations and simulation results indicate notably lower ages within the freshwater lens as compared to the age of the lens itself. Simulation results show that frequent seawater infiltration, most importantly during winter storm tides, and discharging water from the freshwater lens lead to a disturbance of the vertical age stratification below the beach. A comparison with direct ages shows that the chosen 2-tracer approach improves system understanding, especially with regard to dispersion effects.
Advances in water resources Amsterdam [u.a.] : Elsevier Science, 1977 Volume 149 (2021), article 103850, circa 10 Seiten Online-Ressource
