In subsoils, organic matter (SOM) concentrations and microbial densities are much lower than in topsoils and most likely highly heterogeneously distributed. We therefore hypothesize, that the spatial separation between consumers (microorganisms) and their substrates (SOM) is an important limiting factor for carbon turnover in subsoils. Further, we expect microbial activity to occur mainly in few hot spots, such as the rhizosphere or flow paths where fresh substrate inputs are rapidly mineralized. In a first step, the spatial distribution of enzyme and microbial activities in top- and subsoils will be determined in order to identify hot spots and relate this to apparent 14C age, SOM composition, microbial community composition and soil properties, as determined by the other projects within the research unit. In a further step it will be determined, if microbial activity and SOM turnover is limited by substrate availability in spatially distinct soil microsites. By relating this data to root distribution and preferential flow paths we will contribute to the understanding of stabilizing and destabilizing processes of subsoil organic matter. As it is unclear, at which spatial scale these differentiating processes are effective, the analysis of spatial variability will cover the dm to the mm scale. As spatial segregation between consumers and substrates will depend on the pore and aggregate architecture of the soil, the role of the physical integrity of these structures on SOM turnover will also be investigated in laboratory experiments.
This subproject aims at the development of spectral electrical impedance tomography (EIT) as a non-destructive tool for the imaging, characterization and monitoring of root structure and function in the subsoil at the field scale. The approach takes advantage of the capacitive properties of the soil-root interface associated with induced electrical polarization processes at the root membrane. These give rise to a characteristic electrical signature (impedance spectrum), which is measurable in an imaging framework using EIT. In the first project phase, the methodology is developed by means of controlled rhizotron experiments in the laboratory. The goal is to establish quantitative relationships between characteristics of the measured impedance spectra and parameters describing root system morphology, root growth and activity in dependence on root type, soil type and structure (with/without biopores), as well as ambient conditions. Parallel to this work, sophisticated EIT inversion algorithms, which take the natural characteristics of root system architecture into account when solving the inherent inverse problem, will be developed and tested in numerical experiments. Thus the project will provide an understanding of electrical impedance spectra in terms of root structure and function, as well as specifically adapted EIT inversion algorithms for the imaging and monitoring of root dynamics. The method will be applied at the field scale (central field trial in Klein-Altendorf), where non-destructive tools for the imaging and monitoring of subsoil root dynamics are strongly desired, but at present still lacking.
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Eine vorsorgende Anpassungsstrategie braucht Starkregenrisiko- u.a. Gefahrenkarten, die die Resilienz ggü. Klimawandelrisiken erhöhen helfen. Das Vorhaben soll Klimadienste entwickeln, die diese u.a. Daten und Informationen für einen vorsorgenden Umgang kommunaler und privater Entscheider besser nutzbar machen, indem Ansätze zur Verbesserung der 'Adaptation Literacy' konzipiert und beispielhaft in Peer Groups ausgetestet werden. Konkret sollen Klimadienste für diese Anwendungsfälle entwickelt werden, die verfügbare wissenschaftliche Datengrundlagen (wie Gefahren- und Risikokarten) so transformieren, dass Entscheider in der Lage sind, Adaptation Literacy aufzubauen und diese Daten und Informationen vorsorgend zielgenau zu nutzen. Zielgruppe sind Verbände und Vereinigungen beispielweise aus den Bereichen Planung, Architektur, Ingenieurwesen und Infrastrukturen. Folgende Instrumente sind angedacht: zielgruppengerechte Aggregation von Daten und Informationen, Training von Nutzern als 'Anpassungs-Botschafter' für gesellschaftlich relevante Bereiche, Erstellung von eLearning Angeboten. Das Vorhaben kann auf folgende Vorhaben aufbauen: Umsetzung von Klimaanpassungsdiensten im KliVo-Portal, Klimadapt Netzwerk, Stakeholderdialoge und Peer Learning.
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