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Projekt Druckansicht

Führt eine gesteigerte Siliziumverfügbarkeit zu eine Erhöhung der Mineralisierung von organischem Material in Niedermooren?

Fachliche Zuordnung Hydrogeologie, Hydrologie, Limnologie, Siedlungswasserwirtschaft, Wasserchemie, Integrierte Wasserressourcen-Bewirtschaftung
Ökologie und Biodiversität der Pflanzen und Ökosysteme
Förderung Förderung von 2017 bis 2021
Projektkennung Deutsche Forschungsgemeinschaft (DFG) - Projektnummer 327633020
 
Erstellungsjahr 2021

Zusammenfassung der Projektergebnisse

Major controls on decomposition in peatlands are the water table, the availability of nutrients and electron acceptors and the quality of the litter. In fen peatlands, graminoids often are the dominant vegetation type. Graminoids, especially Cyperaceae, can accumulate large quantities of Si. This element can be intensely recycled between plant and peat and it has been shown that Si influences the C biogeochemistry and turnover in soils. A higher availability of Si could for example mobilize P and stimulate decomposition processes by provision of P, or may have further effects on decomposition through altering litter quality. The conditions under which Si has effects on P mobilization and greenhouse gas production, are yet not well understood. This project thus addressed the role of Si in the C cycle and the effects of a changed Si availability in peatlands. We hypothesized that (i) a higher Si availability will enhance the mineralization of organic matter via direct Si effects and indirect Si effects by increasing P availability, (ii) the higher mineralization rate of organic matter to both CO2 and CH4 due to direct and indirect Si effects will be achieved rather by bacteria than by fungi and fungal biomass will be lowered by Si addition, (iii) increased Si availability will increase P and N availability and uptake into plant biomass and thus lead to more labile litter, in turn accelerating carbon and nutrient turnover, (iv) both the quantity of DOC and of dissolved N increases due to direct and indirect effects of Si on organic matter mineralization, and (v) the direct Si effect on peat mineralization is more important compared to the indirect effect of Si via enhancing P availability. We conducted incubation experiments with Si additions and using untreated and Si-fertilized plant litter. Moreover, a mesocosm experiment with and without Si-amendment was conducted to replace a field experiment that could not be performed to extensive drought at the intended field site. On the basis of the conducted experiments we could not give a final statement on hypothesis (v), and also for hypothesis (ii) we could not provide a final answer, as we could not disentangle the activities of fungi and bacteria due to huge variation in mineralization rates with no clear differences between treatments. Nevertheless, higher Si availability stimulated CH4 production in most of our experiments, while for CO2 no effect could be verified. Moreover, Si fertilization lead to more labile plant litter, accelerating decomposition, as verified in incubations and qualitative analyses of the respective litter types. Finally, under certain experimental conditions, the quantity of DOC was increased, however, this could not be confirmed for dissolved nitrogen. In summary, our project revealed that Si is an important driver for the C-turnover in peatlands und certain conditions.

Projektbezogene Publikationen (Auswahl)

 
 

Zusatzinformationen

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