Master Thesis

How silica drives ecosystem service of peatlands

Gloria Reithmaier (05/2015-08/2016)

Support: Jörg Schaller, Britta Planer-Friedrich, Sebastian Arnhold, Thomas Koellner

Peatlands perform important ecosystem services, such as carbon storage, nutrient retention, and water quality regulation, which are influenced by peat decomposition. Since decomposition of organic material was recently shown to be accelerated by silicon (Si), the aim of this study was to examine how Si influences the ecosystem services of peatlands. Therefore, a Si fertilization experiment was conducted at a German fen site. Under enhanced Si availability dissolved organic carbon, carbon dioxide and methane concentrations increased significantly, confirming that Si negatively affects carbon storage. Furthermore, dissolved nitrogen, phosphorus, iron, manganese, cobalt, zinc, and arsenic concentrations were significantly higher under Si enriched conditions. The enhanced element mobilization may result from Si competing for binding sites and stronger reducing conditions, which are due to accelerated decomposition. The stronger reducing conditions also amplified the reduction of arsenate to arsenite. Based on the biogeochemical results, the nitrogen and phosphorus balance was modeled using SWAT, revealing strongly enhanced exports under elevated Si availability. Hence, increased Si concentrations negatively affect nutrient retention and water quality regulation. A wide range of dissolved Si was proven in 18 nearby fens, suggesting a strong influence of Si on peatland ecosystem services.