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LTER Zöbelboden - Coupling long-term monitoring and ecosystem modelling to study nitrogen cycling in a small karst catchment in Austria

Thomas Dirnböck1, Johannes Kobler1, Michael Mirtl1
1 Ecosystem research and Environmental Information Management, Environment Agency Austria

O 1.5 in Long term trends in the functioning of ecosystems

14.07.2014, 15:15-15:35, H18

Karst watersheds are a major source of drinking water in the European Alps. These watersheds exhibit quick response times and low residence times, which might make karst aquifers more vulnerable to nitrate pollution. At LTER Zöbelboden in the Northern Limestone Alps in Austria, nitrogen cycling was monitored in a small (90 ha) forested catchment during 20 years and effects of elevated nitrogen deposition, forest disturbances (windthrow, bark beetle) and management were studied. Analyses of long-term data showed that relatively high nitrate losses are to be found in the seepage water (on average 20 kg Ninorg.ha-1.yr-1) although no other signs of nitrogen saturation are apparent. Runoff peaks during snow melt drives these fluxes. Additionally, forest disturbances have a strong impact. The ecosystem model Landscape DNDC was used to model nitrogen cycling of contrasting forest stands at the plot scale and a catchment model was applied to upscale nitrate losses to the karst springs. The models were applied with various scenarios of climate change and different forest management options. Results exemplify the dominant impact of forest management on nitrate losses. Based on our results optimal strategies for forest as well as karst water management were developed which lower possible pollution risk.



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last modified 2014-01-28