title: Impacts of management and climate change on nitrate leaching in a forested karst area.
abstract: Forest management and climate change, directly or indirectly, affect drinking water resources, both in terms of quality and quantity. In this study in the Northern Limestone Alps in Austria we have chosen model calculations (LandscapeDNDC) in order to resolve the complex long-term interactions of management and climate change and their effect on nitrogen dynamics, and the consequences for nitrate leaching from forest soils into the karst groundwater. Our study highlights the dominant role of forest management in controlling nitrate leaching. Both clear-cut and shelterwood-cut disrupt the nitrogen cycle to an extent that causes peak concentrations and high fluxes into the seepage water. While this effect is well known, our modelling approach has revealed additional positive as well as negative impacts of the expected climatic changes on nitrate leaching. First, we show that peak nitrate concentrations during post-cutting periods were elevated under all climate scenarios. The maximal effects of climatic changes on nitrate concentration peaks were 20-24 mg L(-1) in 2090 with shelterwood or clear-cut management. Second, climate change significantly decreased the cumulative nitrate losses over full forest rotation periods (by 10-20%). The stronger the expected temperature increase and precipitation decrease (in summer), the lesser were the observed nitrate losses. However, mean annual seepage water nitrate concentrations and cumulative nitrate leaching were higher under continuous forest cover management than with shelterwood-cut and clear-cut systems. Watershed management can thus be adapted to climate change by either reducing peak concentrations or long-term loads of nitrate in the karst groundwater.
authors.affiliation: Environment Agency Austria, Department for Ecosystem Research and Data Information Management, Spittelauer Lände 5, 1090, Vienna, Austria. Electronic address: thomas.dirnboeck@umweltbundesamt.at.
authors.forename: Thomas
authors.initials: T
authors.lastname: Dirnböck
authors.affiliation: Environment Agency Austria, Department for Ecosystem Research and Data Information Management, Spittelauer Lände 5, 1090, Vienna, Austria.
authors.forename: Johannes
authors.initials: J
authors.lastname: Kobler
authors.affiliation: Karlsruhe Institute of Technology, Institute of Meteorology and Climate Research, Atmospheric Environmental Research (IMK-IFU), Kreuzeckbahnstraße 19, 82467, Garmisch-Partenkirchen, Germany.
authors.forename: David
authors.initials: D
authors.lastname: Kraus
authors.affiliation: Karlsruhe Institute of Technology, Institute of Meteorology and Climate Research, Atmospheric Environmental Research (IMK-IFU), Kreuzeckbahnstraße 19, 82467, Garmisch-Partenkirchen, Germany.
authors.forename: Rüdiger
authors.initials: R
authors.lastname: Grote
authors.affiliation: Karlsruhe Institute of Technology, Institute of Meteorology and Climate Research, Atmospheric Environmental Research (IMK-IFU), Kreuzeckbahnstraße 19, 82467, Garmisch-Partenkirchen, Germany.
authors.forename: Ralf
authors.initials: R
authors.lastname: Kiese
mesh_terms: D001317:Austria; D002980:Climate; D057231:Climate Change; D004784:Environmental Monitoring; D016468:Forestry / Q000379:methods; D065928:Forests; D060587:Groundwater / Q000737:chemistry*; D008962:Models, Theoretical; D009566:Nitrates / Q000032:analysis* / Q000737:chemistry; D009584:Nitrogen / Q000032:analysis / Q000737:chemistry; D012621:Seasons; D012987:Soil
chemical_list: D009566:Nitrates; D012987:Soil; D009584:Nitrogen
keywords: Ecological modelling; Forest clear-cut; Forest growth; Forest management; LTER Zöbelboden; LandscapeDNDC