Nitrogen Leaching of Two Forest Ecosystems in a Karst Watershed

摘要: Karst watersheds are a major source of drinking water in the European Alps. These exhibit quick response times and low residence times, which might make karst aquifers more vulnerable to elevated nitrogen (N) deposition than non-karst watersheds. We summarize 13 years monitoring NO 3 − , NH 4 + total N two forest ecosystems, Norway spruce (Picea abies (L.) Karst.) on Cambisols/Stagnosols (IP I) mixed beech (Fagus sylvatica L.) Leptosols II). fluxes calculated by multiplying concentrations, measured biweekly intervals, with hydrological predicted from model. The throughfall amounts 26.8 21.1 kg/ha/year IP I II, respectively, is high compared depositions found other ecosystems. While shallow at II accumulated average 9.2 kg/ha/year between 1999 2006, budgets were equaled over study period but show inter-annual variation. Between average, 9 kg/ha/year DON 20 kg/ha/year DIN output seepage only 4.5 kg/ha/year 7.7 kg/ha/year II. Despite leaching, neither nor showed further signs saturation their organic layer C/N ratios, mineralization, or leaf content. budget all years was dominated few extreme events. Nitrate leaching rates both ecosystems correlated most above snow accumulation (but for this correlation statistically significant). Both melt annual precipitation important drivers leaching. comparable temporal patterns concentrations flux exhibited differences magnitudes: DON, inputs peak spring, an additional autumn; bulk occurred spring; during winter months low. related cover effects mineralization soil hydrology. From year 2004 onwards, disproportional plots. This possibly caused exceptionally dry 2003 small-scale bark beetle infestation (at I), addition effects. shows that Zobelboden still limited. pulses, particularly dictate not also long-term budgets. overall magnitude aquifer differs substantially types, close proximity karstified areas Northern Limestone Alps Austria.