Predicting the regional risk of elevated nitrate concentrations below forests in Bavaria by empirical modelling at different spatial scales

Abstract

Nitrogen saturation is currently one of the most important environmental issues in forests of Central Europe. In this study, a nested model design at different spatial scales is presented to predict the risk of elevated nitrate concentrations. The model was developed from a state‐wide inventory at about 400 stands and a complementary regional survey of 64 stands in the forests around Munich. High deposition of ammonium and low precipitation were significantly associated with high nitrate concentrations. Especially site properties and forest type influenced the risk of nitrate leaching significantly. At the regional scale the forest coverage and the stand age contribute considerably to explain the variance of the nitrate concentrations. The results suggest that forestry policy and practice could contribute to mitigate nitrogen saturation and nitrate leaching by conversion of spruce stands into mixed stands with a high percentage of deciduous trees.

Keywords:

• Nitrogen saturation
• Nitrate inventory
• Regionalization
• Logistic regression model
• Nested model design

Acknowledgements

We are indebted to all the laboratory and soil sampling staff who worked on this project. We thank Thomas Gauger for deposition data as well as Klaus Moritz, Christoph Schulz and Wendelin Weis for making available the monitoring data. Further we express our gratitude to the Bayerische Staatsministerium für Landwirtschaft und Forsten for funding the study.

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