Acidification and recovery of soil at a heavily impacted forest catchment (Lysina, Czech Republic)—SAFE modeling and field results

Soil and soil solution chemistry were simulated using the dynamic multi-layer soil chemistry model SAFE for the Lysina catchment, located in the western part of the Czech Republic. Modeled soil solution chemistry and properties were compared to a 10-year-long time series of monthly measurements of soil solution data at 5, 15, 20 and 80cm depths. Historically high deposition of S and N compounds caused a significant decrease in soil base saturation and caused severe changes in the soil solution chemistry. Since year 1990 deposition of S and N compounds decreased substantially due to improved control on S emissions. SAFE predicted an increase in base saturation at Lysina in the Oi+Oe and Oa layers, from 36% and 18% in 1994 to 50% and 22% in 2004, respectively. On the other hand, base saturation of the deeper soil horizons B and C, which represent the main mass of the soil at the Lysina catchment, has decreased even further (in B horizon from 4% in 1994 to 3% in 2004 and from 4% to 2% in horizon C). The measured values of base saturation from year 2004 fit the modeled results of base saturation development at the Lysina catchment. If atmospheric deposition remains at the 2006 level, the predicted base saturation in the B and C horizons for the year 2100 will increase by approximately 2% to reach only 4.6% and 3.8%, respectively. The increasing molar ratio Bc/Al [(Ca+Mg+K)/Al] in soil solution of Oi+Oe, Oa and E horizons during the first half of the 21st century represents recovery in the top 20cm of the soil profile, only. This change may have a positive effect on the health status of shallow rooting spruce trees. The Bc/Al ratio in soil solutions in the main mass of the soil (horizons B and C), however, will remain below the critical value (<1) in the first half of 21st century. At the Lysina catchment, the values of the Bc/Al ratio are predicted to increase over the critical value (<1) in solutions of the B and C horizons in the years 2050 and 2060, respectively.