Experimental sites are placed in the vicinity of Načetín research station in Ore Mts. (Czech Republic). The area has experienced dramatic fall in S deposition (from 50 kg S ha-1 yr-1 in early 1990s to 11 kg S ha-1 yr-1 in late 2000s) and no change in bulk N deposition since 1990s (average of 10 kg N ha-1 yr-1). Over the same time period ecosystem N leaching decreased dramatically (from 20 kg N ha-1 yr-1 to 1 kg N ha-1 yr-1). At the research station 2 forest types are present – 70 years old managed Norway spruce plantation and 120 years old European beech forest. New experimental sites were established in mature conifer (Norway spruce) and mature broad leave (European beech) forests on the same bedrock and close to each other. At each site replicated plots (4 replicates) of 4 different treatments were established. The treatments consist of a) control treatment, b) acid treatment (as H2SO4, with equivalent deposition of 50 kg S ha-1 yr-1), nitrogen treatment (as NH4NO3, with equivalent deposition of 50 kg N ha-1 yr-1), and d) combined acid + nitrogen treatment (with equivalent deposition of 50 kg S and 50 kg N ha-1 yr-1). All treatments are applied evenly (monthly) using watering cans. All together, 32 plots at 2 sites were established.