Wood ash and nitrogen influence on ground vegetation cover and chemical composition

An experiment was set up in a 38-year-old Scots pine stand (forest type Pinetum vacciniosum) on a sandy soil (Haplic Arenosol). Raw wood ash (WA) and nitrogen (N) fertilizers were applied. There were 6 treatments: (1) 1.25 t WA ha⁻¹; (2) 2.5 t WA ha⁻¹; (3) 5.0 t WA ha⁻¹; (4) 180 kg N ha⁻¹; (5) 2.5 WA t ha⁻¹ together with 180 kg N ha⁻¹; and (6) control (without ash or N). The effects on ground vegetation cover, biomass and chemistry of Pleurozium schreberi (Brid.) Mitt. were studied.The ground vegetation cover measurements were performed from the initial phase of the experiment and continued annually in all treatments. The ground vegetation biomass and the concentrations of the main plant nutrients (N, P, K, Ca and Mg) and some heavy metals (Cr, Cd, Pb, Ni, Cu and Zn) were determined in the 5.0 t WA ha⁻¹ and 180 kg N ha⁻¹ plots 2 years after the application.The study results showed a significant reduction of the moss cover after the application of wood ash, and the higher ash dose gave a higher decrease. N and wood ash applied together with N also decreased the cover of the moss. Small changes in the mean cover of the vascular plants occurred after the N application. The biomass of the moss remained unaffected. Significant increases of the P, Ca and Mg concentrations in P. schreberi were found after the application of 5.0 t WA ha⁻¹, and also higher N concentrations were obtained after N application. No wood ash influence on the heavy metal (Cd, Pb, Cr, Ni, Cu and Zn) concentrations in P. schreberi was found.