The influence of Norway spruce and European beech on the vertical distribution of Cd, Cu, Pb and Zn in temperate forest soils

The objective of this study was to assess the influence of European beech (Fagus sylvatica L.) and Norway spruce (Picea abies (L.) H. Karst.) on the vertical distribution of Cd, Cu, Pb and Zn in forest soil. Soil samples were taken from six beech- and six spruce-dominated mature (80-100-year-old) forest stands. In total, 420 composite soil samples were collected from the organic horizons, and at depths of 0-2, 2-10, 10-20 and 20-30 cm in the mineral soil, of 84 plots in a hexagonal sampling design. A direct influence of forest type was confirmed for Zn, which showed increased soil accumulation under beech. In spruce stand soils, Zn is likely to have leached more due to lower pH levels. While a minor influence of tree species on the vertical distribution of Cd, Cu and Pb was also confirmed, particularly as regards accumulation in the F + H layer of spruce stands, the results suggest a more dominant effect of other site-specific conditions at the scale studied, such as topography and atmospheric deposition, despite homogenous forest stand conditions. Furthermore, the C:N ratio had a significant impact on both Cd and Cu content, regardless of forest type, highlighting the importance of specific site conditions for driving decomposition of organic matter, a primary factor affecting Cd and Cu mobility in soil.

Automated summary

The study aimed to investigate the impact of European beech and Norway spruce on the vertical distribution of Cd, Cu, Pb, and Zn in forest soil. Soil samples were collected from mature forest stands dominated by beech and spruce, and the results showed that beech had a direct influence on Zn accumulation in the soil. Other factors such as topography and atmospheric deposition were found to have a more dominant effect on the distribution of Cd, Cu, and Pb, despite homogeneous forest stand conditions. Additionally, the C:N ratio significantly affected the content of Cd and Cu, highlighting the importance of site-specific conditions in driving organic matter decomposition and influencing metal mobility in soil.