The aim of this study was to estimate the effect of topographic factors and soil properties on the productivity of Norway spruce stands in the Sudety Mountains, Poland. pH, organic C and N contents, hydrolytic and exchangeable acidity, cation contents (Ca2+, Mg2+, K+, and Na+), and soil texture were determined. We present soil properties from five parent material types and include separate analyses for the organic and humus-mineral soil horizons. Edaphic factors, together with topography, were significantly related to the Norway spruce site index. Soil properties from the humus-mineral horizon or the organic horizon (with features of topographic position included in the models) accounted for 67% and 56% of the site index variability, respectively. Elevation, the Al3+/effective cation exchange capacity ratio, and C and K+ contents were significant individual predictors of site index. A regression analysis indicated that elevation explains 49% of the site index variability.
Keywords: mountains forest sites; soil properties; site index.