projection of independent variables after PCA. Stand characteristics are marked in black, while variables related to site conditions are in grey. (MAP): mean annual precipitation; (AHYC): absolute height-yield class; (DGS): duration of growing season; (MAAT): mean annual air temperature; (DOS): density of stocking.

source: Becvárová, P., Horváth, M., Sarapatka, B., & Zouhar, V. (2018). Dynamics of soil organic carbon (SOC) content in stands of Norway spruce (Picea abies) in central Europe. iForest-Biogeosciences and Forestry, 11(6), 734.