Figure 6.

The Principal Component Analysis (PCA) presents the relationships between selected photosynthetic parameters, pigment content and element content of the silver birch from various sites. Legend: green triangle—reference population from Tychy; black rhombus—birch population from post-coal mine spoil heap; blue circle—birch population from post-smelter spoil heap. Abbreviations: Ca—calcium concentration in leaves; Mg—magnesium concentration in leaves; Mn—manganese concentration in leaves; Zn—zinc concentration in leaves; TRW—mean tree-ring width throughout the life of the tree; A—photosynthetic rate; E—transpiration rate; Thi—leaf thickness; Anth—anthocyanin content; Chl—chlorophyll content; Flav—flavonol content; NPQ_T and φ_NPQ—non-photochemical quenching; LEF—linear electron flow; φ_II—quantum yield of photosystem II; PSI _AC—active centres of photosystem I.