Needles and bark of Picea abies (L.) H. Karst and Picea omorika (Pancˇiç) Purk. as bioindicators of environmental quality

The paper presents the results of the research on the accumulation of nutrients and heavy metals in needles and bark of Picea abies and Picea omorika. In this research, the age of the needles and the content of the examined components in the soil were taken into account. The research was conducted within the area of the forest at the University botanic garden in Košice (Slovakia). The little acidification of the soil that was found under the spruce crowns slightly changed with the depth (0.0–0.2 m, 0.2–0.4 m, 0.4–0.6 m). Under the stand of P. abies, a lower content of organic matter was demonstrated, than under the trees of P. omorika. The tested soil samples were low in nitrogen, phosphorus and calcium, and sufficiently rich in potassium and magnesium. The spruce needles were dominated by macroelements, and their concentrations varied depending on age and species. Both P. abies and P. omorika needles were acidic, with 1-year-old needles showing higher acidity. Low nitrogen content in the needles of the studied spruce was found, and the N:P ratio did not exceed 3.5. Statistically significant differences were found in the content of N, K, Ca, Zn, Mn, Fe, Ni, Cu and Cd in 1-year-old needles and pH, N, P, Ca, Zn, Mn, Fe, Ni, Cu and Cd in 2-yearold needles of spruces. The results also indicate that the bark of the studied spruce is acidic, with pH values of 4.70 (P. abies) and 4.15 (P. omorika). The P. abies bark accumulates higher amounts of Mg, Ca, Ni, Cu and Mn, and the P. omorika bark accumulates more N, P, K, Zn, Fe and Cd. The research indicates that both spruce species barks are suitable for comparative studies on bioindication of environment quality.