The Influence of Air Pollutants on Needles and Stems of Scots Pine (Pinus Sylvestris L.) Trees

The influence of air pollution on the chemical composition of needles and stem anatomy (cambium, phloem, and xylem) of Scots pines (Pinus sylvestris L.) was examined in polluted and control forest sites near Warsaw, Poland. Foliar chemical composition was determined as an indicator of contamination of the trees examined anatomically. Anatomical analysis was carried out on samples including phloem, cambium, and current-year xylem collected at the breast height and from the tree top of the leader during one growing season. At the control site in current-year foliage, concentrations were N 1.53%, P 0.18%, K 0.5%, Ca 0.17%, Mg 910 ppm, Na 45 ppm, and S 0.145%, while at the polluted site concentrations were N 1.73%, P 0.18%, K 0.66%, Ca 0.35%, Mg 1509 ppm, Na 105 ppm and S 0.201%. Concentrations of heavy metals were significantly higher at the polluted site; only Mn was found in lower concentration. In trees from the polluted site, anatomical analysis revealed a decreased number of cambial cells at the beginning of growing season, phloem cells (at the tree top average number in a radial file was 21 and 14 in control and polluted sites, respectively), and formation of false rings with tracheids, similar to those in compression wood. Anatomical changes observed in trees from polluted sites are most likely caused by toxic effects of pollutants.