EFFECTS OF AIR POLLUTION ON MORPHOLOGICAL AND ANATOMICAL CHARACTERISTICS OF PINUS ELDARICA WOOD
Air pollution, including automobile exhaust pollution, can affect anatomical and morphological characteristics of wood. In order to evaluate this subject, the Pinus eldarica trees of Chitgar Park in Tehran, which extends from a crowded highway in the south (polluted site) to the semi polluted midsection and to Alborz Mountain in the north (unpolluted site) were sampled with an increment borer and cores were collected. After cross dating, the tree rings of the last five years were separated from the rest of the core. Anatomical characteristics of the cross sections, including the transition between early wood and latewood, the tangential thickness of the last-formed latewood tracheids, the frequency of rays and resin ducts and the morphological characteristics of tracheids in rings formed in the same year were studied. The results indicated that the ring widths of P. eldarica in the three zones are not significantly different. Rays and false rings were more frequent in the polluted and semi polluted sites than in the reference area, and wall thickness was significantly different in some years. Other morphological properties did not differ significantly except for tracheid diameted. In conclusion air pollution does not alter P. eldarica ring width significantly but changes some anatomical and morphological properties of its wood. Therefore trees growing on polluted sites are not suitable for Dendrochronological studies.