Annual Variations of Needle Surface Characteristics of Pinus Sylvestris Growing Near the Emission Source

In present study, pollutant effects on needle surface characteristics of Pinus sylvestris in the area affected by a nitrogen fertilizer plant have been investigated over 1994–1997 year period. Near the factory, sites with 15–25-year-old trees on a 0.5–22 km interval were chosen. Mean monthly concentrations of NO₂ and NH₃ varied across the transect in the range of 1.8–8.8 μg m-3 and 1.8–69.3 μg m-3, respectively. NH₃ concentrations exceeded the critical level (>23 μg m-3) only in the 0.5 km vicinity. Assesment of needle surface wettability by measuring contact angles (CA) of water droplets and surface quality by measuring stomatai area covered by structural wax (SW) revealed significant (p<0.05) needle age, site, and year of sampling related differences. Comparison of SW between sites showed reliably (p<0.05) higher surface wax erosion on one-year-old needles sampled in the area, where ammonia concentration exceeds critical level. Significant correlations between site SW on one-year-old needles and distance from the pollution source, NO₂ and NH₃ concentrations were detected (r = 0.539; r =-0.495; r =-0.426; p<0.001, respectively). Correlations between CA and factors mentioned were lower.