Impact of Sulphur and Nitrogen Dioxide Concentration on Radial Increment Dynamics of Scots Pine (Pinus Sylvestris L.) Growing in Cities

Abstract

Trees growing in city forest parks and parks are exposed to the permanent higher air pollution level than trees growing in the relatively clean environment. Study of tree response towards changes in acidifying pollutants' (SO₂ and NO₂) concentration dynamics is relevant, as forest parks and parks fulfil a lot of beneficial functions in cities. Scots pine (Pinus sylvestris L.) sample trees, growing in parks and forest parks in Vilnius and Kaunas cities, were chosen as the objects of this research. Wood samples were collected from 330 sample pines in 15 sample plots in Kaunas city and from 480 sample pines in 20 sample plots in Vilnius city. Dendroscales of radial increment of pines growing in cities were transformed into sequences of the radial increment ratio for eliminating an impact of tree age without removing a negative impact of anthropogenic pollution. Reduction in NO₂ and SO₂ concentration in the atmosphere could determine an increase in pine radial increment in 1990-2006: significant relation was estimated between radial increment and NO₂ concentration in Vilnius and Kaunas cities (mean correlation coefficient r was equal to- -0.61 and -0.62, respectively, p<0.05), also SO₂ - in Vilnius city (r=-0.65, p<0.05). In the period of 1990-2006 climatic factors determined a larger percentage of complex impact (74-88 %) on pine radial growth in comparison with the concentration of acidifying pollutants (12-26 %).