Abstract: The sulfur content in different parts of the twig the same year is different, i.e. leaf bark wood. Variation exists in different tree species in seasons and appears to be in positive retation with atmospheric SO2 concentration. The bark of hibernal twig of the deciduous leaves possesses significant capacity of sulfur absorption which is interrelated with the total opening of lenticelle and is also influenced by the surface structure of stems as well. This paper presents a regression equation and a calculation chart for monitoring SO2 pollution by sulfur content detected in the bark in winter at some regions in Shenyang. The results are in concert with those determinated by the physical-chemical methods.

Key words: Populus canadensis, Sulfur content in bark, Atmosphere SO2 concentration in winter