A long-term study of the effects of simulated acid rain on birch leaf phenolics

Effects of prolonged simulated acid rain (sulphuric and/or nitric acids; two acidities, pH 4 and pH 3) on the phenolic biochemistry of mountain birch (Betula pubescens ssp. czerepanovii) foliage was studied in the far north of Finnish Lapland. Even after 10 years of treatments, there was only one significant difference among the treatments: in mid-July, content of total phenolics was higher in birch leaves from acid rain treatments than in controls. On the other hand, differences among subares located close to each other were clearly larger than differences among the treatments. There were no significant differences among the treatments in contents of proanthocyanidins, total content of gallotannins or in contents of individual low molecular mass phenolics. In conclusion, phenolics of birch leaves do not seem to be sensitive to simulated acid rain.