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Keywords:

  • Acid deposition;
  • Betula;
  • birch pollen;
  • seed germination

summary

Laboratory experiments showed that mountain birch pollen u as sensitive to the acidity of the incubation solution : the percentage of pollen germination was significantly reduced (compared to control, pH 5.6) at pH 4.0 and the length of the longest germ tube was reduced by nearly 50% at pH 4.6. On the other hand, the pollen germination percentage was not significantly affected by treating the male catkins of mountain birch with acid spray down to pH 3.0. Furthermore, a field experiment with simulated acid rain did not show any significant treatment effects either on the number or size of female catkins or on the seed germination capability of mountain birch. There are several mechanisms which may compensate and buffer the effects of acidity on the reproduction of trees.