Über die SO₂-Resistenz von Flechten und die mit Ihr Interferierenden Faktoren

Abstract

The SO₂ resistance of 23 lichen species was determined by measuring the decrease of the pho-tosynthetic intensity after SO₂ gas-exposure. The most resistant species is Lecanora conizae-oides which penetrates deepest into the cities. The sequence of the species arranged according to increasing ‘poleophoby’ in the cities often differs considerably from that arranged according to increasing sensitivity to SO₂ found in the SO₂ gas-exposure experiments. The sensitivity to SO₂ is rather independent on the growth form. There are sensitive and insensitive species within the fruticose, foliaceous and crustaceous growth form groups. Factors affecting the SO₂ resistance are physical and chemical conditions which may cause reduction of the toxicity of SO₂ (for inst. a high buffer capacity of thallus and substrate and possibly the content of certain lichen substances), morphological and anatomical properties which may hinder the penetration of S0₂ into the thallus (as a thick cortex), and water availability, water content and water capacity of the lichen which influence the absorption of SO₂.

Diese Arbeit wurde im Rahmen eines Forschungsauftrages an Prof. Dr. O. L. Lange mit Unterstützung der Deutschen Forschungsgemeinschaft durchgeführt. Herrn Prof. Dr. S. Huneck, Halle, danken wir für Auskünfte zum Chemismus von Flechtenstoffen.