Dose—response relationships for SO₂ fumigations in the lichens Evernia prunastri (L.) Ach. and Ramalina fraxinea (L.) Ach.

Abstract

SUMMARYSulphur dioxide fumigation of the lichens Evernia prunastri (L.) Ach and Ramalina fraxinea (L.) Ach, whose thallus water content was held at 100-120",, throughout each experiment, resulted in changes in net photosynthesis, dark respiration and chlorophyll content in relation to both concentration and duration of exposure. Net photosynthesis was the most sensitive response variable. Significant reduction in chlorophyll content was found when no recovery in net photosynthesis occurred after two weeks. A reduction in dark respiration was only found at high SO., concentrations. Evernia prunastri was affected by lower concentrations and shorter exposure times than Ramalina fraxinea and the data for both species showed dose-response relationships.

Monitoring Lichen as Indicators of Atmospheric Quality

“…With the increasing sulphur dioxide concentrations, a transformation of chlorophyll a into phaeophytin along with a reduction of chlorophyll content was observed (Hällgren and Huss 1975;Kong et al 1999). Chlorophyll reduction in fruticose lichen E. prunastri was observed only after severe damage to photosynthesis (Sanz et al 1992). The experimental results were in accordance with pigment losses reported under the field conditions (Gonzalez and Pignata 1994;Gonzalez et al 1998;Silberstein et al 1996a;Garty et al 1998).…”

Effects of coal dust on species composition of mosses and lichens in an arid environment

“…Many pollutants, including sulfur dioxide (Henriksson & Pearson, 1981;Pearson, 1985;Will-Wolf, 1980;Sanz et al, 1992), heavy metals, nitrogen dioxide, and hydrogen flourides ( Gough & Erdman, 1977;Nash & Sommerfield, 1981) inhibit lichen growth and survival. Coal-fired power plants can be a source of these substances and thereby indirectly cause damage to lichens (Belnap & Harper, 1990).…”

Severe photobiont injuries of lichens are strongly associated with air pollution

“…Physiological (Garty et al, 1997) and ultrastructural (Holopainen, 1983) changes in the lichens provide a means of detecting the effects of pollution at low levels before visible changes in lichen growth and on species distribution are apparent. The early responses of lichens to SO # are usually seen in the photobiont as reduced photosynthetic rate (Sanz et al, 1992) and ultrastructural damage to chloroplasts and mitochondria (Holopainen & Ka$ renlampi, 1984 ;Eversman & Sigal, 1987).…”