SULFITE AND PH EFFECTS ON CO2 EVOLUTION BY FUNGI GROWING ON DECOMPOSING CONIFEROUS NEEDLES

The relative sensitivities of Mycena galopus (Pers.) Kummer, Phoma exi gua (Desm.), Cladosporium cladosporioides (Fres.) de Vries and Aureoba sidium pullulans (de Bary) Arnaud to low concentrations (12.5-100.0 mu M) Of sulphite (SO32-) when growing on decomposing needles of Picea s itchensis (Bongard) Carriere (Sitka spruce) and Pinus sylvestris L. (S cots pine) were assessed. Carbon dioxide evolution from the decomposin g needles was strongly inhibited by SO32- at pH 3.0-4.5. P. exigua was the most sensitive of the species tested in the mycelial state, and C . cladosporioides was the most sensitive species tested as spores. Myc elium was consistently less sensitive than spores. The inhibitory effe ct of SO32- on CO2 evolution was increased by increasing the SO32- con centration or decreasing the pH. The concentrations shown to exert tox icity were similar to those which have been measured in rainfall in th e UK, and the results provide evidence that SO32- can be toxic to litt er fungi at environmentally realistic concentrations.