Sulphite and pH effects on CO₂ evolution by fungi growing on decomposing coniferous needles

Abstract

The relative sensitivities of Mycena galopus (Pers.) Kummer, Phoma exigua (Desm.), Cladosporitim dadosporioides (Fres.) de Vries .and Aureobasidium puUulans (de Bary) Arnaud to low concentrations (12-5-lOO'O/JM) of sulphite (SO/") when growing on decomposing needles of Picea sitchensis (Bongard) Carriere (Sitka spruce) and Pinus sylvestris L. (Scots pine) were assessed. Carbon dioxide evolution from the decomposing needles was strongly inhibited by SO^"' at pH 3'0-4-5. P. exigua was the most sensitive of the species tested in the mycelial state, and C. dadosporioides was the most sensitive species tested as spores. Mycelium was consistently less sensitive than spores. The inhibitory effect of SO^^" on COj e\'olution was increased by increasing the SO^^" concentration or decreasing the pH. The concentrations shown to exert toxicity were similar to those which have been measured in rainfall in the UK, and the results provide evidence that SO.,'^" can be toxic to litter fungi at environmentally realistic concentrations.