Sulphite and pH effects on CO2 evolution from decomposing angiospermous and coniferous tree leaf litters
1993
Dursun, S. | Ineson, P. | Frankland, J.C. | Boddy, L.
The relative sensitivities of decomposing leaf litters to low concentrations (12.5-100.0 micromolars) of sulphite were assessed. The experimental litter comprised four broadleaf species (Ulmus glabra Hudson, Betula sp., Quercus sp., Fagus sylvatica L.) and two conifer species [Picea sitchensis (Bongard) Carr. and Pinus sylvestris L.]. Carbon dioxide evolution from the coniferous litter was strongly inhibited by SO2-3 at pH 3.0-6.0, P. sylvestris being the most sensitive of the litters tested. The broadleaf litters were consistently less sensitive than the coniferous litters. The inhibitory effect of SO2-3 on CO2 release from litter was increased by increasing the SO2-3 concentration or decreasing the pH; coniferous litter respiration was inhibited strongly by SO2-3 at pH 3.0 and 4.0 over 7 days. Spores of Cladosporium cladosporioides (Fres.) de Vries were more sensitive than mycelium growing on decomposing P. sylvestris litter, and both were markedly inhibited by 100.0 micromolars SO2-3 at pH 3.0 for 14 days. The concentrations shown to exert toxicity were the same as those which have been measured in U.K. rainfall and the results provide confirmatory evidence that SO2-3 exhibits a toxic effect on litter fungi at environmentally-realistic concentrations.
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