ABSTRACT
Arnolds (1989a,b; 1991; 1997) suggested that the decline in the appearance of ectomycorrhizal fruit bodies and the increase in saprotrophic and pathogenic fungal fruit bodies in The Netherlands is associated with a combination of acidifying pollutants, and in particular, nitrogen deposition (Termorshuizen and Schaffers, 1987; 1991; Kårén and Nylund, 1997). Although there is little experimental evidence showing the effects of acidifying pollutants on saprotrophic mushroom-forming fungi, Kuyper (1989) gives evidence that nitrogen addition and the effects of liming, (to offset the effects of acidifying pollutants) stimulate saprotrophic fungi and leaf litter decomposition where nitrogen levels in the leaf litter are low, but suppress saprotrophic activity where leaf litter nitrogen content is high. He also shows that the effect of liming on mycoflora is very similar to that of nitrogen fertilization. Although they did not observe significant changes in the ectomycorrhizal species composition, Antibus and Linkins (1992) showed that the effect of liming reduced the acid phosphatase activity of the mycorrhizal
community in the litter layer of the forest floor. They did not explore how the relative availabilities of nitrogen and phosphorus in soil played a part in this, but it could be surmised that there is a synergistic activity of liming on increasing both N and P availability, thus reducing phosphatase activity by negative feedback mechanism.
