On the relationships between nematodes, mycorrhizal fungi and plants: functional composition of species and plant performance

We analysed data from descriptive and experimental studies on the possible relationships between plants, nematodes and mycorrhizal fungi in (successional) plant communities in The Netherlands. A key role for pathogenic nematodes in cyclic succession in grazed grassland confirmed similar results in foredune succession. Plants with clonal growth forms appear to be particularly susceptible to pathogenic fungi. A large role for ectomycorrhiza at the species level (functional composition) was observed in determining the effects of acid rain and increased atmospheric CO2 on nutrient transfer to trees. Field studies showed a correlation between species richness of ectomycorrhizal fungi and hyphal-feeding nematodes in one case, but not in another. Population growth of hyphal-feeding nematodes on ectomycorrhizal hyphae was found to be strongly dependent on plant-mediated palatability of the fungus. We conclude that the limited available evidence suggests the importance of functional composition of species in determining interactions between plants, nematodes and mycorrhizal fungi, but the degree to which functional redundancy exists within the nematodes and within the mycorrhizal fungi warrants further investigation.