The first report of mycorrhizal inhibition of decomposition was in 1971 and came from ectomycorrhizal Pinus radiata plantations in New Zealand. Authors show that excluding roots and mycorrhizal fungi resulted in net carbon loss, and that the result could not be explained by soil disturbance effects.Gadgil, Ruth L., and P. D. Gadgil. Mycorrhiza and litter decomposition. (1971): 133. The mechanism presented is that ectomycorrhizal fungi can compete with free-living decomposers for nutrients, and thereby limit the rate of total decomposition. Since then there have been several other reports of ectomycorrhizal fungi reducing activity and decomposition rates of free-living decomposers and thereby increasing soil carbon storage.Berg B and Lindberg T. 1980. Is litter decomposition retarded in the presence of mycorrhizal roots in forest soil? Internal Report- Swedish Coniferous Forest Project, Lindahl BD, de Boer W and Finlay RD. 2010. Disruption of root carbon transport into forest humus stimulates fungal opportunists at the expense of mycorrhizal fungi. The ISME Journal, 4: 872-881.McGuire KL et al. 2010. Slowed decomposition is biotically mediated in an ectomycorrhizal, tropical rain forest. Oecologia, 164: 785-795. A theoretical ecosystem model recently demonstrated that greater access to organic nitrogen by mycorrhizal fungi should slow decomposition of soil carbon by free-living decomposers by inducing nutrient limitation.Orwin KH et al. Organic nutrient uptake by mycorrhizal fungi enhances ecosystem carbon storage: a model based assessment. Ecology Letters, 14: 493-502. Koide and Wu (2003) made a strong case that the effect of ectomycorrhizal fungi on reducing decomposition may have more to do with competition for soil water than soil nutrients.Koide RT and Wu T. 2003. Ectomycorrhizas and retarded decomposition in a Pinus resinosa plantation. New Phytologist, 158: 401-407.
