Exploration types of ectomycorrhizae - A proposal to classify ectomycorrhizal mycelial systems according to their patterns of differentiation and putative ecological importance

There is a need to quantify and qualify the ability of ectomycorrhizae to i mprove tree growth and nutrition and, in particular, to define criteria to classify ectomycorrhizae with respect to ecologically relevant features. Wh ereas the numbers of ectomycorrhizae and morphotypes give useful informatio n when related to root biomass, root length or soil volume, the development and differentiation of the extramatrical mycelium may represent important predicative features relevant to the ecological classification of ectomycor rhizae. Here, different exploration types of ectomycorrhizae are distinguis hed based on the amount of emanating hyphae or the presence and differentia tion of rhizomorphs. Their putative ecological importance is discussed.