Commentary Uncommon ectomycorrhizal

networks: richness and distribution of Alnus-associating ectomycorrhizal fungal communities The level of specificity is a key evolutionary and ecological parameter of any symbiotic interaction. Where diverse classes of mutualists interact, extracting the drivers of spatial–temporal variation in community composition is also fundamental to understanding the interaction. Ectomycorrhizal (EM) plants and fungi typically associate with many symbionts both as individuals and across a species ’ range. Trappe (1977) estimated that Pseudotsuga menziesii is compatible with some 2000 species of EM fungi, an impressively high number that has stood the test of time but could be revisited. At the low end among autotrophic plants is the genus Alnus. Although it is known that the EM fung