Ectomycorrhizal fungi in Lyman Lake Basin: a comparison between primary and secondary successional sites

The results of eight years of study of the ectomycorrhizal macrofungi at th e subalpine Lyman Lake Basin (Glacier Peak Wilderness area in the North Cas cade Mountains, Washington, USA) are reported. The basin was divided into t hree sites: the primary successional glacier forefront vs two secondary suc cessional habitats (subalpine parkland and old-growth montane Tsuga mertens iana-Abies amabilis). The 145 collections of ectomycorrhizal fungi obtained represented 68 species, 25 genera, 14 families and 7 orders. The Cortinari aceae was the most species-rich family with 25 species. Cortinarius was the most species-rich genus with 17 species. The two secondary successional si tes shared 12.1% of the species; while the primary successional site shared only 2 and 5.1%, respectively, with the two secondary successional sites. No ectomycorrhizal species occurred on all three sites. The secondary succe ssional sites shared 7 species (Boletus edulis, Elaphomyces granulatus, Hyd notrya variiformis, Rhizopogon subsalmoneus, Rh. vulgan's, Russula silvicol a and Thaxterogaster pingue) while the primary successional site shared two species with the parkland (Suillus aeruginascens and Su. cavipes) and only one with the montane site (Inocybe lacera). Fifty-eight species occurred a t only one site. These data show that the communities of ectomycorrhizal fu ngi differ between the primary and secondary successional sites. We hypothe size that fungal life history strategies and habitat characteristics are mo re important determinants of succession of mycorrhizal fungi than host age or physiology as suggested by the relatively simple early- and late-stage m odel.