Abstract:
In this study we analyzed the spatial
structure of ectomycorrhizal fungi present in the soils
as resistant propagules (e.g. spores or sclerotia) in
a mixed-conifer forest in the Sierra Nevada, California.
Soils were collected under old-growth Abies spp.
stands across approximately 1 km and bioassayed with
seedlings of hosts that establish best in stronger light
(Pinus jeffreyi) or that are shade-tolerant (Abies
concolor). Ectomycorrhizal fungi colonizing the roots
were characterized with molecular techniques (ITSRFLP
and DNA sequence analysis). Wilcoxina, five
Rhizopogon species and Cenococcum were the most
frequent of 17 detected species. No spatial structure
was detected in the resistant propagule community as
a whole, but P. jeffreyi seedlings had higher species
richness and associated with seven Rhizopogon species
that were not detected on A. concolor seedlings. We
drew two conclusions from comparisons between this
study and a prior study of the ectomycorrhizal
community on mature trees in the same forest:
(i) the resistant propagule community was considerably
simpler and more homogeneous than the
active resident community across the forest and
(ii) Cenococcum and Wilcoxina species are abundant
in both communities.
