STUDIES ON THE ECOLOGY OF POST-FIRE PEZIZALES (ASCOMYCETES): PATHOGENICITY, BIOTROPHIC ASSOCIATIONS, AND SUBSTRATE HYDROLYSIS PATTERNS.

摘要

The post-fire Pezizales are a group of Ascomycetes that are commonly found fruiting on burned substrates. The species discussed in this study were collected from burned forest habitats. Many factors enable the post-fire Pezizales to colonize burned substrates, including tolerance of high pH levels. However, little is known about the ecological role of these fungi in the post-fire environment. The objectives of this study were: to collect, culture, and observe life-history attributes of post-fire Pezizales; to test species for biotrophic associations (eg. pathosis, mycorrhiza-formation) with seeds, germinants, and seedlings of lodgepole pine (Pinus contorta); and to test isolates for ability to hydrolyze major soil component substrates. Fourteen genera, representing 31 species, of post-fire Pezizales were collected from burned sites. Life-history attributes of post-fire species generally correlated with their time of appearance in the post-fire succession. Species with colonizing attributes appeared early and species with attributes that favor persistence appeared later in the succession. Many post-fire Pezizales are associated with the breakdown of roots that remain after burning of the above-ground vegetation. The early colonizing species (Anthracobia spp., Ascobolus carbonarius, and Trichophaea abundans) attack the fine root biomass. Later appearing species (Geopyxis carbonaria, Tricharina praecox var. intermedia, and Morchella elata) are involved in the decay of woody root tissues of dead and dying trees. Pyropyxis rubra and Rhizina undulata are pathogenic species and undoubtedly attack trees that are weakened by fire damage. A few species formed balanced biotrophic associations: Sphaerosporella brunnea forms ectendomycorrhizae, and Trichophaea hemisphaerioides forms a pathogenic/symbiotic type of association. Peziza spp. appear to be saprophytes involved in the breakdown of litter or humus. The ecological role of Pulvinula archeri and Scutellinia spp. could not be determined. The majority of species are opportunistic decomposers of facultative biotrophs adapted to the transient, but regularly perturbed, post-fire environment.