Canadian Science Publishing

We collected mature tanoak ( Lithocarpus densiflorus (Hook. & Arn.) Rehder) roots from five stands to characterize the relative abundance and taxonomic richness of root-associated fungi. Fungi were identified using polymerase chain reaction (PCR), cloning, and sequencing of internal transcribed spacer (ITS) and 28S rDNA. A total of 382 cloned PCR inserts were successfully sequenced and then classified into 119 taxa. Of these taxa, 82 were basidiomycetes, 33 were ascomycetes, and 4 were zygomycetes. Thirty-one of the ascomycete sequences were identified as Cenococcum geophilum Fr. with overall richness of 22 ITS types. Other ascomycetes that form mycorrhizal associations were identified including Wilcoxina and Tuber as well as endophytes such as Lachnum , Cadophora , Phialophora , and Phialocephela . The most abundant mycorrhizal groups were Russulaceae ( Lactarius , Macowanites , Russula ) and species in the Thelephorales ( Bankera , Boletopsis , Hydnellum , Tomentella ). Our study demonstrates that tanoak supports a high diversity of ectomycorrhizal fungi with comparable species richness to that observed in Quercus root communities.

The structure of an ectomycorrhizal community was assessed on a 100-m² plot in a 100-year-old, oligotrophic Norway spruce, Picea abies (L.) Karst., forest in southern Sweden. During the 6-year study (1986–1992) sporocarps were identified and their biomass determined. Late in the fall of 1993, we identified mycorrhizas and estimated their abundance. Forty-eight epigeous, ectomycorrhizal taxa were identified based on the examination of sporocarps. Hygrophorus olivaceoalbus (Fr.:Fr.) Fr. and six species of Cortinarius, i.e., C. acutus (Pers.:Fr.) Fr., C. brunneus (Pers.:Fr.) Fr., C. evernius (Fr.:Fr.) Fr., C. obtusus (Fr.) Fr., C. paleaceus Fr., and C. strobilaceus Moser, were found every year. For the period as a whole, they accounted for 32% of the annual sporocarp biomass. Twenty-one species were observed during 1 year only. Cenococcum geophilum Fr. and Piloderma croceum Erikss. & Hjortst. accounted for 18 and 19%, respectively, of the mycorrhizal abundance of the mycorrhizal root tips examined. Using polymerase chain reaction (PCR) based molecular methods, we were able to distinguish 25 taxa forming mycorrhiza from soil cores covering a total of 22.5 cm² of the forest floor. Twelve of these taxa were identified using a sporocarp or mycelial culture based reference data base containing 25 of the sporocarp-producing species. These 12 species accounted for an average of 74% of the sporocarp biomass. In contrast, their share of the estimated mycorrhizal abundance and biomass was about 30%. At least half of the abundance of the belowground ectomycorrhizal community was accounted for by species that did not produce conspicuous epigeous sporocarps. Ascomycetes accounted for about 20% of the mycorrhizal abundance. Calculations showed that on a per hectare basis there was 8.8 kg of fungal biomass in the form of sporocarps (average annual cumulative production), an estimated 250–400 kg as mycorrhiza (standing crop) and 440 kg in the form of sclerotia of Cenococcum geophilum (standing crop). Key words: ectomycorrhizal community structure, ITS–RFLP, Picea abies.

We examined the species diversity of an ectomycorrhizal community in natural stands of bishop pine (Pinus muricata D. Don) to determine the correspondence between above- and below-ground views of species composition, spatial frequency, and abundance. We addressed this question by simultaneously sampling fruit bodies and ectomycorrhizae over a 4-year period. By using molecular methods based on polymerase chain reaction, we were able to identify the fungal symbionts directly from mycorrhizae in nearly all of the mycorrhizal morphotypes we found. Most species were either rare or low in abundance. Among the common species we observed three patterns: (i) some species, such as Russula xerampelina s.l. and Amanita francheti were well represented both above- and below-ground; (ii) some common fruiting species such as Suillus pungens were rare components belowground; (iii) some species that were common as mycorrhizae were represented poorly or unrepresented in the aboveground fruiting record. The latter was the case for Russula amoenolens, thelephoroid types (i.e., Tomentella sublilacina and thelephoroid-2), and a boletoid type. These results show that (i) the pattern of resource allocation to production of fruit bodies versus ectomycorrhizae varied among species, and (ii) the correspondence between above- and below-ground is imprecise at best at the community level. Keywords: mycorrhizal types, basidiocarps, sporocarps, fungal community, ecology of fungi, PCR, molecular ecology.

Tolypocladium lignicola is described as new. The asymmetrical conidia lodge in the mastax of bdelloid rotifers and germinate to produce assimilative infection hyphae composed of elongate, clavate to turbinate, assimilative cells. Conidial production is prolific in air but suppressed under water.

Haptoglossa humicola (Oomycetes) and Tolypocladium trigonosporum (Hyphomycetes) are described as new endoparasites attacking rotifers, belonging to the genera Adineta and Philodina, in soil. In H. humicola the laterally biflagellate zoospores produce spherical cysts each of which then germinates to form a specialized injection cell. The host is attacked by means of rapid injection of a sporidium through the cuticle. Each sporidium produces a thallus inside the host which at maturity functions as a zoosporangium. In T. trigonosporum, after infection, a network of curved anastomosing fertile hyphae produces a loose shell around the encysted host. Conidia are not produced under water, but in air these fertile hyphae give rise to solitary or clustered phialides and triangulate conidia.

The hyphomycete genus Tolypocladium W. Gams is compared with similar genera possessing swollen phialides and amerosporous conidia borne in slimy heads. Tolypocladium niveum (O. Rostrup) comb. nov. is proposed as the correct name for the type species. Cephalosporium balanoides Dreschler and Verticillium microsporum Jaap are redisposed in Tolypocladium, and two new species of Tolypocladium are described from tundra soils.

A new species, Tolypocladium parasiticum, is described as endoparasitic on the rotifer host Adineta. Unlike most other known Hyphomycetes parasitic on rotifers, conidia are produced underwater. Infection is initiated by conidia lodging in the lower gullet near the mastax of the host. Conidiogenous cells (phialides) arise either directly from the host body or in clusters from short, simple conidiophores. This species produces solitary terminal resting spores with an unusual nodular appearance.

The net CO₂ exchange responses of Cladonia mitis, C. rangiferina, and C. uncialis from the Wisconsin Pine Barrens to irradiance, thallus temperature, and thallus relative water content were statistically compared for fall, spring, and summer. The absolute net photosynthetic rate of C. rangiferina exceeded that of C. uncialis under essentially all conditions and in all seasons; C. mitis's absolute net photosynthesis fluctuated with the seasons between these two contrasting species. Cladonia mitis showed significant intraspecific seasonal variation in net photosynthetic responses to temperature and irradiance. Cladonia rangiferina showed significant seasonal variation in dark respiratory response to temperature. Cladonia uncialis showed no significant intraspecific seasonal variation in net CO₂ exchange responses. Significant interspecific differences in net CO₂ exchange responses centered on the net photosynthetic responses to thallus temperature and relative water content.Despite its low net photosynthetic rates, C. uncialis is the most prevalent lichen in the Wisconsin Pine Barren ground-layer community. We attribute this not to broad physiological tolerance, but to its significantly slower drying rate. Lichens photosynthesize only when wetted. Cladonia uncialis photosynthesizes at generally lower rates than C. mitis or C. rangiferina, but it photosynthesizes longer under comparable environmental drying regimes. This and other aspects of the physiological ecology of the three species are discussed in relation to microdistribution and microhabitats within the Wisconsin Pine Barrens.

Forest soils and litter in the vicinity of a large nickel–copper smelter at Sudbury, Ont. are known to be contaminated with a variety of heavy metals. In view of this, studies were carried out to determine if forest litter decomposition processes have been affected. The effects of nickel and copper on the decomposition of forest litter were investigated using a variety of techniques in which contaminated and control sites were compared. At contaminated sites an increase in litter standing crop was found. This was related to lower rates of litter decomposition at these sites, as evidenced by reduced rates of breakdown of litter in mesh bags, compared with uncontaminated sites. Lower rates of CO₂ flux and acid phosphatase activity were also found at the contaminated sites. In a laboratory experiment, the addition of copper and (or) nickel to a homogenate of leaf litter was shown to depress the rate of dry weight loss and CO₂ flux. Negative effects commenced at metal concentrations comparable to those observed in litter at contaminated sites in the field.

Accumulations of six metals (Cu, Ni, Mn, Al, Fe, and Ca) were analysed in peat and water for 18 peatlands east northeast of Falconbridge, Ontario, Canada. The peatlands had a minimum of 30 cm accumulation of peat, < 10 μg mL⁻¹ Ca²⁺ in the water, and were from a variety of physiognomic dominance types. Significant correlations existed between the distance from smelting operations and the concentrations of Cu and Ni in the peat and water. Levels of Mn, Fe, and Ca were not related to distance. The vegetation was analysed on 11 of the 18 peatlands. With the exception of the two sites closest to the smelter, all are low shrub peatlands, dominated by Chamaedaphne calyculata. Effects on the vegetation range from severe within 2 km of the smelter to minimal at 30 km. Sphagnum species that normally dominate the moss layer of these peatlands begin to appear at approximately 12 km from the smelter and are found almost exclusively in the moat area. With increasing distance and decreasing concentrations of Cu and Ni, conditions gradually permit growth of the oligotrophic Sphagnum species. Beyond 30 km, Sphagnum dominates all portions of the peatlands.