Sporocarp Production Research Articles

Interactions among Prescribed Fire, Soil Attributes, and Mycorrhizal Community Structure at Crater Lake National Park, Oregon, USA

We identified relationships between prescribed burn treatments and selected soil and fuel attributes on mycorrhizal fungus fruiting patterns in an old-growth ponderosa pine (Pinus ponderosa) and white fir (Abies concolor) stand in Crater Lake National Park, Oregon, USA. Three prescribed burn treatments (early spring, late spring, and fall burns) plus non-burned controls were applied to 24 ∼3 ha units in 2002. We sampled mycorrhizal fungus sporocarp production in the spring and fall in the ensuing three years, and collected data on surface fuels, soil C and N concentrations, δ13C and δ15N signatures, pH, and mineral soil bulk density. A gradient of C:N ratios and other soil attributes across the study area facilitated separation of the effect of fire from the effects of soil attributes on fungal fruiting patterns. Distinct guilds of fungal indicator species were identified, correlating more closely with soil C:N ratios than prescribed burn treatments. Although other habitat attributes (such as fuel levels) were correlated with C:N ratios, the C:N ratios were the most consistent predictor of fungal fruiting patterns. The fall burn treatment did reduce soil C:N ratios, and most of the fall burned units produced the fungal indicator species associated with lower C:N ratios, but the same fungal indicator species also fruited in the non-burned control units with lower C:N ratios. The spring burn treatments did not differ significantly from non-burned controls in fungal fruiting patterns or C:N ratios. Fall burn treatment units produced significantly fewer fungal species and collections than spring burn units, but did not differ significantly in fungal diversity and abundance from non-burned controls.

Productivity and community structure of ectomycorrhizal fungal sporocarps under increased atmospheric CO2 and O3

Sporocarp production is essential for ectomycorrhizal fungal recombination and dispersal, which influences fungal community dynamics. Increasing atmospheric carbon dioxide (CO2) and ozone (O3) affect host plant carbon gain and allocation, which may in turn influence ectomycorrhizal sporocarp production if the carbon available to the ectomycorrhizal fungus is dependant upon the quantity of carbon assimilated by the host. We measured sporocarp production of ectomycorrhizal fungi over 4 years at the Aspen FACE (free air CO2 enrichment) site, which corresponded to stand ages seven to 10 years. Total mean sporocarp biomass was greatest under elevated CO2, regardless of O3 concentration, while it was generally lowest under elevated O3 with ambient CO2. Community composition differed significantly among the treatments, with less difference in the final year of the study. Whether this convergence was due to succession or environmental factors is uncertain. CO2 and O3 affect ectomycorrhizal sporocarp productivity and community composition, with likely effects on dispersal, colonization and sporocarp-dependent food webs.

Spatial distribution of sporocarps of stipitate hydnoid fungi and their belowground mycelium

Interest in stipitate hydnoid fungi of the genera Bankera, Hydnellum, Phellodon and Sarcodon has increased due to the decline in numbers of sporocarps in Europe. Conservation of these fungi is hindered by a lack of understanding of their basic ecology. In particular, a better understanding of their belowground ecology is required. Real-time PCR in conjunction with spatially explicit sampling was used to quantify the relationship between sporocarps and mycelium of Hydnellum peckii and Phellodon tomentosus. Species-specific DNA of the target species was quantified in 100 soil samples collected on a 360 x 360 cm grid at five locations where sporocarps were present. All sporocarps within the grid and up to 2 m around the grid were mapped. Sporocarp production did not occur over the whole extent of the belowground mycelium of these two species, and mycelium extended up to 330 cm away from the immediate site of sporocarp production. Spatial analyses using Kernel-smoothing and Moran's I correlograms showed that, with a single exception, there was no quantitative relationship between sporocarp distribution and the belowground abundance of mycelium. These findings have important implications for the conservation of this rare group of fungi.

Towards a global view of ectomycorrhizal ecology

Towards a global view of ectomycorrhizal ecology

Microbial activity and soil respiration under nitrogen addition in Alaskan boreal forest

AbstractClimate warming could increase rates of soil organic matter turnover and nutrient mineralization, particularly in northern high‐latitude ecosystems. However, the effects of increasing nutrient availability on microbial processes in these ecosystems are poorly understood. To determine how soil microbes respond to nutrient enrichment, we measured microbial biomass, extracellular enzyme activities, soil respiration, and the community composition of active fungi in nitrogen (N) fertilized soils of a boreal forest in central Alaska. We predicted that N addition would suppress fungal activity relative to bacteria, but stimulate carbon (C)‐degrading enzyme activities and soil respiration. Instead, we found no evidence for a suppression of fungal activity, although fungal sporocarp production declined significantly, and the relative abundance of two fungal taxa changed dramatically with N fertilization. Microbial biomass as measured by chloroform fumigation did not respond to fertilization, nor did the ratio of fungi : bacteria as measured by quantitative polymerase chain reaction. However, microbial biomass C : N ratios narrowed significantly from 16.0 ± 1.4 to 5.2 ± 0.3 with fertilization. N fertilization significantly increased the activity of a cellulose‐degrading enzyme and suppressed the activities of protein‐ and chitin‐degrading enzymes but had no effect on soil respiration rates or 14C signatures. These results indicate that N fertilization alters microbial community composition and allocation to extracellular enzyme production without affecting soil respiration. Thus, our results do not provide evidence for strong microbial feedbacks to the boreal C cycle under climate warming or N addition. However, organic N cycling may decline due to a reduction in the activity of enzymes that target nitrogenous compounds.

Influence of soil temperature and precipitation depth on the biomass production of fruiting bodies of macromycetes in a submountain beech forest stand

The paper deals with research on the biomass production of fruiting bodies of macromycetes in a submountain beech stand in dependence on selected climatic variables. The study was carried out at the Ecological Experimental Site (EES) Kremnické vrchy (Central Slovakia) in 2003 and 2004. The biomass production of sporocarps on the EES plots in the two study years was different (5.81 kg/ha of fresh biomass of sporocarps in 2003 and 39.95 kg/ha in 2004) due to better ecological and climatic conditions and higher abundance of sporocarps in 2004. It is necessary to mention that these values reflect the overall status of mycocoenoses on the plot. Unfavourable microclimate conditions and poor species composition of beech monocultures can be considered to be the main factors adversely influencing mycocoenoses in forest stands of the kind.

Productivity of ectomycorrhizal and selected edible saprotrophic fungi in pine forests of the pre-Pyrenees mountains, Spain: Predictive equations for forest management of mycological resources

Edible and medicinal fungi have become increasingly important non-wood forest products in Spanish forests. Annual mushroom collections increase the economic value of forests and provide income to local collectors and marketers. Most of the species are ectomycorrhizal fungi that are essential for seedling establishment and long-term nutrition of the trees. Due to the economic depression in the local wood markets of the Pyrenees, forest managers are evaluating alternatives to timber management for these forests. Information on the biology and ecology of these fungi, especially on factors influencing their productivity, are needed to properly manage and enhance this natural resource. In 1997, 23 study plots of 400 m 2 were randomly placed in Pinus nigra, Pinus sylvestris and Pinus halepensis forests of Solsonés County, Catalonia, Spain, to monitor the production of ectomycorrhizal and edible forest fungi in relation to climate and forest stand variables. The 5-year inventory (1997 through 2001) included weekly sporocarp collections from September through December to estimate the annual county production and to examine production according to forest species, edibility and commercial status. Annual county sporocarp production was 29.4 kg ha −1, of which 6.2 kg ha −1 are edible marketed species and 5.4 kg ha −1 are edible non-marketed species. Regression analysis of climate and forest stand variables reveal significant correlations with sporocarp production data. The best climate equation ( R 2 = 0.66; P < 0.001) for annual sporocarp estimation was based on the difference between monthly mean precipitation and accumulated monthly mean evapotranspiration for the months of September and October, and the monthly mean minimum soil temperature in August. Stand age was not a good explicative variable for total sporocarp production, and was negatively correlated ( R 2 = 0.23; P < 0.021) with production of edible species.

Mycorrhizal inoculum potential of arbuscular mycorrhizal fungi in soils irrigated with wastewater for various lengths of time, as affected by heavy metals and available P

Sewage water is widely used for irrigation in dry countries, but the practice can lead to the accumulation of heavy metals in the soil and consequent poisoning of the soil's microorganisms. The area irrigated with sewage water in the Mezquital Valley in central Mexico has steadily expanded during the last 100 years, and it provides the opportunity to assess the effects of the practice on the mycorrhiza in particular. We sampled the topsoil of the two main kinds of soil, Vertisol and Leptosol, in fields irrigated for 5, 35, 65 and 95 years in the Valley. We measured the concentrations of zinc, lead, copper and cadmium, all of which appeared to have increased linearly with time. We also determined the abundances of arbuscular mycorrhizal morphotypes in the soil both at the time of sampling and after incubation in association with Allium cepa L. in the greenhouse. Spores decreased in abundance with increasing duration of irrigation in the Vertisol, whereas in the Leptosol the numbers after only 5 years of irrigation were small, increased after 35 years of irrigation and decreased again thereafter. In the greenhouse the production of spores and sporocarps was maximal in soil irrigated for between 35 and 65 years, as were the intraradical hyphae, spores and vesicles. Glomus species dominate the morphotypes, and the spores of Glomus mosseae were the most abundant in both soils and after all times. The total root colonization potential seemed unaffected by duration of irrigation, and was substantially greater in the Leptosol than in the Vertisol. However, species of the Glomus genus tend to dominate over other genera as irrigation proceeds, since Glomus species spread not only by spores, but also by roots. We conclude that irrigation with sewage water in the Mezquital Valley is decreasing the mycorrhizas’ diversity in the long term.

A simple method to assess macrofungal sporocarp biomass for investigating ecological change

The methodologies used for studying macrofungal communities are an eclectic assemblage of many different and unstandardized approaches. In this study we propose a simple, nondestructive but still informative method to assess fungal sporocarp biomass in forested areas. We use the number of fruiting bodies found in the surveyed plot, and data on cap diameter of the species from the literature to calculate a cap area index. We show that this index very strongly correlates with the measured total dry mass of the species obtained from the same plot. We point out that the cap area index provides a more accurate estimation of the epigeous fungal sporocarp biomass than do the species sporocarp numbers. This new methodology allows the spatiotemporal distribution of a fungal community in an ecosystem to be followed. Since sporocarp production responds much more sensitively to environmental changes than does the fine-root vegetative ectomycorrhizal community, it may more quickly reflect whether an ecosystem has been perturbed. It will also allow us to collect data on saprotrophic species. A sporocarp survey can be useful for detecting early changes in the habitat and environment, and give an easily applicable method for conservation biology and ecosystem management.

Spatial distribution of sporocarp production of ECM fungi Amanita ponderosa Malençon &amp; R. Heim during six consecutive years at a holm-oak forest (dehesa) in the Sierra de Aracena (Huelva)

Number and location of Amanita ponderosa Malençon &amp; R. Heim sporocarps was followed through six years in a 3 ha holm-oak forest located in the Sierra de Aracena y Picos de Aroche Natural Park (Huelva), at the Southwest of Spain. The data indicated that patches of sporocarp production showed a very similar shape each year, but some spots showed differences seeming crop alternance or mast years. This species only fructifies in spring, being the fruiting period from 6 to 8 weeks, what coincides with the increasing of air-temperature from mid February to April. Differences in fruiting period length and total sporocarp production are related to rainfall and temperature. Results suggest that rainfalls at the end of summer and early autumn are crucial for the next spring fruiting, but rainfalls during fruiting period seem to have less influence in sporocarp production. During the sporocarp production period, it was related to soil temperature.

Carbon and nitrogen elemental and isotopic patterns in macrofungal sporocarps and trees in semiarid forests of the south‐western USA

Summary Previous studies in humid forests have shown that the 13C and 15N isotopic composition differs between ectomycorrhizal (ECM) and saprotrophic (SAP) fungi, and that this ECM–SAP ‘divide’ may provide a useful tool for evaluating fungal trophic status. We evaluated whether this method could delineate the trophic status of fungi in two semiarid, temperate forests of the south‐western USA. This technique could be particularly valuable in arid regions where the functional roles of fungi can be difficult to assess because of infrequent sporocarp production. Our data were consistent with the existence of an ECM–SAP divide, although δ13C values were more useful than δ15N values in separating trophic status. Saprotrophic fungi consistently had higher δ13C values than their presumed substrates; however, the degree of 15N enrichment in SAP sporocarps was highly variable. Comparison of 11 sporocarp species common to both sites showed that δ15N values were higher in one of the forests, even though the δ15N values of foliage from common understorey and overstorey trees were similar between forests. We conclude that assessment of the isotopic compositions of fungal sporocarps and their substrates is helpful for elucidating ecological relationships in semiarid forests.

The ectomycorrhizal symbiosis: life in the real world

Ectomycorrhizas (ECM) are dual organs formed between the terminal feeder roots of many plant species and certain soil fungi. The species richness and taxonomic diversity of ECM symbionts is impressive: ca. 7-10,000 fungal and ca. 8,000 plant species may be capable of forming ECM. The latter are the dominant components of forest and woodland ecosystems over much of the earth's surface. The obligate nature of the symbiosis for ECM fungi has been brought into question by reports that some species produce sporocarps under field conditions in the absence of a host plant. We suggest that there is no unequivocal evidence to support this. The spread of tree roots is often underestimated and small, overlooked hosts such as dwarf Salix spp or sedges may explain the appearance of ECM sporocarps in vegetation apparently devoid of ECM hosts. Compared to plant material, the sporocarps of ECM fungi contain high concentrations of N and P. We show that it would take between 3 and 14 million mycorrhizal tips, or 1800 km of hyphae, to supply the N in one sporocarp of Boletus edulis . The mantle formed by the fungus over the root tip is the likely site of storage for the N and P required for sporocarp production, and we discuss the chemical and structural mechanisms developed on mantles by ECM fungi to defend this resource against fungivory.

Effects of nitrogen with and without acidified sulphur on an ectomycorrhizal community in a Sitka spruce ( Picea sitchensis Bong. Carr) forest

This preliminary study investigated the effects of enhanced nitrogen (NH 4NO 3 at 48 kg ha −1 y −1), sulphur (Na 2SO 4 at 50 kg ha −1y −1), acidified nitrogen and sulphur (H 2SO 4 + NH 4NO 3) at pre-stated doses (pH 2.5), and acidified nitrogen and sulphur deposition at double these doses on the ectomycorrhizal community associated with a 13-year-old Sitka spruce ( Picea sitchensis) forest. Sulphur deposition had little impact on below ground ectomycorrhizal diversity, but stimulated sporocarp production. Nitrogen inputs increased below ground colonisation compared to acidified nitrogen and sulphur, largely due to an increase in Tylospora fibrillosa colonisation. Sporocarp production and ectomycorrhizal root colonisation by Lactarius rufus were reduced in the nitrogen treated plots. These observations suggest that nitrogen deposition to a young plantation may suppress ectomycorrhizal fungi producing large sporocarps. It is proposed that enhanced nitrogen deposition increases ectomycorrhizal nitrogen assimilation, consuming more carbon and leaving less for extrametrical mycelium and sporocarp development.

Below‐ground responses of silver birch trees exposed to elevated CO2 and O3 levels during three growing seasons

AbstractField‐growing silver birch (Betula pendula Roth) clones (clone 4 and 80) were exposed to elevated CO2 and O3 in open‐top chambers for three consecutive growing seasons (1999–2001). At the beginning of the OTC experiment, all trees were 7 years old. We studied the single and interaction effects of CO2 and O3 on silver birch below‐ground carbon pools (i.e. effects on fine roots and mycorrhizas, soil microbial communities and sporocarp production) and also assessed whether there are any clonal differences in these below‐ground CO2 and O3 responses. The total mycorrhizal infection level of both clones was stimulated by elevated CO2 alone and elevated O3 alone, but not when elevated CO2 was used in fumigation in combination with elevated O3. In both clones, elevated CO2 affected negatively light brown/orange mycorrhizas, while its effect on other mycorrhizal morphotypes was negligible. Elevated O3, instead, clearly decreased the proportions of black and liver‐brown mycorrhizas and increased that of light brown/orange mycorrhizas. Elevated O3 had a tendency to decrease standing fine root mass and sporocarp production as well, both of these O3 effects mainly manifesting in clone 4 trees. CO2 and O3 treatment effects on soil microbial community composition (PLFA, 2‐ and 3‐OH‐FA profiles) were negligible, but quantitative PLFA data showed that in 2001 the PLFA fungi : bacteria‐ratio of clone 80 trees was marginally increased because of elevated CO2 treatments. This study shows that O3 effects were most clearly visible at the mycorrhizal root level and that some clonal differences in CO2 and O3 responses were observable in the below‐ground carbon pools. In conclusion, the present data suggests that CO2 effects were minor, whereas increasing tropospheric O3 levels can be an important stress factor in northern birch forests, as they might alter mycorrhizal morphotype assemblages, mycorrhizal infection rates and sporocarp production.

Persistence strategy of Salvinia auriculata Aublet in temporary ponds of Southern Pantanal, Brazil

We examined the effects of drought, flooding periods and plant density on the persistence strategies of Salvinia auriculata in temporary ponds in the Southern Pantanal. Ramets were found to bear sporocarps during the dry rather than during the flooding season. In high-density conditions the frequency of ramets producing new ramets did not differ between drought and flood. However, during the flooding period, the frequency of production of new ramets under low-density conditions was higher than under high plant densities. A greenhouse experiment showed that the number of sporocarps produced under a high-density treatment was greater than when plant density was kept low. The individual mass of each sporocarp was also greater for the high-density treatment. In contrast, the number of new ramets produced under the low-density treatment was greater than at high densities, as was ramet mass. Abundant sporocarp production in S. auriculata was found to be associated with habitats that dry up. Such flexibility of life history pattern enhances survival in widely fluctuating environments, such as the temporary shallow ponds in the Pantanal.

The relationship between forest age and aspect on the production of sporocarps of ectomycorrhizal fungi in Pinus sylvestris forests of the central Pyrenees

Due to increasing economic interest in forest fungi as important non-wood forest products, autumn mushrooms from Pinus sylvestris forests of the Spanish Pyrenees were collected for three consecutive years to examine the relationships between forest age and aspect on the sporocarp production of epigeous edible and ectomycorrhizal fungi. Fresh weight, dry weight and number of sporocarps were recorded from thirty-six 100 m 2 forest plots with a range of seven age classes and four aspects. The 9073 sporocarps collected represent 164 taxa and 34 genera. Age class was observed to be an influential factor for 21 taxa and aspect for 7 taxa. We gave special attention to edible and marketed mushrooms, particularly Lactarius deliciosus, which is the most widely collected species from these forests. Edible marketed-species comprise 20% of the total fresh weight yield. Species richness and distribution are presented, providing a baseline inventory for this forest community. There is a positive relationship between sporocarp yield (fresh weight, dry weight or number of sporocarps) and species richness for individual plots.

Response of ectomycorrhizal fungus sporocarp production to varying levels and patterns of green-tree retention

Forest management activities can reduce ectomycorrhizal fungus diversity and forest regeneration success. We examine contrasts in structural retention as they affect sporocarp production of ectomycorrhizal fungi (EMF)—a functional guild of organisms well suited as indicators of disturbance effects on below-ground ecosystems. Our results are from an experiment that tests the biodiversity assumptions behind current guidelines for ecosystem management. Ours is the first study complete with pre-treatment data that examines the effects of silvicultural manipulations on both epigeous (mushroom) and hypogeous (truffle) sporocarp production by EMF. We tested the effects of two patterns (aggregated [A], dispersed [D]) and four levels (100, 75, 40, and 15%) of green-tree retention on standing-crop sporocarp biomass for spring and fall fruiting seasons. This study employed a randomized block design that replicated six retention treatments in three locations (blocks). A total of 150 mushroom taxa and 58 truffle taxa were identified from the sample plots. Before treatment, the total number of mushroom taxa for each treatment ranged from 58 to 72 while the total number of truffle taxa ranged from 22 to 29. The pre-treatment condition was characterized by mushroom and truffle total fall biomass exceeding total spring biomass in two of three blocks. Although experimental units within blocks were selected for apparent similarity, our results show that uniformity of EMF populations in forests cannot be inferred from stand structure alone. During the post-treatment sample period, the number of mushroom taxa detected in the 100% retention decreased by 34% while the number of truffle taxa increased by 20%. The number of taxa was reduced most in the 15%D treatment followed by the 15%A treatment. The 75%A retention treatment showed the least reduction in number of fruiting taxa. After treatment, sporocarp production declined in all treatments, but these effects varied by season and treatment. Sporocarp production was nearly eliminated from the 15%A retention treatment. Mushroom and truffle production were significantly reduced in the 15%D treatment, though spring truffle biomass was maintained at 33% of the pre-treatment value. No treatment effect was detected on the fall mushroom or truffle standing crop in the 40%D treatment. Our results lend support to the use of dispersed green-tree retention in combination with aggregated retention when maintaining sporocarp production is a goal. Such a mix would ameliorate the effects of clearcutting as demonstrated in this study and may maintain higher levels of sporocarp production in the aggregates by reducing edge effects.

Macrofungus communities correlate with moisture and nitrogen abundance in two old-growth conifer forests, Olympic National Park, Washington, USA

We characterized the epigeous macrofungus communities in two old-growth conifer forests by collecting sporocarps. Despite the similarity in dominant tree species in the two forests, the macrofungus communities were very different. At the drier, nitrogen-poor Deer Park area, the macrofungi were dominated by ectomycorrhizal species in the genera Cortinarius, Tricholoma, Hydnellum, Suillus, and Sarcodon. At the wetter, higher nitrogen Hoh Valley, the macrofungi were characterized by ectomycorrhizal species in different genera, such as Inocybe, Russula, Amanita, Boletus, and Phaeocollybia, and saprotrophic fungi accounted for a greater proportion of the community. Species richness was similar at the two areas, but sporocarp production was much higher at Deer Park. We propose that (i) these community differences developed over a long time; (ii) they are largely related to differences in ecosystem moisture and nitrogen abundance; and (iii) within the ectomycorrhizal fungi, possible causal mechanisms involve mycelial morphology and carbon allocation within the symbioses. The apparent response to relatively small but presumably long-term differences in nitrogen abundance suggests that sporocarp production by macrofungi could be an effective bioindicator and should be considered in determination of critical loads for atmospheric nitrogen deposition to temperate and boreal forests.Key words: critical nitrogen loads, ectomycorrhizal fungi, macrofungi, macrofungus communities, nitrogen, old-growth conifer forests.

Long‐term increase in nitrogen supply alters above‐ and below‐ground ectomycorrhizal communities and increases the dominance ofRussulaspp. in a temperate oak savanna

• Here we examine the effects of increased nitrogen (N) supply on the ectomycorrhizal fungal communities of a temperate oak savanna. • In a 16-yr N-addition experiment in which replicate 1000m2 plots received 0, 5.4 or 17gNm-2 yr-1 , ectomycorrhizal sporocarp production was measured in the 14th, 15th and 16th year of fertilization. Ectomycorrhizal fungi (EMF) colonizing roots were examined by morphotyping-PCR-RFLP and sequence analysis in the 14th and 15th year of fertilization. • Total sporocarp richness was reduced by >50% in both fertilization treatments in all 3yrs, whereas Russula spp. produced approx. five times more sporocarps with 17gNm-2 yr-1 . Below-ground, treatment-scale species richness and species area curves were lower with 17gNm-2 yr-1 but richness, diversity indices and evenness at smaller spatial scales were not. Dominant fungi colonizing roots included Cenococcum geophilum, common in all treatments, Cortinarius spp., dominant in unfertilized plots, and Russula spp., dominant with 17gNm-2 yr-1 . • Communities of EMF in this temperate deciduous ecosystem responded to N addition similarly to those of coniferous ecosystems in that increased N supply altered EMF diversity and community composition but differently in that dominance of Russula spp. increased.

Ectomycorrhizal sporocarp succession and production during early primary succession on Mount Fuji

Ectomycorrhizal sporocarp succession and production during early primary succession on Mount Fuji