Soil microbiome has a pivotal role in ecosystem functioning, yet little is known about its build-up from local to regional scales. In a multi-year regional-scale survey involving 1251 plots and ...long-read third-generation sequencing, we found that soil pH has the strongest effect on the diversity of fungi and its multiple taxonomic and functional groups. The pH effects were typically unimodal, usually both direct and indirect through tree species, soil nutrients or mold abundance. Individual tree species, particularly
Pinus sylvestris
,
Picea abies
, and
Populus x wettsteinii
, and overall ectomycorrhizal plant proportion had relatively stronger effects on the diversity of biotrophic fungi than saprotrophic fungi. We found strong temporal sampling and investigator biases for the abundance of molds, but generally all spatial, temporal and microclimatic effects were weak. Richness of fungi and several functional groups was highest in woodlands and around ruins of buildings but lowest in bogs, with marked group-specific trends. In contrast to our expectations, diversity of soil fungi tended to be higher in forest island habitats potentially due to the edge effect, but fungal richness declined with island distance and in response to forest fragmentation. Virgin forests supported somewhat higher fungal diversity than old non-pristine forests, but there were no differences in richness between natural and anthropogenic habitats such as parks and coppiced gardens. Diversity of most fungal groups suffered from management of seminatural woodlands and parks and thinning of forests, but especially for forests the results depended on fungal group and time since partial harvesting. We conclude that the positive effects of tree diversity on overall fungal richness represent a combined niche effect of soil properties and intimate associations.
Inonotus obliquus, a well-known forest fungal pathogen, started gaining attention for its potential medicinal uses. Known as Chaga, the fungus has become prominent due to the bioactive compounds ...present in its conks. Forest owners are cultivating it to produce conks as a source of non-timber profit. However, not much is known about the natural occurrence of this pathogen, its formation of conks, the extent of decay in the infected trees, and the distribution of its basidiospores. Across 80 forest stands in Estonia dominated by Betula pendula, B. pubescens, Alnus incana, and A. glutinosa, the conks of I. obliquus were documented in 17 stands. The conks were more common in continental Estonia compared to the western islands. Among 800 randomly chosen trees, I. obliquus conks were documented on ten trees. Additionally, an asymptomatic I. obliquus infection was detected in one tree. After two years of spore trapping, I. obliquus basidiospores were detected only on four occasions, between the end of July and the beginning of September, and only at night. The proportion of rot damage in the total volume of model tree wood ranged from 8.6% to 58.5%. For fast and reliable detection of I. obliquus, TaqMan species-specific qPCR primers were developed and tested.
•The rot damage caused by I. obliquus ranged from 8.6% to 58.5% of the host tree volume.•obliquus propagates its basidiospores only at night.•The basidiospores were released from the end of July to the beginning of September.•The conks of I. obliquus are equally likely to be found in Betula and Alnus stands.•1.25% of host trees were having I. obliquus conks.
Interest in the cultivation of mushrooms, including medicinal mushrooms like Chaga (Inonotus obliquus) has increased in recent years. To provide commercial cultivators with vigorous and productive ...strains of I. obliquus, 38 strains were isolated from the conks in Estonia and Finland. The growth rates of these isolates were determined on Malt Extract Agar (MEA), and on wood sticks of Betula pendula, B. pubescens, Alnus incana and A. glutinosa. Growth rates differed for the various isolates, depending on temperature as well as substrate. On the MEA at 9°C the fastest-growing strain of I. obliquus was PAT21061, at 18°C PAT22871 and at 22°C PAT21058. On B. pendula, the I. obliquus strain, PATKJ180 had the highest growth rate; on B. pubescens, PAT21061; on A. glutinosa, PATKA880; and on A. incana, PATKA2679 exhibited the highest growth rate. But the growth rate characteristics of I. obliquus were not correlated with the host species origin of the fungus isolate. Still, the ability of strains to form conks is unknown and needs to be tested in vivo. Because I. obliquus grows faster in Betula wood than Alnus, the use of Betula wood for producing inoculation dowels is recommended in order to shorten the production time.
•Positive effect of stump removal on the height growth of the trees was revealed.•Stump removal had no effect on the nutritional status of the needles of young trees.•Positive trend of stump removal ...on twig and needle parameter revealed.•Stump removal had no effect on the spread of Heterobasidion sp., Armillaria sp.•The main causal agent of root rot on all the sampling sites was H. parviporum.
Stumpwood as a resource of renewable bioenergy has considerable potential in the Nordic and Baltic countries. So far, however, it has largely been left unutilised in Estonia. This study reports the results of the height growth, needle and twig traits, and Heterobasidion sp. and Armillaria sp. infection in emerging Norway spruce (Picea abies) stands after stump harvesting. After six and eight growing seasons, a significant positive effect of stump harvesting on the height growth of the trees was revealed, compared to control plots with no ground preparation. In one study site stump harvesting was revealed to have a positive effect on the morphologic parameters of twigs and needles, while no differences were noted in the other two sites. The nutrient content of the needles was similar between the treatments across all study sites. Stump harvesting had no effect on the spread of Heterobasidion sp. and Armillaria sp. in the new forest generation. Root infections in young trees with Heterobasidion sp. were detected as early as within two growing seasons from planting. The infection was most severe in the Hepatica site type stand, where 90% of the trees in the previous forest generation had been infected by Heterobasidion sp. In the two other stands studied, where the share of infected trees in the previous generation had been 26% and 16%, Heterobasidion sp. was significantly less widespread. The main causal agent of root rot on all the sampling sites was H. parviporum, but the presence of Armillaria sp. was also remarkable.
Entoleuca mammata
causing Hypoxylon canker (HC) is one of the most serious pathogens that are colonising
Populus
species. The area of fast-growing hybrid aspen plantations has remarkably increased in ...northern Europe because of the high demand for woody biomass, but the prevalence of HC and the stand-related and environmental factors that favour its presence have rarely been monitored in such monocultural plantations. The presence of
E. mammata
in Estonia was proven by ITS sequence on hybrid aspen. Repeated monitoring after 4 years in 24 hybrid aspen plantations found that the share of visually damaged trees by HC increased from 0.6% (15-year-old trees) to 1.6% (19-year-old trees). The mortality rate of the infected trees during the 4 years was 100%. The probability of HC incidence was favoured by tree vigour and higher soil acidity. The higher susceptibility of more vigorous trees might be related to their trade-off between productivity and defence compounds. The share of trees with clear visual symptoms of HC can be considered marginal, but the aggressive nature of the pathogen suggests the need to extend the monitoring period, especially in recently thinned sites, and to expand the observations to native
Populus tremula
stands.
Chaga mushroom (Inonotus obliquus) is a pathogenic fungus that grows mostly on birch species (Betula pendula Roth and B. pubescens Ehrh.) and has traditionally been used as an anticancer medicine. ...This study aimed to compare the chemical composition and cytotoxic activity of chagas growing on both Betula spp. on various cancer cell lines. The freeze-dried extracts contained triterpenes inotodiol, lanosterol betulin, and betulinic acid typical to conks growing on Betula species. The cytotoxic activity of chaga growing on Betula pendula and B. pubescens 80% ethanolic extracts against 31 human cancer cell lines was evaluated by a sulforhodamine B assay. Chaga extract showed moderate activity against all cancer cell lines examined; it did not result in high cytotoxicity (IC50 ≤ 20 µg/mL). The strongest inhibitions were observed with chaga (growing on B. pendula) extract on the HepG2 and CAL-62 cell line and with chaga (from B. pubescens) extract on the HepG2 cell line, with IC50 values of 37.71, 43.30, and 49.99 μg/mL, respectively. The chaga extracts from B. pendula exert somewhat stronger effects on most cancer cell lines studied than B. pubescens extracts, which can be attributed to a higher content of inotodiol in B. pendula extracts. This study highlights the potential of chaga as a source of bioactive compounds with selective anticancer properties. To the best of our knowledge, this study is the first investigation of the chemical composition of I. obliquus parasitizing on B. pubescens.
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