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In forest nurseries seedlings are commonly produced using different cultivation systems which may have a profound effect on the extent of root colonisation by ectomycorrhizal (ECM) fungi and, consequently, on subsequent performance of the outplanted seedlings under field conditions. In this study, we compare effects of bare-root and containerised cultivation systems on mycorrhization, establishment and growth of nursery-produced Picea abies. One hectare experimental plantation was established on poor fertility sandy site. In total, 1250 seedlings of each treatment were planted in rows as ten individual replicates. The results of this study showed that production of P. abies seedlings using containerised system can yield abundant ECM colonisation of seedling roots and significantly improve seedling survival in the field. Some reduction in height increment may occur during the first years as a possible cost for support of ECMs. Study demonstrated that selection of proper cultivation system might result in similar or higher mycorrhization and survival rates of outplanted seedlings than achieved by expensive and laborious artificial mycorrhization.

Forest fires represent a significant ecological disturbance in ecosystems that increasingly affects Pinus heldreichii H. Christ forests at the upper tree line in Montenegro, due to climate change and anthropogenic factors. Soil samples were collected from five high-altitude sites in the Kuči Mountains, including three post-fire sites (2-, 4-, and 6-years post-fire) and two unburned control sites. High-throughput sequencing and soil chemical analyses were conducted to assess fungal diversity, community composition, and soil nutrient properties. The results showed that fungal diversity was significantly higher in unburned soils compared to post-fire soils, with the most prominent changes in ectomycorrhizal fungi, which are crucial for pine regeneration. The fungal community composition differed markedly between the post-fire and unburned sites, with specific taxa such as Hygrocybe conica (Schaeff.) P. Kumm. and Solicoccozyma aeria (Saito) Yurkov dominating the post-fire environments. Despite this, the fungal richness did not significantly change over time (2-, 4-, or 6-years post-fire), suggesting the slow recovery of fungal communities in high-altitude environments. In addition to shifts in fungal biodiversity, the post-fire soils exhibited higher levels of available phosphorus, likely due to the conversion of organic phosphorus into soluble forms during combustion. However, the organic matter content remained unchanged. This study provided important insights into the long-term ecological impacts of forest fires on high-altitude P. heldreichii forests and underlined the importance of preserving unburned forest areas to maintain fungal biodiversity and support natural regeneration, as well as the potential need for active restoration strategies in fire-affected regions. [ABSTRACT FROM AUTHOR]

In Europe, Pinus sylvestris and Picea abies are the most common coniferous tree species used in commercial forestry, which rely on high‐quality reproductive material for successful reforestation. Clear‐cut harvested forest sites are often replanted using tree seedlings, which are produced in forest nurseries using seeds from seed orchards. However, incidences of fungal diseases in seedling production show that a better knowledge of seedborne fungi, including fungal pathogens, is needed to manage diseases in forest nurseries. This study aimed to assess seedborne fungal communities associated with commercial seeds of P. abies, P. sylvestris and Larix sp. seeds originated from geographically separated regions in Sweden, Belarus, Finland and Poland. Fungal communities were obtained first from the seed surface and then from the seed tissue. These were analysed using high‐throughput sequencing of the ITS2 rDNA region. The results showed that fungal diversity and community composition differed between the seed surface and the seed tissue. Picea abies accommodated a higher fungal diversity than P. sylvestris. In addition, a strong host affinity of the fungal community composition on the seed surface and a weaker association in the seed tissue was found. Fungal communities on P. abies and P. sylvestris seed surface differed significantly between geographical regions, whereas no regional differences were found in the seed tissue. The seedborne fungal communities included a high proportion of plant pathogens, among which the most abundant were Sydowia polyspora (13.3%), Phoma herbarum (11.2%) and Sirococcus conigenus (3.8%). In conclusion, the results showed (a) characteristic fungal diversity and community composition between the seed surface and the seed tissue; (b) a host‐specific fungal community composition on the seed surface and in the seed tissue; (c) regional difference in fungal communities on P. abies and P. sylvestris seed surface, thus the movement of seeds between different regions can contribute to the spread of fungal diseases; and (d) the presence of a high incidence of seedborne fungal pathogens which suggest a potential need of preventative or control measures to reduce the occurrence of these fungi on the seed surface. [ABSTRACT FROM AUTHOR]

Simple Summary: Here we investigated fungal communities associated with three species of siricid wood wasps occurring in Lithuania. Siricid wood wasps are pests of weakened forest trees or develop on the stem of dead trees, which may also vector tree-pathogenic fungi. The results demonstrated that, generally, species–specific fungal communities are associated with each species of wood wasps, and that the economically important tree pathogen Amylostereum chailletii was among the most common fungal taxon associated. The study, therefore, provided new insights into the ecology and symbiotic associations of these wood wasps. We investigated the diversity and occurrence of wood wasps in Lithuania and determined communities of associated fungi. Trapping of wood wasps resulted in three different species, including Sirex juvencus, Urocerus gigas, and Tremex fuscicornis. Fungal culturing from adult females of T. fuscicornis mainly resulted in fungi from the genera Penicillium and Trichoderma. High-throughput sequencing of ITS2 rDNA resulted in 59,797 high-quality fungal sequences, representing 127 fungal OTUs. There were 93 fungal OTUs detected in U. gigas, 66 in S. juvencus, and 10 in T. fuscicornis. The most common fungi were Fusarium sporotrichioides (63.1% of all fungal sequences), Amylostereum chailletii (14.9%), Penicillium crustosum (7.8%), Microascus sp. 2261_4 (5.0%), and Pithoascus ater (2.1%). Among these, only A. chailletii was found in all three insect species with the highest relative abundance in U. gigas (15.2%), followed by S. juvencus (7.7%), and the lowest in T. fuscicornis (0.3%) (p < 0.0003). Correspondence analysis of fungal communities showed a distant placement of different species of wood wasps, indicating that fungal communities in each of these were largely different. In conclusion, the study showed that the economically important tree pathogen A. chailletii was among the most common fungal OTUs associated with siricid wood wasps. [ABSTRACT FROM AUTHOR]

In forest nurseries, foliar fungi play a key role in the health of tree seedlings. The aimof this study was to study the diversity and the development of foliar fungal species associated with nursery-grown Pinus sylvestris, and to evaluate the effect of two biological control products and two growth-stimulating products on seedling growth and disease control, as well as seedling associated fungal community. The study was conducted at four Swedish forest nurseries. Fungal communities were assessed from non-symptomatic needles using high-throughput sequencing of the ITS2 rRNA region. The fungal pathogens Cladosporium sp. (15.1%), Phoma herbarum (14.5%), and Alternaria alternata (5.5%) were among the most abundant fungi. Results showed that the nurseries and the development of fungal communities influenced the occurrence of dominant fungal taxa. Disease prevalence was low and microbial treatments had no significant impact on seedling growth and survival, nor on the number of fungal operational taxonomic units (OTUs), species diversity, and species evenness (p > 0.05). In conclusion, the results showed a dynamic change in foliar fungal community structure over the growing season. With appropriate nursery management strategies and under suitable climatic conditions, nursery seedlings can remain healthy even in the presence of fungal pathogens. [ABSTRACT FROM AUTHOR]