Zbigniew Sierota

The long history and widespread occurrence of Robinia pseudoacacia L. in Europe are increasingly associated with numerous fungal species, including pathogens. Based on literature review data from East-Central Europe (Belarus, Lithuania, Poland, western Ukraine, and northern Germany), 137 fungal taxa were identified on this tree species, including 50 Ascomycota and 87 Basidiomycota. Bearing in mind the varied history of mycological research in the analysed countries, the highest number of taxa was recorded in Poland (108), followed by northern Germany (34) and western Ukraine (24), while Belarus (6) and Lithuania (4) provided the fewest records. Saprotrophic fungi dominated (57%), whereas obligate and facultative parasites accounted for 43%. Among the identified fungi, 71 species caused white rot, and three caused brown rot. The most represented genera were Coprinellus, Crepidotus, and Fusarium. The results of the literature review indicate that R. pseudoacacia serves as an important host and substrate for many fungal species. We hypothesise that this may be influenced, among others, by increased trade, changes in land use, climate change (shifts in the distribution of the tree and individual fungi) and the native fungi’s ability to colonise a new host. In the context of further climate change and the increasing importance of this invasive tree in Europe, fungal pathogens may significantly affect the sustainability of its stands. The greatest threats include root pathogens of the genus Armillaria, wood-decaying fungi such as Fomitiporia robusta and Laetiporus sulphureus, powdery mildews (Erysiphe spp.), and fungi of the genus Fusarium. On the other hand, R. pseudoacacia may have a positive impact on biodiversity in the environment, providing a habitat or substrate for at least 30 threatened fungal species.

The ecological role of Ischnoderma benzoinum in conifer stands remains poorly understood, particularly with regard to its potential to compete with the root rot pathogen Heterobasidion annosum. This study investigated the growth dynamics, wood decay capacity, and competitive interactions of two I. benzoinum isolates (originating from Pinus sylvestris and Picea abies) with two H. annosum isolates from the same host species, and with the biocontrol fungus Phlebiopsis gigantea. Laboratory assays involved growth on malt extract agar for 14 days, and single and dual inoculations on pine and spruce wood for 60 and 120 days. Both I. benzoinum isolates exhibited growth rates on medium comparable to those of H. annosum. On spruce wood, I. benzoinum caused the greatest mass loss, whereas H. annosum dominated on pine. In most dual cultures, wood mass loss was similar to that in single cultures; however, in the pairing of the spruce-derived I. benzoinum with P. gigantea, decay was significantly reduced, indicating antagonistic interaction. Competitive outcomes in dual cultures varied markedly. The pine-derived I. benzoinum strongly suppressed the pine-derived H. annosum, whereas the spruce-derived H. annosum consistently outcompeted both I. benzoinum isolates. P. gigantea strongly inhibited I. benzoinum mycelial growth and frequently reduced its decay activity. These findings demonstrate that I. benzoinum can function either as a strong competitor or as a co-colonizer with H. annosum, with interaction outcomes determined by isolate origin and host tree species. The capacity of I. benzoinum to match H. annosum in wood decay efficiency, particularly on spruce, suggests that it may influence disease progression and nutrient cycling in coniferous forests. This work advances understanding of fungal community dynamics in wood decomposition and highlights the need for further ecological and molecular studies to clarify the role of I. benzoinum in forest health and management.

A variety of elements in nature, from a pine cone’s bracts to a spiral galaxy, are described by a unique mathematical relationship described by Fibonacci as adhering to the “golden ratio”. In forest management, various models are used to achieve a balance between forest use and conservation that meets societal expectations in both ecological and economic terms. In Central European countries, where forest management has been subordinated to the timber industry, such a transition is still in progress, and people continue to look for an acceptable balance between forest conservation and management. The main objective of this paper is to review approaches to forest management in Central Europe with the aim of contributing to current discussions on forest management models in Europe. We anticipate that the new EU Biodiversity Strategy for 2030 will implement the billion-tree afforestation program with appropriate consideration of forest potential based on the tenets of sustainable management and that the future climate will be neutral. We hope that the forestry aspects of the strategy will provide a positive impetus to forest management by finding effective compromises between forest conservation and forest use in furthering the aims of sustainable development.

In many spruce stands, trees are frequently attacked by the pathogen Heterobasidion parviporum, albeit without visible symptoms in the crown. In the present work, the results of the presence of stem rot, assessed by PICUS Sonic Tomography, and the fungal biota on trees and stumps in eight plots in the Puszcza Borecka Forest are described. The plots were located in stands on original forest soil (4) and on post-agricultural soil (4), where around a stump with H. parviporum symptoms (signs of internal rot and basidiocarps), 30 trees were selected and examined for internal rot. Wood samples were collected from two selected trees for fungal molecular analysis. A total of 79 fungal taxa were found, including 57 taxa in plots on post-agricultural soil and 45 on forest soil. There were 395 fungal records on stumps and 22 records on trees, therein, from the inner parts of felled trunks. Significant differences in the Chao-1 diversity index indicate that the origin of the soil—post-agricultural or forest soil—influenced the alpha diversity of the fungal communities in the forests studied. The values of the Shannon and Simpson indices show that the two communities were similar in terms of species numbers. The presence of basidiomata of H. parviporum and two species of Armillaria (mainly A. cepistipes) in samples on all plots is striking, although Armillaria spp. was detected more frequently. Most of the species identified were typical saprotrophs, although rare species were also found, such as Entoloma byssisedum, Onnia tomentosa, Physisporinus vitreus, Postia ptychogaster, and Ramaria apiculata. The presence of H. parviporum in the inner woody parts was confirmed by PCR analysis, and decay was detected even up to a stem height of 6 m. Armillaria was the dominant genus in the studied stands and plays a significant and underestimated role in heartwood decay of old spruce trees in Puszcza Borecka Forest.

The mycobiota of the fine roots of Pseudotsuga menziesii were studied as a measure of the adaptation of this alien species to new soil and climatic conditions. We hypothesized that after approximately 130 years of growth in a given habitat, the fungal community colonizing the fine roots of introduced trees would resemble the biota of Pinus sylvestris and Fagus sylvatica in surrounding stands of similar age and site conditions. The genetic material isolated from the fine roots was subjected to metagenomic analysis. We recorded 33, 97 and 95 OTUs exclusively from root samples of Douglas fir, beech and pine, respectively; 124 were common to all sample types. The biota from the roots of P. menziesii featured a less diverse taxonomic composition and were characterized by the highest proportion of symbiotrophs (71.8%) versus saprothrophs (5.6%) and pathogens (0.24%). Some fungal taxa (19) in the roots of P. menziesii were common with the biota in the roots of other adjacent trees, while some (7) were unique to Douglas fir. Our results indicate a locally differentiated strategy of naturalness of fungi inhabiting soil and roots of P. menziesii, although 130 years have passed since the introduction of the species.

Drought in the forest is not only a prolonged state of water shortage, but also an occasion where interactions between plants and fungi are affected. Water efficiency accelerates a range of pathologies in interactions between organisms, influencing the ecosystems and their interacting biological components. This study focuses on the role of mycorrhizal and endophyte fungi in alleviating the effects of soil water shortage, and on the impact of their altered activity during drought on the health of trees. The issues presented here show the fundamental role of the mycorrhizal mycelium and the mechanism of water transport to the plant in the course of other phenomena (withering, pathogenesis, endophytes biology) that occur in trees under influence of drought, with particular attention on managed coniferous stands. Conclusions resulting from published information on this topic emphasize the negative impact of soil moisture deficiency on the ectomycorrhizal fungi functioning and, in contrast, on the promotion of the growth of some endophytes, pathogens and hemi-parasitic mistletoes (Viscumspp.).

In fall 2018 and 2019, we assessed colonization by fungi on Douglas fir trees [Pseudotsuga menziesii (Mirb.) Franco], white pine (Pinus strobus L.), and red cedar (Thuja plicata D. Don.) on selected experimental plots of the former Prussian Experimental Station, where nonnative tree species were introduced from North America over a century ago. The presence of sporocarps on trunks, root collars, and stumps as well as the litter layer in the soil within a radius of 0.5 m around the trunk of the tree was determined. Additionally, the volume of dead wood on the forest floor of the entire plot was assessed. We recorded numerous fungi on trees and stumps as well as in the litter and soil. For the 31 plots in 12 forest districts, we determined 745 sporocarps of 48 taxa, with 335/19 on the wood of P. menziesii trees and stumps, 377/15 on P. strobus, and 33/6 on T. plicata trees. The highest share of trees with various trunk damage levels was found for T. plicata (70.3%) and the lowest for P. menziesii (6.2%). Among the root parasitic fungi, Heterobasidion sp. and Armillaria sp. were found, especially on the collars and stumps of T. plicata and P. strobus; we did not find basidiomata of both pathogens on P. menziesii. The volume of dead wood within the P. menziesii plots averaged 7.1 m3/ha, whereas in T. plicata plots, it was 56.3 m3/ha. We identified 10 taxa that have not been reported in association with P. strobus for Poland (Cylindrobasidium laeve, Dacrymyces sp., Exidia pithya, E. saccharina, Gymnopilus pnetrans, Leptoporus mollis, Mycena sanguinolenta, Tapinella panuoides, Trametes versicolor, and Xylaria hypoxylon) and three taxa (Exidia pithya, Leptoporus mollis, Serpula himantioides) associated with T. plicata.

In Central Europe, deforestation led to a reduction of forest area by almost 80%, compared to the original area, by the beginning of the 20th century. At this point in time, a period of intensive reforestation began in an effort to restore forest areas. This process of reforestation, especially on post-agricultural land, continues to this day. This article examines reforestation and natural regeneration on former farmland and the factors that influence the current state as well as the future growth of the forest. Ancient and contemporary views on the functioning of stands on post-agricultural land created by both, natural and forced succession (i.e. afforestation), are recalled. In Poland, this issue primarily concerns managed state forests, which cover an area of over 2 million hectares. We discuss the differences in the development of these stands resulting from the history of agricultural cultivation, the type of afforestation, the influence of environmental factors as well as biotic threats to their development. Furthermore, the need to change the silviculture-, protection- and endowment-based approach to forest management in stands on post-agricultural land is highlighted.

Norway spruce trees weakened by soil drought and progressive die-off of mycorrhizas in root systems become susceptible to infection by rhizomorphs of Armillaria spp. The developing mycelium of this necrotroph induces resin channels in wood, and the induced resin releases some volatile compounds which falsely signal bark beetles that it is safe to invade the host. As a result of the developing beetle outbreak, host trees die, becoming a long-term stock of substrate for the fungus in its saprotrophic stage. This hypothesis is discussed as a fungal survival strategy.

This study’s aim was to describe the health condition of Scots pine cultures of up to 10 years old using and comparing various field assessment methods. Since forest districts report on the health of stands annually, we assumed that for a proper health analysis it is necessary to develop a simple and yet reliable assessment method that allows for determining the share of fungal pathogen infection in the stand (both foliar and root pathogens) and their differentiation from symptoms of abiotic factors such as drought. Six different methods of health assessment were tested in selected Forest Districts across Poland. We found that the most reliable assessment of the health condition of young stands is obtained with the surface method ‘MF’ (phytopathological monitoring method) and the linear ‘Z’ method, which uses transects of 30 meters in three rows in the shape of the letter Z.