The aim of this research was to evaluate the amount of woody debris (m³/ha) on the forest floor and the associated wood-colonizing fungi. The study was performed in the Taborz region, known for its Scots pine provenance experiments, against the background of a recently launched Polish legislation to protect the biodiversity on the forest floor in managed (harvested) stands. We investigated a managed stand (136-years-old) and the reserve stand ‘Sosna Taborska’ (261-years-old). In the reserve stand, the mean volume of woody debris was six times higher than in the managed forests, i.e. 65 versus 11 m³/ha. In addition, in the reserve stand, the number of fungi taxa colonizing the dead wood was larger than in the managed stands, with a higher number of fruitbodies. Total fungal richness was higher in the reserve than in the managed stand, i.e. 28 versus 12 species. The dominant taxa at both sites were Fomitopsis pinicola and Fomes fomentarius, although some taxa were only found in the reserve (e.g., Stereum hirsutum). The volume of woody debris as well as the diversity of fungi in the managed stand were lower than in the reserve, albeit greater than in other Scots pine stands in Poland. These results testify to the gains in biodiversity yielded by the management conservation management approach at the reserve stand.

The aim of the study was to evaluate the impact of European beaver (Castor fiber L.) on vegetation diversity and the expansion of non-native plant species in areas surrounding watercourses in Polesie National Park, Poland. The investigation was carried out within six watercourses inhabited by beavers and four comparison watercourses where beaver were absent. European beaver living in the park had a small excursion range, reaching a maximum distance of 25 m from the watercourse so that effects on vegetation diversity were limited to the immediate vicinity of the watercourse. Beaver significantly influenced diversity of the tall tree and forest floor vegetation, while it did not significantly modify the diversity of the low tree and shrub layer. Five alien plant species were documented. The alien species most strongly associated with beaver activity was devil’s beggartick (Bidens frondosa L.), which occurred in the immediate vicinity of beaver dams. Other alien species most benefiting from the presence of beaver were giant goldenrod (Solidago gigantea Aiton) and black cherry (Prunus serotina Ehrh.). Our study confirmed hypotheses found in literature according to which beaver activities that reduce the proportion of native species can promote the expansion of plant alien species.

The impact of the European beaver Castor fiber on deadwood resources near dams on the rivers of Wigry National Park (northeastern Poland) has been analyzed. The river sampling area was subdivided into the flooded zone, scarp and upland. We found that beaver feeding was limited to the flooded zone and the scarp. Within a distance of 40 m of the river, beavers browsed 75% of all deadwood pieces (wood debris, stumps, dead trees). The wood generated via direct browsing by beavers made up 5% (3.29 m3/ha) of the total wood volume and 35% (641 pieces/ha) of the total number of wood pieces in this region. The beavers mostly left small pieces of wood (with a mean diameter of about 4 cm) at an area after feeding. The deadwood volume and number of pieces were significantly different in front and behind the dam only in the flooded zone. The volume of deadwood in front of the dam in the flooded zone was higher by 65% than behind the dam (102 and 62 m3/ha, respectively), and the number of pieces was higher by ...

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.

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.

The aim of the study was to determine the influence of the period of occurrence of the European beaver (Castor fiber L.) population on foraging strategies and on the diversity of the species of cutting trees and shrubs. Two beaver populations at different stages of development - a younger (42yr) population from the Kampinos National Park and an older (72yr) population from the Wigry National Park were studied. Both populations foraged according to the Optimal Foraging Theory (OFT), according to which the distance to available food depends on its size and the distance to reach it. The dominant factors modifying the foraging behavior of beavers and their foraging ranges were the presence of a dam, the availability of preferred species. The greater diversity in the areas where beaver are found may be the result of both beaver activity and the selection of more attractive areas for dam construction.