Radosław Gawryś

This study presents new data on the occurrence of protected, endangered and locally rare bryophyte species in the Nizina Północnopodlaska lowland (northeastern Poland). This area includes some of the most valuable natural complexes in Poland, such as the Białowieża Forest, the Knyszyń Forest, and the Kotlina Biebrzańska basin. Between 2009 and 2026, 481 bryophyte localities were recorded, comprising 82 moss and 18 liverwort species. In total, 39 taxa are legally protected in Poland, including 17 under strict protection, and nine moss species are nationally threatened, among them the critically endangered Antitrichia curtipendula, Paludella squarrosa and Pseudocalliergon trifarium. Buxbaumia viridis, Dicranum viride, and Hamatocaulis vernicosus are also listed in Annex II of the EU Habitats Directive. Eight species are reported from the region for the first time: Bryum rubens, B. violaceum, Campylopus introflexus, C. pyriformis, Frullania tamarisci, Philonotis caespitosa, Rhynchostegium murale and Ulota intermedia. Most of the protected and threatened taxa are associated with peatlands and near-natural forest complexes. Their conservation requires the maintenance of a stable forest microclimate and, in open wetlands, active management aimed at preventing succession. The results indicate that knowledge of the regional bryoflora remains incomplete and emphasize the need for further studies, particularly in the western and urbanized parts of the lowland.

Ponds created by beavers represent unique aquatic ecosystems that influence hydrological, chemical and biological conditions, including the microbiology of the water. The activity of these animals promotes biodiversity and water purification processes, but can also lead to the accumulation of pollutants. Water retention in beaver ponds promotes the development of bacteria and other microorganisms that play an important role in biogeochemical cycles. Long‐term water stagnation can lead to anaerobic conditions and the formation of toxic compounds, which in turn can limit the diversity of benthic organisms. Beavers play a key role in shaping these habitats, and microbiological studies of their reservoirs provide a better understanding of their impact on aquatic ecosystems, self‐purification processes and potential biological threats. Metagenomic analysis revealed the presence of 365 bacterial species in water and sediment samples, belonging to 174 genera and 83 families. 83 operational taxonomic units (OTUs) were identified, 62 of which were present in both water and sediments. Although the overall OTU composition was similar in both environments, greater variability was observed in the sediments. The statistical differences in OTU distribution between water and sediments were confirmed using the Wilcoxon test.

Impatiens parviflora DC. occurs in various plant communities. Its occurrence has been confirmed in Poland across 13 natural habitats protected under the Habitats Directive. The aim of our work is to determine the differences between the plots with and without I. parviflora in terms of the species richness and ecological conditions of the 9180* habitat-type forest. Using data from 315 plots on which a phytosociological relevés was carried out, we analyzed the geographical variability, the Shannon-Winner index and the indicator species for old forests. Flora diversity was represented using the DCA, and the IndVal index was calculated to determine the species that best characterize the differentiated groups. The highest percentage of monitoring plots with I. parviflora is located in the Sudetes Mountains (67.7%) and the lowest in the Bieszczady Mountains (7.5%). Plots with I. parviflora were characterized by significantly lower tree cover, a higher number of tree species in the stand, a lower height of both the understory and herb layer and a lower number of old forest species. Impatiens parviflora does not affect the total number of species in the understorey but is associated with a lower proportion of species typical of old forests. The presence of I. parviflora also correlates with a higher proportion of young trees in the understorey, suggesting a link with successional processes and habitat disturbance. The spread of I. parviflora is limited by shade-loving trees such as Abies alba Mill. and Fagus sylvatica L. The diversity of the distribution of I. parviflora depends on local conditions, so conservation efforts should take into account the local ecological context.

Antipredator responses of prey are important because of their potential trophic cascade effects. Predator responses are especially important for species that impact the economy, such as ungulates. Past research has focused on the behavioral adaptation of roe deer, the most common ungulate in Europe, to human and lynx pressure. However, the European wolf population has increased in the last decade and in some recently recolonized parts of Poland roe deer constitute the largest food source for wolves. Unlike in moose and red deer, no evidence has yet been found for changes in the vigilance-foraging time ratio in roe deer in response to wolves. We took the unique opportunity to study the behavior of roe deer during the partial recolonization by wolves of a large forest complex (Tuchola Forest) in Poland. Using video cameras, we found that roe deer react differently to the presence of wolves compared with humans. Wolf predation increases roe deer movement. In comparison, anthropopressure causes roe deer to mainly use an avoidance strategy, limiting their activity to times of day when people are not present. This temporal avoidance strategy was similar whether human pressure resulted from recreation or hunting.

Plant communities are being exposed to changing environmental conditions all around the globe, leading to alterations in plant diversity, community composition, and ecosystem functioning. For herbaceous understorey communities in temperate forests, responses to global change are postulated to be complex, due to the presence of a tree layer that modulates understorey responses to external pressures such as climate change and changes in atmospheric nitrogen deposition rates. Multiple investigative approaches have been put forward as tools to detect, quantify and predict understorey responses to these global‐change drivers, including, among others, distributed resurvey studies and manipulative experiments. These investigative approaches are generally designed and reported upon in isolation, while integration across investigative approaches is rarely considered. In this study, we integrate three investigative approaches (two complementary resurvey approaches and one experimental approach) to investigate how climate warming and changes in nitrogen deposition affect the functional composition of the understorey and how functional responses in the understorey are modulated by canopy disturbance, that is, changes in overstorey canopy openness over time. Our resurvey data reveal that most changes in understorey functional characteristics represent responses to changes in canopy openness with shifts in macroclimate temperature and aerial nitrogen deposition playing secondary roles. Contrary to expectations, we found little evidence that these drivers interact. In addition, experimental findings deviated from the observational findings, suggesting that the forces driving understorey change at the regional scale differ from those driving change at the forest floor (i.e., the experimental treatments). Our study demonstrates that different approaches need to be integrated to acquire a full picture of how understorey communities respond to global change.

As a result of species protection in Poland, wolves now appear in places that are attractive for human recreation, increasing their exposure to dogs. This creates a risk of spontaneous direct interactions between these two canine species. Aggressive interactions between the gray wolf and the domestic dog lead to human–large predator conflicts. This study examined wolf–dog interactions using data collected in an online questionnaire and included questions related to factors that might influence the likelihood of interactions between these canines. One of the most important factors affecting the likelihood of interaction between a dog and a wolf was the distance between the dog and the human. The number of wolves was also important—the more wolves, the more likely they were to interact with dogs. The risk of interaction also significantly increases with decreasing distance to human settlements. There were also statistical differences in terms of the type of outdoor activity being engaged in. Hunting was seven times more likely to result in a wolf–dog interaction than normal walk. We postulate that the choices made by the human (dog control and type of recreation) caring for the dog are an important factor that can reduce the risk of direct contact between dogs and wolves.

Hurricane winds are one of the most important abiotic factors in shaping the structure of the forest and the processes that occur in it. The aim of research was to determine regeneration processes and changes in the structure of forest stands caused by the windstorm in 1983. The research, based on stand tables from the years 1982, 1984, 1989 and 2014, was carried out on nine permanent research plots in the Białowieża Forest. The mean number of trees (MNT) taller than 1.30 m decreased by 13.7% after the windstorm. In 2014, MNT increased compared to 1984 (142%) and 1989 (53%). A significant decrease in the share of Picea abies (L.) H. Karst., thicker than 7 cm DBH and a significant increase in the share of Carpinus betulus L. was observed. Species richness for trees thicker than 7 cm DBH indicated a significantly lower species richness in 1982 and 1984 (12 species) compared to 1989 (14) and 2014 (16). The windstorm did not have a direct effect on the species richness, species composition of stands or the distinguished tree layers, except for trees thicker than 55 cm DBH. The observed changes in tree density in the lower layers of the stand prove that the regeneration process does not start immediately and continues even 30 years after the windstorm. Intermediate-severity windthrow accelerated natural changes in the stand structure.