Patterns of avian tree usage in the primeval temperate forests of Bialowieza National Park.

Species distribution and resource utilization are a fundamental aspect of ecology. By analyzing the tree space usage by birds and determining the species composition of birds across different parts of trees, our study could shed light on the mechanisms shaping co-occurrence patterns in bird communities. Therefore, our study aimed to determine the species composition of birds across different parts of trees. We investigated whether species richness differs between positions on a tree and how these positions influence the probability of occurrence of the 10 most frequently observed bird species. To achieve this, we observed birds within permanent plots in Bialowieza National Park (BNP) and analyzed the distribution patterns of birds within six vertical and three horizontal sectors of trees. The compositional dissimilarity between tree sectors was assessed using detrended correspondence analysis. We employed generalized linear mixed-effects models to examine differences in species richness. The majority of the BNP bird community was associated with the branches, while other birds occupied the tree crown trunks and the understory trunks. Species richness was the highest on branches in the crown part of trees, followed by lower species richness on trunks associated with crowns, and the lowest richness was observed on branches and trunks in the understory. These results indicate that branches in the middle and lower parts of the crown serve as avian diversity hotspots on trees, likely due to the abundance of various food sources. The differing patterns of tree usage by specific bird species may suggest the avoidance of interspecific competition for resources. The study results of tree usage by bird species obtained in the primeval forest provides a reference point for studies conducted in human-altered woods.

Verified hypotheses on the "nurse" and "burial" effects on introduced Quercus rubra regeneration in a mesic Scots pine forest.

A previous study on the encroachment of North American northern red oak Quercus rubra L. into the mesic Scots pine forest (in central Poland) revealed high abundances of seedlings and saplings under shrubs, with lower abundances in open areas or clumps of bilberry Vaccinium myrtillus L. It was unclear whether the regeneration success of Q. rubra is enhanced by the presence of shrubs due to their "nurse effect", and how burying acorns of different sizes in soil or moss affects the survival of oak seeds and seedlings (a "burial effect"). Results of a previous observational study were verified in an experimental study: a pool of 900 large-, medium-, and small-sized acorns was sown under moss cover in open areas and within bilberry clumps and in soil under shrubs in 2018 and monitored for 3 years in natural conditions. The majority of sown acorns were lost, mainly due to acorn pilferage, lack of germination and the death of sprouting acorns. However, acorn and seedling survival depended significantly on acorn size and differed among the microsites studied. Viable seedlings were twice as likely to develop from large- and medium-sized as from small-sized acorns, and they grew mainly from acorns sown under moss cover, confirming a positive "burial effect." Seedling survival was three times higher in bilberry and open areas, than under shrubs; however, seedlings "nursed" by shrubs were less threatened by large ungulates. Only a small part of the pool of sown acorns contributes to the reproductive success of Q. rubra in the mesic Scots pine forest. Microsites characteristic to this type of forest are suitable for northern red oak regeneration; however, bilberry favors acorn survival and germination and early seedling growth, moss cover favors acorn survival and germination, while shrubs protect surviving seedlings from herbivory.

Forest herb species with similar European geographic ranges may respond differently to climate change.

Many phenological studies have shown that spring geophytes are very sensitive to climate change, responding by shifting flowering and fruiting dates. However, there is a gap in knowledge about climatic drivers of their distributions and range shifts under climate change. Here we aimed to estimate climate niche shifts for four widely distributed and common geophytes of the nemoral zone of Europe (Anemone nemorosa, Anemone ranunculoides, Convallaria majalis and Maianthemum bifolium) and to assess the threat level under various climate change scenarios. Using MaxEnt species distribution models and future climate change scenarios we found that the precipitation of the warmest quarter was the most important factor shaping their ranges. All species studied will experience more loss in the 2061-2080 period than in 2041-2060, and under more pessimistic scenarios. M. bifolium will experience the highest loss, followed by A. nemorosa, A. ranunculoides, and the smallest for C. majalis. A. ranunculoides will gain the most, while M. bifolium will have the smallest potential range expansion. Studied species may respond differently to climate change despite similar current distributions and climatic variables affecting their potential distribution. Even slight differences in climatic niches could reduce the overlap of future ranges compared to present. We expect that due to high dependence on the warmest quarter precipitation, summer droughts in the future may be particularly severe for species that prefer moist soils. The lack of adaptation to long-distance migration and limited availability of appropriate soils may limit their migration and lead to a decline in biodiversity and changes in European forests.

How do urbanization and alien species affect the plant taxonomic, functional, and phylogenetic diversity in different types of urban green areas?

Human pressure on urban landscapes has serious consequences for urban plant species. Therefore, environmental and anthropogenic factors affect the assembly of urban wildlife in plant communities. For biodiversity conservation and ecosystem services in urban areas, it is crucial to understand the impacts of urbanization as well as the introduction of alien plant species on urban plant communities. On 47 sites in Poznan (W Poland), we studied variation within and between three management greenery habitats, i.e., urban parks, greenery associated with housing estates, and urban grasslands, as they relate to taxonomical, functional, and phylogenetic alpha and beta diversity. We also examined how urbanization (measured by ISA) and alien plant species relate to vegetation compositional differences. We found that both urbanization and alien plant species cover decreased alpha diversity, while urbanization had various impacts on beta diversity within each studied habitat. Our results suggest that human pressure leads to similarities in the urban flora, where plant species with specific functional traits adapted to the urban environment. To achieve sustainable urbanization, urban planners should not only create diverse green spaces but also eliminate alien plants, increasing the role of urban land management in promoting the wildness of plant biodiversity in cities.

Temperate forest understory vegetation shifts after 40 years of conservation.

Understanding how vegetation composition and diversity respond to global changes is crucial for effective ecosystem management and conservation. This study evaluated shifts in understory vegetation after 40 years of conservation within Drawa National Park (NW Poland), to check which plant communities changed the most, and whether vegetation shifts reflect global change symptoms (climate change and pollution) or natural forest dynamics. Using ordination and generalized mixed-effects linear models, we assessed changes in alpha diversity metrics, accounting for taxonomic, functional, and phylogenetic aspects within 170 quasi-permanent plots, surveyed in 1973-85 and resurveyed in 2015-19. We found an overall homogenization of forest vegetation and specific shift patterns in certain forest associations. In coniferous and nutrient-poor broadleaved forests, the overall number of species increased due to the replacement of functionally distinct or specialized species with more ubiquitous species that could exploit increased resource availability. In riparian forests and alder carrs we found either shifts from riparian forest to alder carrs or to mesic broadleaved forests. The most stable communities were fertile broadleaved forests. Our study quantified shifts in taxonomic, functional, and phylogenetic diversity after 40 years of conservation and provides important insights into the shifts in vegetation composition in temperate forest communities. In coniferous and nutrient-poor broadleaved forests we found an increase in species richness and replacement of functionally distinct or specialized species by ubiquitous species, indicating increased resource availability. Shifts between wet broadleaved forests and transition into mesic forests suggest water limitation, which can be related to climate change. The most stable were fertile broadleaved forests fluctuating due to natural stand dynamics. The findings highlight the need for ongoing monitoring and management of ecological systems to preserve their diversity and functionality in the face of global changes.

Climate change will cause climatic niche contraction of Vaccinium myrtillus L. and V. vitis-idaea L. in Europe.

We estimated climate niche shifts and threat levels under various climate change scenarios for Vaccinium myrtillus L. and V. vitis-idaea L. We developed the MaxEnt species distribution models, and predicted future climatic optima for climate change scenarios for 2041-2060 and 2061-2080. The precipitation of the warmest quarter was the most important factor shaping the climatic niches of the studied species. We predicted the largest shifts in climate niches from the present to the 2040-2060 period, with the most pessimistic scenario predicting significant range losses for both species, mainly in Western Europe. Under the most optimistic SSP126 scenario, both species will lose 39 % of their climatic niche for both periods. In the worst-case scenario (SSP585) for 2061-2080, climatic niche contraction will cover 47 % and 39 % of the current climatic niche for V. myrtillus and V. vitis-idaea, respectively. The predicted changes in species distribution could have far-reaching consequences for temperate and boreal forests due to their crucial biocenotic role in forest ecosystems, high potential for carbon sequestration, and prevention of soil erosion. Furthermore, the changes would likely affect the economic potential regarding fruit production and culturally relevant uses of different parts of the plants, mainly fruits.

Predicted range shifts of invasive giant hogweed (Heracleum mantegazzianum) in Europe.

Heracleum mantegazzianum Sommier & Levier (Giant hogweed) has spread across Europe after its introduction as an ornamental from the native range in the Western Greater Caucasus. In addition to its invasive capability, H. mantegazzianum reduces the alpha diversity of native species in the non-native range and can cause second-degree burns when its phytotoxic sap contacts the skin upon exposure to sunlight. Previous studies on H. mantegazzianum distribution focused on individual countries, therefore we know little about the potential shift of the species distribution under changing climate at the continental scale. To fill that gap in the current knowledge, we aimed to (i) identify the most important climatic factors for the distribution of H. mantegazzianum in Europe, (ii) recognize areas that will be suitable and unsuitable for future climate scenarios to prioritize management action. Our study showed that the mean temperature of the coldest quarter (bio11) and temperature annual range (bio7) were the most important bioclimatic variables predicting the suitable habitat of the species in Europe. For all scenarios, we found that the majority of the range changes expected by 2100 will occur as early as 2041. We predicted an overall decrease in climatically suitable area for H. mantegazzianum under climate change with over three quarters (i.e. 94%) of the suitable area reduced under the Shared Socioeconomic Pathway (SSP) 585 in 2100. However, under the same scenario, climate conditions will likely favour the expansion (i.e. 20%) of H. mantegazzianum in northern Europe. The results from the present study will help in developing a climate change-integrated management strategy, most especially in northern Europe where range expansion is predicted.

Fivefold higher abundance of ticks (Acari: Ixodida) on the European roe deer (Capreolus capreolus L.) forest than field ecotypes.

The European roe deer (Capreolus capreolus) is the most common deer species in Europe. The species can be a reservoir of some tick-borne diseases but it is primarily recognized for its contribution as an amplifier host. In Central Europe, two roe deer ecotypes are living in adjacent areas: field and forest. We investigated differences in tick load and species composition on these two ecotypes. We collected ticks from 160 (80 the forest ecotype and 80 the field ecotype) roe deer culled in Wielkopolska Region (West-Central Poland). The most common was Ixodes ricinus (n = 1610; 99%) followed by Ixodes hexagonus (n = 22; 1%). The dominant life stage of the ticks was female. Prevalence was higher for forest roe deer. Mean number of ticks found on the forest ecotype was almost fivefold higher than on the field ecotype (3.75 ± 0.83 vs. 0.77 ± 0.20 ticks). The mean probability of tick occurrence was threefold higher in the forest (0.915 ± 0.050) than the field ecotype (0.279 ± 0.125). The most infested body parts of roe deer from both ecotypes were the neck and the head.

Black locust (Robinia pseudoacacia L.) range contraction and expansion in Europe under changing climate.

Robinia pseudoacacia is one of the most frequent non-native species in Europe. It is a fast-growing tree of high economic and cultural importance. On the other hand, it is an invasive species, causing changes in soil chemistry and light regime, and consequently altering the plant communities. Previously published models developed for the potential distribution of R. pseudoacacia concerned 2070, and were based mainly on data from Western and Central Europe; here we extended these findings and included additional data from Eastern Europe. To fill the gap in current knowledge of R. pseudoacacia distribution and improve the reliability of forecasts, we aimed to (i) determine the extent to which the outcome of range modeling will be affected by complementing R. pseudoacacia occurrence data with sites from Central, Southeastern, and Eastern Europe, (ii) identify and quantify the changes in the availability of climate niches for 2050 and 2070, and discuss their impacts on forest management and nature conservation. We showed that the majority of the range changes expected in 2070 will occur as early as 2050. In comparison to previous studies, we demonstrated a greater eastward shift of potential niches of this species and a greater decline of potential niches in Southern Europe. Consequently, future climatic conditions will likely favor the occurrence of R. pseudoacacia in Central and Northeastern Europe where this species is still absent or relatively rare. There, controlling the spread of R. pseudoacacia will require monitoring sources of invasion in the landscape and reducing the occurrence of this species. The expected effects of climate change will likely be observed 20 years earlier than previously forecasted. Hence we highlighted the urgent need for acceleration of policies aimed at climate change mitigation in Europe. Also, our results showed the need for using more complete distribution data to analyze potential niche models.

Ash dieback, soil and deer browsing influence natural regeneration of European ash (Fraxinus excelsior L.).

European ash (Fraxinus excelsior L.) dieback affects both overstory trees and natural regeneration. The decline of ash caused by severe crown defoliation and branch mortality has a high impact on ash natural regeneration. The site factors affecting the disease symptoms vary significantly and are not fully understood. Hence, we aimed to assess the joined effects of soil fertility and moisture (expressed by soil pH, CaCO3 content, and summer groundwater table level), herbivory, and health conditions connected with Hymenoscyphus fraxineus (T. Kowalski) Baral, Queloz, and Hosoya infestation on natural regeneration of F. excelsior. We examined 32 ash stands in Western Poland across soil fertility gradient. We established randomly selected circular plots (400 m2) in forests with ≥60% of ash in overstory species composition. We assessed natural regeneration density, the proportion of browsed trees, and trees damaged by ash dieback using generalized mixed-effects models. We found a higher proportion of damaged trees in neutral and base soils than in acid soils. Moreover, we found a low proportion of damaged trees in sites with low groundwater table levels. High CaCO3 content decreased the proportion of browsed trees, similarly as high shrub cover. The density of F. excelsior natural regeneration depended on groundwater table level, canopy cover, and proportion of damaged trees. We also found a positive relationship between density and deer browsing. The factor responsible for the higher infestation of saplings (low groundwater table level) also influenced natural regeneration density. This way, our study revealed how soil properties influence ash natural regeneration directly and indirectly. We showed that ash dieback will have a more severe impact on ash regeneration in ash typical sites. This is essential for predicting forest recovery and the ability to resilience after disturbances caused by H. fraxineus. CAPSULE: Joined effects of ash dieback, soil pH, and CaCO3 content, together with soil moisture, as well as deer browsing, affect ash regeneration.

Consequences of different sample drying temperatures for accuracy of biomass inventories in forest ecosystems.

Biomass estimation is one of the crucial tasks of forest ecology. Drying tree material is a crucial stage of preparing biomass estimation tools. However, at this step researchers use different drying temperatures, but we do not know how this influences accuracy of models. We aimed to assess differences in dry biomass between two drying temperatures (75 °C and 105 °C) in tree biomass components and to provide coefficients allowing for recalculation between the given temperatures. We used a set of 1440 samples from bark, branches, foliage and wood of eight European tree species: Abies alba Mill., Alnus glutinosa (L.) Gaertn., Betula pendula Roth., Fagus sylvatica L., Larix decidua Mill., Picea abies (L.) H. Karst., Pinus sylvestris L. and Quercus robur L. The differences between drying temperatures were 1.67%, 1.76%, 2.20% and 0.96% of sample dry masses of bark, branches, foliage and stem wood, respectively. Tree species influenced these differences. Our study provided coefficients allowing for recalculation of masses between the two temperatures, to unify results from different studies. However, the difference in dry mass between the two temperatures studied is lower than the range of uncertainty of biomass models, thus its influence on results of large-scale biomass assessments is low.

Responses of soil mite communities (Acari: Oribatida, Mesostigmata) to elemental composition of mosses and pine needles and long-term air pollution in Scots pine (Pinus sylvestris L.) stands.

Air pollution is an important threat to biodiversity via deposition of high amounts of heavy metals or nutrients (macroelements). In forest ecosystems contamination can be found in plant tissues and the soil environment including soil mesofauna. However, there is little information on how it influences soil mesofauna. Hence, the aim of the study was to evaluate the reaction of soil mites (Acari: Oribatida, Mesostigmata) to long-term air pollution in mature pine (Pinus sylvestris L.) forests in southwestern Poland. The study was conducted in late autumn between October 2008 and 2010 in eight 5000 m2 plots, each within a Scots pine stand. Concentrations of macroelements (C, N, S, Ca, Mg) and heavy metals (Cu, Cr, Cd, Ni, Pb, Zn) were measured in 40 samples of pine needles and 36 bryophyte samples. In total, 360 soil samples were collected for the soil mesofauna analysis. Results of the study include correlations between the sample plot, the year and the soil mite abundance. Among the macroelements analyzed, calcium affected the abundance of mite species the most. Soil mite communities from different forests were dominated by the same species, despite the fact that we found in total 150 mite species, among which there were 106 species of oribatid mites and 44 species of mesostigmatid mites. It seems that, among the elements analyzed, calcium plays the most important, positive role for mite communities. Magnesium had a positive effect on abundance of both mite groups, while nitrogen had a negative effect on diversity of oribatid and mesostigmatid mite communities. Our study indicated that oribatid and mesostigmatid mite communities are stable in areas of long-term contamination, as we did not observe distinct changes in structure and diversity of soil mite assemblages along the pollution gradient.

Response of soil mites (Acari, Mesostigmata) to long-term Norway spruce plantation along a mountain stream.

During the nineteenth and twentieth centuries, coniferous monocultures were introduced, replacing natural broadleaved forests in Central Europe, mainly for economic benefits. In the mountains, Norway spruce [Picea abies (L.) H. Karst] was introduced in large areas previously covered with beech forests and also in natural riverside habitat corridors such as river valleys, despite its negative impact on the soil environment by e.g. organic matter accumulation, decrease of soil pH and changes in C/N ratio. We aimed to check how long-term Norway spruce plantations affect species richness and diversity of soil mites along a mountain river in former mixed and broadleaved forests. The study, based on 342 samples, was carried out in Stolowe Mountains National Park (SW Poland). Understory species biomass, soil pH and soil organic layer thickness significantly affected soil mite communities. Although coniferous forests did not differ from either broadleaved or mixed forests in mite density (number of individuals m-2) and species diversity (H'), they were characterized by low species richness and proportional abundance of Uropodina mites typical for broadleaved forests. In total, 4849 mites classified into 57 species were recorded from all forest types and no unique species were found in the sampled forests. Although the mite communities were dominated by the same common species (Veigaia nemorensis, Paragamasus runcatellus, Leptogamasus obesus and Trachytes aegrota), they still maintain the rare species of broadleaved forests and their high recovery potential may be used in forest conversion.

Natural forest remnants as refugia for bryophyte diversity in a transformed mountain river valley landscape.

Riparian forests are among the most threatened ecosystem types worldwide. Their exploitation and replacement by coniferous plantations affects species pools and contributes to loss of biodiversity. We aimed to investigate bryophyte species pools within different habitat types in a transformed mountain river valley. We especially focused on the contribution of habitat types (relative to their proportional cover) to the species pool of the whole area. The study was conducted along the Czerwona Woda river - a model stream in the Stolowe Mountains National Park (SW Poland, study area: 91.2 ha) - and an example of coniferous plantations replacing natural broadleaved forest vegetation. Our study revealed the presence of 147 bryophyte species. The most valuable habitats in terms of diversity of bryophyte assemblages were remnants of the natural vegetation - broadleaved forests and streams. These habitats, constituting <5% of the study area, hosted ca 40% of the total species pool (61 and 62 species, respectively), while the species pool of Picea abies forests (92 species) was proportional to cover of this habitat type (ca 60%). Remnants of natural vegetation were hotspots of bryophyte diversity within the heavily altered landscape, and may play a future role as sources of recolonization by forest specialists. Our study also confirmed the important role of riparian areas in maintaining bryophyte species diversity at the landscape scale. The river valley studied contributes >20-fold more to the bryophyte species pool of the whole national park than indicated by its size. Thus, river valleys require special treatment - conservation based on natural restoration, and should remain reserved from wood production, as areas providing a wide range of ecosystem services.

Climate change, tourism and historical grazing influence the distribution of Carex lachenalii Schkuhr - A rare arctic-alpine species in the Tatra Mts.

Mountain vegetation is highly specialized to harsh climatic conditions and therefore is sensitive to any change in environment. The rarest and most vulnerable plants occurring in alpine regions are expected to respond rapidly to environmental changes. An example of such a species is Carex lachenalii subsp. lachenalii Schkuhr, which occurs in Poland on only a few isolated sites in the Tatra Mts. The aim of this study was to assess changes in distribution of C. lachenalii in the Tatra Mts over the past 50-150years and the effects of climate change, tourism and historical grazing on the ecological niche of C. lachenalii. We focused on changes in the importance of functional diversity components in shaping plant species composition. Over the past 50-150years, the elevation of the average distribution of C. lachenalii shifted about 178m upward alongside a significant prolongation of the vegetative season by approximately 20days in the last 50-60years. Species composition of plots without C. lachenalii was characterized by competition between plants, whereas on plots with C. lachenalii habitat filtering was the most important component. Our results suggest that climate change was the main factor driving upward shift of C. lachenalii. Moderate trampling enhanced horizontal spread of this plant, whereas cessation of grazing grazing caused decline of C. lachenalii. The three environmental factors studied that determined shifts in distribution of C. lachenalii may also contribute to changes in distribution of other rare mountain plant species causing changes in ecosystem functioning.

How much does climate change threaten European forest tree species distributions?

Although numerous species distribution models have been developed, most were based on insufficient distribution data or used older climate change scenarios. We aimed to quantify changes in projected ranges and threat level by the years 2061-2080, for 12 European forest tree species under three climate change scenarios. We combined tree distribution data from the Global Biodiversity Information Facility, EUFORGEN, and forest inventories, and we developed species distribution models using MaxEnt and 19 bioclimatic variables. Models were developed for three climate change scenarios-optimistic (RCP2.6), moderate (RCP4.5), and pessimistic (RPC8.5)-using three General Circulation Models, for the period 2061-2080. Our study revealed different responses of tree species to projected climate change. The species may be divided into three groups: "winners"-mostly late-successional species: Abies alba, Fagus sylvatica, Fraxinus excelsior, Quercus robur, and Quercus petraea; "losers"-mostly pioneer species: Betula pendula, Larix decidua, Picea abies, and Pinus sylvestris; and alien species-Pseudotsuga menziesii, Quercus rubra, and Robinia pseudoacacia, which may be also considered as "winners." Assuming limited migration, most of the species studied would face a significant decrease in suitable habitat area. The threat level was highest for species that currently have the northernmost distribution centers. Ecological consequences of the projected range contractions would be serious for both forest management and nature conservation.

Functional diversity, succession, and human-mediated disturbances in raised bog vegetation.

Raised and transitional bogs are one of the most threatened types of ecosystem, due to high specialisation of biota, associated with adaptations to severe environmental conditions. The aim of the study was to characterize the relationships between functional diversity (reflecting ecosystem-shaping processes) of raised bog plant communities and successional gradients (expressed as tree dimensions) and to show how impacts of former clear cuts may alter these relationships in two raised bogs in 'Bory Tucholskie' National Park (N Poland). Herbaceous layers of the plant communities were examined by floristic relevés (25m(2)) on systematically established transects. We also assessed patterns of tree ring widths. There were no relationships between vegetation functional diversity components and successional progress: only functional dispersion was negatively, but weakly, correlated with median DBH. Lack of these relationships may be connected with lack of prevalence of habitat filtering and low level of competition over all the successional phases. Former clear cuts, indicated by peaks of tree ring width, influenced the growth of trees in the bogs studied. In the bog with more intensive clear cuts we found more species with higher trophic requirements, which may indicate nutrient influx. However, we did not observe differences in vegetation patterns, functional traits or functional diversity indices between the two bogs studied. We also did not find an influence of clear cut intensity on relationships between functional diversity indices and successional progress. Thus, we found that alteration of the ecosystems studied by neighbourhood clear cuts did not affect the bogs strongly, as the vegetation was resilient to these impacts. Knowledge of vegetation resilience after clear cuts may be crucial for conservation planning in raised bog ecosystems.