Lowland Temperate Forest Research Articles

Changes in plant diversity of European lowland forests: Increased homogenization and expansion of shade-tolerant trees

European lowland forests have undergone significant transformations over the past century due to increased canopy closure, eutrophication and plant invasions. The new millennium has brought plant invasions, alien fungal pathogens, and extreme weather conditions, all contributing to forest diebacks. However, the response of plant diversity remains poorly understood. We examined changes in understorey vegetation following a decade (2012–2021) of severe drought in four temperate lowland forest types (dominated by oaks, hornbeams, ashes, and willows) to understand how water availability, canopy openness, and alien fungal pathogens altered diversity in interaction with climate change. Following an exceptionally warm decade, the vegetation exhibited increased homogeneity, with denser shrub and herb layers, likely resulting from diminished tree canopy, particularly in hornbeam and ash forests. Homogenization was manifested by the colonization of plants with conservative life-history strategies (higher leaf dry matter content) to cope with increased drought. Consequently, communities with fewer species increased their species richness, while species-rich communities experienced impoverishment. Conversely, herbaceous species with higher specific leaf area were declining. Compositional changes were particularly prominent in hornbeam and oakwoods at the drier end of moisture gradient where the understorey became dominated by woody plants. Ashwoods were opening up due to ash dieback by fungal pathogens, causing replacement of wetland forbs by nitrophilous forbs and woody saplings. The overall number of species decreased in oakwoods but increased in hornbeam and ashwoods due to increased cover of grasses and shade-tolerant woody species, mostly Acer campestre. Conversely, willow understorey vegetation at the wetter end of the moisture gradient remained relatively stable. Our findings suggest shifts towards more homogeneous vegetation. Conservation plans for managing the remnants of species-rich lowland forests should consider the accelerated environmental changes linked to canopy alterations, biological invasions, and extreme climate events.

Early response of understory vegetation to the mass dieback of Norway spruce in the European lowland temperate forest

Spruce-dominated forests are commonly exposed to disturbances associated with mass occurrences of bark beetles. The dieback of trees triggers many physical and chemical processes in the ecosystem resulting in rapid changes in the vegetation of the lower forest layers. We aimed to determine the response of non-tree understory vegetation to the mass dieback of Norway spruce (Picea abies) in the first years after the disturbance caused by the European spruce bark beetle (Ips typographus) outbreak. Our study area was the Białowieża Biosphere Reserve covering the Polish part of the emblematic Białowieża Forest, in total 597 ​km2. The main data source comprised 3,900 phytosociological relevés (combined spring and summer campaigns) collected from 1,300 systematically distributed forest sites in 2016–2018 – the peak years of the bark beetle outbreak. We found that the understory responded immediately to mass spruce dieback, with the most pronounced changes observed in the year of the disturbance and the subsequent year. Shade-tolerant forest species declined in the initial years following the mass spruce dieback, while hemicryptophytes, therophytes, light-demanding species associated with non-forest semi-natural communities, as well as water-demanding forest species, expanded. Oxalis acetosella, the most common understory species in the Białowieża Forest, showed a distinct fluctuation pattern, with strong short-term expansion right after spruce dieback, followed by a gradual decline over the next 3–4 years to a cover level 5 percentage points lower than before the disturbance. Thus, our study revealed that mass spruce dieback selectively affects individual herb species, and their responses can be directional and non-directional (fluctuation). Furthermore, we demonstrated that the mass dieback of spruce temporarily increases plant species diversity (α-diversity).

Effects of habitat heterogeneity on bird communities in the forests of northeastern Germany

Habitat heterogeneity is a key factor for regulating biodiversity in temperate lowland forests. Specifically, stands associated with late forest development phases provide important habitat structures for many rare and threatened forest bird species. However, how forest stands that differ in their structural complexity, canopy conditions and tree species composition affect forest bird assemblages both at the local and landscape scale remains largely unclear. In a young moraine lake landscape of northeastern Germany, we assessed correlations of bird diversity and bird composition with stand properties. We used data from 48 transects (400 m) established in (1) unmanaged, closed-canopy, mature stands that were dominated by Fagus sylvatica (UDS), and (2) diverse managed, mixed coniferous stands with a mosaic of open and closed canopy patches (MCS). We found that bird communities of the UDS strongly differed from those in the MCS, with open habitat species being more frequent in the MCS. By contrast, differences in diversity measures were less distinct. Moreover, we identified nine indicator species for the UDS (Columba oenas, Cyanistes caeruleus, Muscicapa striata, Leiopicus medius, Certhia brachydactyla, Ficedula parva, Dryobates minor, Sturnus vulgaris, Ficedula hypoleuca) and seven indicator species for the MCS (Periparus ater, Pyrrhula pyrrhula, Regulus regulus, Prunella modularis, Lophophanus cristatus, Emberiza citronella, Anthus trivialis). Several famous ancient beech forest patches in Müritz National Park and the UNESCO Biosphere Reserve “Schorfheide-Chorin” were found to harbour the set of the UDS indicator species. The UDS support of bird coenosis is typical for old mature broadleaved forests and can be considered as an effective tool for bird conservation. Our results further indicate that the combination of unmanaged and managed stands associated with different habitat complexities would benefit forest bird assemblages at the landscape scale. Key words: forest specialist birds, bird conservation, non-managed forests, old-growth patches, Ficedula parva, Leiopicus medius, coniferous forest

Competition for acoustic space in a temperate-forest bird community.

Animals that communicate by acoustic signaling share a common acoustic environment. Birds are particularly vocal examples, using a wide repertoire of broadcast signals for mate attraction and territorial defense. However, interference caused by sounds that overlap in frequency and time can disrupt signal detection and reduce reproductive success. Here, we investigated competition avoidance mechanisms used by the bird community inhabiting a primeval lowland temperate forest in Białowieża, Eastern Poland. We recorded the dawn chorus at 84 locations in early and late spring and calculated dissimilarity indices of the broadcast signals to examine how species with greater song similarities use spatial and temporal partitioning to avoid competition for acoustic space throughout the breeding season. The bird community changed its use of acoustic space throughout the day and season. Birds did not use spatial partitioning of signal space when we looked at recording locations over the whole study period, but they did in a seasonal context, with species more acoustically different than expected by chance recorded at the same point in the same part of the season. Our results also indicate that daily temporal niche partitioning may only occur at certain times before sunrise, with no evidence of large-scale temporal partitioning between species vocalizing during the same 1-min recordings in daytime. These results contribute toward our understanding of the evolution of bird communication and highlight the strategies employed by different species to improve their signal transmission.

Trait-Based Response of Deadwood and Tree-Related Microhabitats to Decline in Temperate Lowland and Montane Forests

Trait-Based Response of Deadwood and Tree-Related Microhabitats to Decline in Temperate Lowland and Montane Forests

Attitudes toward Conservation of the Transboundary Białowieża Forest among Ecotourism Businesses in Poland and Belarus

The Białowieża Forest is a contested transboundary forest massif in Poland and Belarus. Reflecting on transitions from value chains built on sustained yield forestry to ecotourism, we pioneer documentation of how country-specific legacies shape preferences toward increased forest protection at the expense of wood production. For both countries, we used a quantitative ordered logit model based on questionnaires to Polish and Belarusian ecotourism business owners to, for the first time, empirically study drivers of their preferences toward different Białowieża Forest values, and we used qualitative data to identify attitudes toward the expansion of protected areas in the Białowieża Forest. Whilst Belarusian ecotourism business owners supported increased area protection, the opposite was true for their Polish counterparts. The proportion of foreign guests co-varied with support toward increased area protection. Conversely, local origin, size of hospitality business, and role of foresters as customers decreased interest in area protection. The qualitative data revealed that narratives against extended area protection were spread in Poland but not in Belarus. The conflict over the conservation of the Polish part of the Białowieża Forest involves actors and stakeholders with competing interests. A solution is that this remnant massif of the once widespread European temperate lowland forest becomes subject to a regional planning and zoning perspective. Encouraging multiple value chains and evidence-based collaborative learning are key components.

Acoustic indices estimate breeding bird species richness with daily and seasonally variable effectiveness in lowland temperate Białowieża forest

Acoustic indices have been proposed as rapid and easy to apply tool for biodiversity estimation of vocalising animals without the need for individual species identification. However, inconclusive, or even opposite dependencies between acoustic indices and animal biodiversity found in various studies suggest that their effectiveness is environmentally variable.Here we examined how three acoustic indices: Bioacoustic Index (BI), Acoustic Complexity Index (ACI) and Acoustic Diversity Index (ADI) predict bird species richness in a species-rich, lowland temperate forest in Europe – the Białowieża Forest. We recorded soundscape in early and late spring at 84 recording points. We analysed 72 1-min sound samples collected per recording point to evaluate how well acoustic indices predict bird species richness from the perspective of a single sound sample, survey and recording point and how they follow the daily pattern of singing activity.When we compared the values of acoustic indices with the number of bird species detected manually in 1-min sound samples, we found BI to best predict the bird species richness, independently of time in the season but variably across the day, while ACI and ADI showed weaker dependency, variable both seasonally and daily. The correlation between each index and number of bird species was stronger in the early part of the season. Averaged by survey or recording point, the acoustic indices correlated more strongly with the mean compared to the total bird species richness, and provided better estimation of bird biodiversity in the early than the late survey. At the level of the recording point, BI correlated most strongly with mean bird species richness (rho = 0.584), while ADI correlated most strongly with total bird species richness (rho = -0.347). Acoustic indices followed daily bird activity pattern, yet they provided greater values before the peak of the species richness estimated by manual spectrogram scanning and listening to recordings.In this study acoustic indices correlated moderately to strongly with the bird species richness, providing a useful tool for rapid estimation of bird biodiversity in temperate forests. However, daily and seasonal variation in effectiveness of acoustic indices should be taken into account in the analysis. Using the mean instead of the total number of bird species in comparisons improved the effectiveness of indices but measured different aspects of biodiversity.

Contrasting Responses of Alien and Ancient Forest Indicator Plant Species to Fragmentation Process in the Temperate Lowland Forests.

Fragmentation is one of the major threats to biodiversity. In a fragmented landscape, forest specialists are losing suitable forest habitats with specific site and microclimate conditions, which results in their local extinction. Conversely, the invasion of alien species is facilitated by open forest areas and increased boundaries between forest fragments and adjacent land. We studied the effect of fragmentation in terms of fragment size impact on overall plant species richness and on selected ecologically important groups' richness, composition, and diversity. We surveyed vegetation in the interior of 47 fragments of various sizes and one unfragmented reference forest. Our results reveal that the effect of fragmentation is complex and differs for studied plant groups. Decreasing fragment size negatively affects the overall plant richness and richness of native and ancient forest indicator plants as well as their diversity, while the effect is positive for alien plants. The highest proportion of ancient forest indicator plant species and the lowest proportion of alien plants in the unfragmented forest underline the great conservation value of forest fragments. At the same time, our results reveal that large and diverse forest ecosystems are susceptible to biological invasions as well.

Determinants of invasion by single versus multiple plant species in temperate lowland forests

Determinants of invasion by single versus multiple plant species in temperate lowland forests

Stand Composition, Tree-Related Microhabitats and Birds—A Network of Relationships in a Managed Forest

Forest ecosystems contain many tree-related microhabitats (TreMs), which are used by various groups of organisms. Birds use TreMs for shelter, foraging and breeding. The abundance and variability of TreMs is related to tree stand composition and age. Over the last few centuries there has been a drastic decline in the structural and biological diversity of temperate forests over large areas of the Northern Hemisphere. These changes have reduced the diversity and quantity of TreMs. In this study we showed the relationships between stand composition, the abundance of TreMs, and the species richness of birds in a managed forest. We focused on TreMs that are important to birds: woodpecker breeding cavities, rot holes, dead branches, broken treetops, and perennial polypores. Our study was performed in a managed lowland temperate forest. In 94 plots (10 ha each) we made bird surveys and inventoried the stand composition and TreMs. Our results show that the tree stand composition of a managed forest affects the abundance of TreMs. The share of deciduous trees in the stand favors the occurrence of such TreMs as dead branches, rot holes and perennial polypores. The overall richness of bird species and the species richness of primary cavity nesters depended on the total basal area of oak, hornbeam and birch, whereas the species richness of secondary cavity nesters increased with the total basal area of birch and oak.

Three-dimensional stratification pattern in an old-growth lowland forest: How does height in canopy and season influence temperate bat activity?

The study of animal–habitat interactions is of primary importance for the formulation of conservation recommendations. Flying, gliding, and climbing animals have the ability to exploit their habitat in a three‐dimensional way, and the vertical canopy structure in forests plays an essential role for habitat suitability. Forest bats as flying mammals may seasonally shift their microhabitat use due to differing energy demands or changing prey availability, but the patterns are not well understood. We investigated three‐dimensional and seasonal habitat use by insectivorous bats in a temperate lowland old‐growth forest, the Belovezhskaya Pushcha in Belarus. We acoustically sampled broadleaved and mixed coniferous plots in the forest interior and in gaps in three heights during two reproductive periods (pregnancy/lactation vs. postlactation). In canopy gaps, vertical stratification in bat activity was less pronounced than in the forest interior. Vertical activity patterns differed among species. The upper canopy levels were important foraging habitats for the open‐space forager guild and for some edge‐space foragers like the Barbastelle bat Barbastella barbastellus and the soprano pipistrelle Pipistrellus pygmaeus. Myotis species had highest activity levels near the ground in forest gaps. Moreover, we found species‐dependent seasonal microhabitat shifts. Generally, all species and species groups considered except Myotis species showed higher activity levels during postlactation. Myotis species tended toward higher activity in the forest interior during postlactation. P. pygmaeus switched from high activity levels in the upper canopy during pregnancy and lactation to high activity levels near the ground during postlactation. We conclude that a full comprehension of forest bat habitat use is only possible when height in canopy and seasonal patterns are considered.

Mature stand developmental stage has ceased to constitute the most suitable habitat for the capercaillie in the August\xf3w Forest, Poland

BackgroundForest management affects the habitat conditions for many forest-dwelling species. Among them, the capercaillie (Tetrao urogallus) is a rare forest grouse inhabiting old, mature forests. We compared the structure of forest habitat among 9 active and 9 abandoned leks in the Augustów Forest (North-Eastern Poland), within a radius of 1 km of the leks, defined as the Key Areas for the capercaillie in lowland temperate forest. Habitat measurements were conducted on 1779 circular plots. Assessments made on all plots related to 13 habitat variables measured or noted in the field, including stand structure, canopy closure, stand developmental stage, percentage of Scots pine (Pinus sylvestris), soil fertility and soil moisture, the share of undergrowth, the cover of shrubs, the cover of bilberry (Vaccinium sp.), and the presence of certain habitat elements important to the capercaillie.ResultsTo compare the still-occupied and the abandoned KAs for the capercaillie, a logistic regression model was developed. The variables best explaining differences between these two categories were: the occurrence of undergrowth layers, canopy closure in the second canopy layer, and stand age. According to the model, with the increase of the shrub-layer cover as well as the density of trees, the probability of the presence of the capercaillie decreased. The capercaillie in the area of the Augustów Forest occupy mainly dry and poor, middle-aged, pine-dominated forests, with a moderate extent of stand canopy closure and only weakly-developed layers of undergrowth.ConclusionsThe filling-in of mature stands with sub-canopy trees and shrubs (the process which is stimulated by climate change and site eutrophication) causes structural changes, which are unfavourable to the capercaillie. This might explain why in the course of the recent decades the capercaillie has abandoned the oldest stands, distinguished by the presence of bigger shares of undergrowth. The capercaillie has shifted to younger stands, which reveal a lesser extent of canopy closure and a more limited development of understorey vegetation.

Population ecology and dynamics of a remnant natural population of European yew Taxus baccata in a lowland temperate forest – implications for use in reforestation

There is increasing focus on reforestation, but the efforts still often include limited subsets of species despite evidence that tree diversity promote biodiversity and ecological resilience. In addition to these benefits, greater inclusion of rare native species in reforestation efforts would also help conserve these species in an uncertain future. Here, we investigate the population ecology and dynamics of the only remaining historical population of the shade‐adapted under‐ and mid‐story tree European yew Taxus baccata in Denmark to inform its potential usage in reforestation. The species has been widely extirpated from European landscapes, and while much used in horticulture, is hardly used in reforestation, so there is limited experience with its requirements and performance. We collected data on all individuals in 2015 and compared them with results from a previous census in 1999. Furthermore, we used boosted regression trees (BRT) modelling to investigate the ecological drivers of the distributions of its different life stages. Our results show a stable T. baccata population, with much regeneration in areas of more open‐canopy conditions that also support high survival between life‐stages. The BRT results show that moss‐dominated microhabitats under moderately shaded conditions are important for T. baccata seedling establishment, while higher light availability is important for survival from sapling to adult life‐stages. For use in reforestation, we recommend providing moderately shaded microhabitats to allow the seedlings and small saplings to escape competition while also acting as protection from herbivores. Through their long‐lived nature, low stature and evergreen foliage, T. baccata would increase the structural complexity of young woodlands, likely enhancing their value for biodiversity, their ecological resilience, as well as their amenity value. Inclusion of T. baccata in reforestation efforts would also aid its spontaneous recolonization of woodland areas, helping it to build larger, more widespread populations with greater resilience to future pressures.

Mechanisms of community assembly explaining beta‐diversity patterns across biogeographic regions

AbstractAimWe examined tree beta diversity in four biogeographical regions with contrasting environmental conditions, latitude, and diversity. We tested: (a) the influence of the species pool on beta diversity; (b) the relative contribution of niche‐based and dispersal‐based assembly to beta diversity; and (c) differences in the importance of these two assembly mechanisms in regions with differing productivity and species richness.LocationLowland and montane tropical forests in the Madidi region (Bolivia), lowland temperate forests in the Ozarks (USA), and montane temperate forests in the Cantabrian Mountains (Spain).MethodsWe surveyed woody plants with a diameter ≥2.5 cm following a standardized protocol in 236 0.1‐ha forest plots in four different biogeographical regions. We estimated the species pool at each region and used it to recreate null communities determined entirely by the species pool. Observed patterns of beta diversity smaller or greater than the null‐expected patterns of beta diversity implies the presence of local assembly mechanisms beyond the influence of the species pool. We used variation‐partitioning analyses to compare the contribution of niche‐based and dispersal‐based assembly to patterns of observed beta diversity and their deviations from null models among the four regions.Results(a) Differences in species pools alone did not explain observed differences in beta diversity among biogeographic regions. (b) In 3/4 regions, the environment explained more of the variation in beta diversity than spatial variables. (c) Spatial variables explained more of the beta diversity in more diverse and more productive regions with more rare species (tropical and lower‐elevation regions) compared to less diverse and less productive regions (temperate and higher‐elevation regions). (d) Greater alpha or gamma diversity did not result in higher beta diversity or stronger correlations with the environment.ConclusionOverall, the observed differences in beta diversity are better explained by differences in community assembly mechanism than by biogeographical processes that shaped the species pool.

Root Plates as Nesting Sites for Eurasian Wrens Troglodytes troglodytes in a Forest Undergoing Renaturalisation

Upturned root systems are used by several species of birds as nesting sites. The primeval lowland temperate forests are the crucial the source of information with this respect. The aim of the study was to characterise the root plates as nesting sites in a forest covered by a reserve protection system for about 20 years. The research was conducted between 2016–2018 in south-eastern Poland. In the area examined, nests of the Eurasian Wren Troglodytes troglodytes and the European Robin Erithacus rubecula were found to occupy 19.9% and 2.1% of root plates in uprooted trees, respectively. Among root plates with wren nest, Scots Pine accounted 36.8%, subsequently Norway Spruce 28.9%, and Silver Birch 18.4%. Inclined root plate and root plate of large surface were often chosen by Wrens for building a nest. A week positive correlation was found between the height at which the nest was built and the height of the root plate.

Natural and anthropogenic factors influencing the bat community in commercial tree stands in a temperate lowland forest of natural origin (Białowieża Forest)

In 2011–2017, we examined the ecology of bat assemblages in the commercially used stands of the Białowieża Forest, Poland. The species composition was analyzed, as well as the relationship between bat activity and distance to buildings and to open waters. The relationship between bat activity and stand age, type of stand (coniferous vs. deciduous), and tree canopy closure (open vs. dense) was also examined. Bat activity was recorded using full-spectrum ultrasound detectors, with subsequent analysis using specialized software. Bats were recorded on eight linear transects. The following species of bats were found: western barbastelle (Barbastella barbastellus), serotine (Eptesicus serotinus), northern bat (Eptesicus nilssoni), common noctule (Nyctalus noctula), lesser noctule (Nyctalus leisleri), soprano pipistrelle (Pipistrellus pygmaeus), Nathusius’ pipistrelle (Pipistrellus nathusii), common pipistrelle (Pipistrellus pipistrellus), parti-coloured bat (Vespertilio murinus), and bats from the genus Myotis. Bat activity was affected mainly by the canopy structure along a transect, the number of dead trees, and the age of tree stands. The activity of three from five studied open space aerial foraging bat species (serotine bat, northern bat, and parti-coloured bat) was negatively affected by canopy closure along a transect. Canopy cover was not the most important factor for the other two open space bat species - the common noctule and lesser noctule. Canopy closure was also not a primary factor affecting the edge space foragers like species from this genus Pipistrellus. The activity of Nathusius’ pipistrelle was positively correlated with the number of nearby dead trees, whereas the activity of the common pipistrelle was negatively correlated with the upper quartile of trees age. There was no good single environmental variable for the activity of western barbastelle, bats of the genus Myotis and the soprano pipistrelle. However, we found that the activity of western barbastelle and soprano pipistrelle clearly increased among years. The results suggest that commercial forests with limited economic activity are still a suitable environment for forest bats, including rare and endangered species. They also show that the transformation of stands, resulting in anthropogenic open areas, as well as forest roads, allows synanthropic species to penetrate deep into compact stands. We still do not fully know the impact of such a transformation of the fauna on the forest ecosystem, including the impact on vulnerable bat species closely related to forests.

Diversity and abundance of large tree holes used by Tawny Owls Strix aluco in lowland temperate forests

ABSTRACT Capsule Tawny Owls Strix aluco used a wide variety of tree holes for roosting, but only a minority were used for nesting, which comprised those holes at greater heights in larger trees and with a flat base. Aims We aimed to determine the type and dimensions of tree holes used by Tawny Owls for roosting and nesting, including which tree species were the most important hole providers, and the density of tree holes available for Tawny Owls in forests of different age classes. Methods We conducted visual searches for all large tree holes within study plots, recorded their measurements and signs of use, comparing the features of used and unused holes. Data were collected in medium-aged and old-growth forests (Ukraine, Homilsha Forest, 750 ha, 10 seasons) and in primeval forest (Poland, Białowieża Forest, 150 ha, 2 seasons). Results Roosting holes came in a wide variety of shapes and sizes, frequently being very deep and with an uneven base. Hole entrances needed to be over 10 cm wide and the hollows more than 20 cm deep, presumably to enable owls to enter and evade predators. All nesting holes had a flat base and were located in larger trees, at greater heights than roosting holes. Old trees of low commercial timber value (European Hornbeam Carpinus betulus, Small-leaved Lime Tilia cordata, European Pear Pyrus communis) were the most important hole providers. Suitable holes were found in trees of at least 80 years old, and their abundance increased with tree age, exceeding 50 holes/km2 in the primeval forest. Conclusion Despite the abundance of suitable roosting holes, nesting holes remained a rare resource associated with larger, older trees. As tree species of low economic value were the main hole providers, these should be retained in forestry operations.

Natural and human-related determinants of dead wood quantity and quality in a managed European lowland temperate forest

Much is known about the minimum thresholds for dead wood that would ensure the persistence of saproxylic organisms and maintain the overall biodiversity of forest ecosystems, but reaching those thresholds is still a challenge in forests where nature conservation is not the sole goal (e.g., Natura 2000 forests managed for timber). Understanding what determines the quantity and quality of dead wood in managed forests is a prerequisite for developing methods to increase its retention without decreasing a forest’s production. We surveyed the volume, number, stage of decay, and species identity of standing and lying coarse woody debris (CWD) in 183 stands in a complex of lowland Natura 2000 forests in southern Poland, and then determined the relationships between these parameters and tree stand structure, intensity of previous silviculture interventions, accessibility of terrain, and local community impact. CWD volume varied from 0.1 to 66.3 m3 ha−1 (average 6.9 m3 ha−1), which is up to several times less than the recommended thresholds. Large-sized CWD and CWD of species known to support rich communities of saproxylic organisms (e.g., Carpinus betulus) were clearly underrepresented. Wood of economically less valuable species was often left in the forest, which boosted the diversity of CWD microhabitats. CWD quantity and quality was significantly shaped by both natural and human-related factors. Among the latter, harvesting intensity and proximity to human settlements affected CWD negatively, while terrain-related difficulties (distance to roads, watercourse density) affected it positively. Surprisingly, the site accessibility effect was important even though the studied area is level and covered by a dense road network. The results suggest that cost-effective CWD management plans for Natura 2000 forests, or, more broadly, multifunctional forests, should discourage some practices accompanying timber harvesting (e.g., fragmenting of pieces of aged CWD), promote practices that positively affect CWD (e.g., not harvesting low-value timber), and set aside small areas to accelerate CWD retention. These things should be done wherever their effects are unlikely to be reversed, i.e., at sites difficult for forestry vehicles to access and away from human settlements.

Saproxylic beetles in tropical and temperate forests – A standardized comparison of vertical stratification patterns

Forests are complex three-dimensional ecosystems, but little is known about the influence of vertical stratification of forest structure on biodiversity and species turnover. Saproxylic beetles make a substantial contribution to forest biodiversity and ecosystem functions such as nutrient cycling. Management measures aimed at supporting saproxylic biodiversity are becoming an integral part of sustainable forest management practices. Yet, monitoring is carried out under the assumption that saproxylic activity at ground level will be a realistic reflection of saproxylic biodiversity in the forest as a whole.To investigate the validity of this assumption we compare vertical stratification and composition of saproxylic beetle assemblages between three forest types of varying altitude and latitude, including a tropical lowland forest in Panama, a temperate lowland forest and a temperate montane forest, both in the eastern Czech Republic. Beetles were sampled following a standardized sampling protocol using flight intercept traps arranged in vertical transects.Overall, the tropical forest was estimated to harbour two to three times more saproxylic beetle species than the temperate lowland and the montane forest, respectively. However, point richness estimates within vertical strata were remarkably similar between biomes. Species richness was similar in the understorey of all three forests. It peaked in the canopy of the tropical forest but in the understorey of temperate forests. So, while the beetle assemblages were clearly vertically stratified in all three forest types, stratification patterns varied markedly between tropical and temperate forests. This trend is driven primarily by the high richness of saproxylic beetles in the tropical forest canopy. However these richness differences belie the strong similarities in stratification of feeding guild composition observed all three forest types. This would tend to suggest that similar trophic structuring forces might operate across very different forest biomes of the world.Similarities in feeding guild composition suggest that management measures aiming at conserving biodiversity of saproxylic beetles are likely to be effective across different forest types. The differences in vertical stratification, however, suggest that understorey monitoring alone will be insufficient to understand management effects on saproxylic biodiversity. In the tropics, in particular, more emphasis will need to be placed on managing the diverse, three-dimensional structure of forest canopies as habitat for saproxylic beetles.

Is the impact of loggings in the last primeval lowland forest in Europe underestimated? The conservation issues of Białowieża Forest

Loggings in biodiversity hot-spots are perceived as very serious threat to forest species and habitats of high conservation interest. In this paper we scrutinize the spatial impacts of recent loggings in the Polish part of the renowned Białowieża Forest being the last remaining area of lowland temperate forest with a primeval character in Europe with the status of World Heritage and Natura 2000 site. The loggings have been applied in order to cope with the outbreak of the spruce bark beetle Ips typographus. We used satellite images to perform cover change detection analysis that delineated areas being logged in Białowieża Forest between July 2015 and June 2018. Next, we assessed the extent of forest loss in areas with different management regimes as well as landscape-scale impacts. The total area of detected clear-cuts amounted to at least 675 ha, including 229 ha of old-growth stands. Assuming a buffer of 100 m from the edge of cleared forest patches, the cumulative direct and indirect impact of recent logging activities was estimated to amount to at least 4073 ha of affected forest. Logging activities resulted in a 26% increase in fragmentation in the entire Natura 2000 area. We argue that the ecological impact of logging extends beyond the logged areas by modifying the landscape structure and affecting ecosystem functioning on a landscape scale. As such, the recent salvage loggings in the Białowieża Forest clearly damaged the conservation value of this precious area, not in the least by increasing its fragmentation. To avoid further degradation, we strongly argue for allowing natural tree regeneration on clear cuts and also for the extension of Białowieża National Park to cover the entire forested area.