Coniferous Stands Research Articles

Bryophyte community responses 20 years after forest management in boreal mixedwood forest

Sustainable forest management relies on a diversity of harvesting practices to conserve the variety of stand structures and compositions found in natural forests. Extensive use of clearcuts can homogenize stand structure by removing all the canopy, damage forest soils and destroy older downed woody debris already present within stands. In contrast partial cuts maintain some standing overstory and conserve certain biological legacies like large live trees as well as standing and downed dead wood, and thus should better conserve biodiversity. However, given the large number of species potentially affected by harvest operations, balancing harvesting intensity and conservation of biodiversity requires a clear understanding of habitat requirements of resident organisms and species conservation post-harvest. We examined the impacts of increasing intensities of stem removal (33%, 40%, 66% and 100%) 20 years after harvest on bryophyte communities in three stand types common in the succession sequences of Eastern boreal mixedwood forests that were dominated by trembling aspen, mixedwood and conifers. While many generalist and common forest species were shared among all harvesting levels and forest types, more specialized species like liverworts differed strongly between uncut and clearcut stands and less between uncut and partial cut stands. Bryophyte species in hardwood dominated stands tolerated more fluctuations in environmental conditions than species in mixed stands. We were unable to find habitat specialists typically associated with coniferous stands and may be related to prior outbreaks of spruce budworm that occurred 30 years ago. Our results highlight how harvest intensity and forest stand type interact to affect bryophytes and how intact stands may be required to conserve many species that are sensitive to any degree of harvesting.

Do admixed conifers change soil nutrient conditions of European beech stands?

Context Establishing mixed forest stands is an option for improving soil nutrient conditions and for increasing the resilience of forest ecosystems. Aims Identify the effects on soil chemistry of spruce and Douglas fir admixed in European beech forest. Methods We analysed pure and mixed species stands in Germany. The pure stands were mature European beech (Fagus sylvatica), Douglas fir (Pseudotsuga menziesii), and Norway spruce (Picea abies). The mixtures were composed of beech with either Douglas fir or spruce. The stands were located in two regions with different soil conditions. Results Our results indicated that pure spruce stands, independent of site condition, had the lowest base saturation while beech showed the highest values. The impact of Douglas fir differed between site conditions. On sandy soils, there was higher pH and base saturation under Douglas fir than under spruce. On loamy soils, however, the pH under Douglas fir and beech was lower than under spruce. The cation stocks (Ca and Mg) on sandy soils were lower under spruce and spruce/beech stands than under Douglas fir and beech. In contrast, under loamy soil, exchangeable Ca and Mg stocks were less under beech than under spruce stands. Soil exchangeable K under mixed stands was among the highest compared to pure stands, independent of site condition. Conclusions Mixed species stands reduce soil base cation depletion compared to conifer stands. Implications Admixture of Douglas fir to European beech seems to be a more reasonable option for forest management than an admixture of spruce, since it does not negatively affect soil chemistry.

Reconstruction of the dynamics of the dark coniferous forests of the Teberdinsky Nature Reserve and prospects for their natural recovery after mass drying out

A study was made of the mass drying of the eastern spruce (Picea orientalis (L.) Link) in the Teberdinsky Nature Reserve (North Caucasus). The main cause of the drying was an outbreak of the number of bark beetle (Ips typographus L.) whose mass reproduction occurred in the hot seasons of 2012 and 2015. The existing undergrowth was not affected. By 2019, 7 years after the beginning of the mass drying of spruce, most of the groups of drying had died out, single active bark beetle foci were noted. There are almost no live spruces of the upper tiers left. In small numbers, they have been preserved in the Dombai forestry in mixed stands of Picea orientalis (L.) Link, Abies nordmanniana (Stev.) Spach and Fagus orientalis Lipsky. As our study showed, the stands of two of the four forest areas of the reserve originated in a treeless space (250 and 350 years ago). Subsequently, three of the four underwent one strong, but local disturbance during their existence. Reconstruction of the history of dark coniferous stands of the surveyed forest areas shows a high ability for natural self-healing of the Teberdinsky fir-spruce forests after massive disturbances. In the near future (after the fall of dead wood, which is already happening), the stands of sample plots will be a sparse forest from Abies or Abies with Fagus, and most of the sample plots will become open stands with single Abies trees. The modern mass drying of the eastern spruce as a result of bark-borne epiphytotics has a much larger scale of disturbances both in the area and in the degree of destruction of the stand. This is fundamentally different from the disturbances of the past. In such a situation, the shortage of seeds will have a particularly negative impact. Therefore, the preservation of preliminary coniferous undergrowth is especially important.

The Long-Lasting Territories of Forest Apex Predators Sustain Diverse Bird Communities throughout the Year

Apex predators, such as raptors, are used as surrogates to attain conservation objectives; however, their presence in a particular area does not necessarily mean long-term occurrence. Here we used data on long-lasting (20–40 years) territories of two generalist raptors: the diurnal Northern goshawk and the nocturnal Ural owl in deciduous and coniferous forests of southern Poland to assess their role as hotspots of bird diversity. Species richness and abundance of birds were much higher in the long-lasting territories of both apex predators than in random never-occupied sites and this pattern was common for breeding and wintering periods. These differences were more pronounced in deciduous than coniferous stands. Rare bird species (e.g., annexed in the Bird Directive of the European Parliament and of the Council on the conservation of wild birds such as some woodpeckers and flycatchers) were found to be particularly associated with long-lasting territories of raptors. Long-lasting territories were also characterized by greater forest habitat quality (e.g., higher number of old trees and deadwood) with lower management intensity. These results strongly point to the role of long-lasting territories of raptors as surrogates of biodiversity. Such territories, if known in forests, could be excellent for the designation of protected areas or logging there should at least be reduced to allow for the continuous breeding of apex predators and associated bird assemblages.

Site occupancy by American martens and fishers in temperate deciduous forests of Québec.

Interspecific interactions can mediate site occupancy of sympatric species and can be a key factor in habitat use patterns. American martens (Martes americana) and Fishers (Pekania pennanti) are two sympatric mesocarnivores in eastern North American forests. Due to their larger size, fishers have a competitive advantage over martens. We investigated site occupancy of martens and fishers in temperate deciduous forests of Québec, an environment modified by forest management and climate change. We formulated hypotheses on the spatial distribution of the studied species based on the knowledge of local trappers and on the scientific literature regarding forest cover composition, habitat fragmentation, and competitive relationships. We used a network of 49 camera traps monitored over two fall seasons to document site occupancy by both species. We used two-species site occupancy models to assess habitat use and the influence of fishers on martens at spatial grains of different sizes. None of the habitat variables that we considered explained site occupancy by fishers. Availability of dense old coniferous stands explained the spatial distribution of martens both at the home range grain size and at the landscape grain size. We identified the characteristics of habitat hotspots based on the knowledge of trappers, which highlighted the importance of stand composition, height, age, and canopy closure. The characteristics of habitat hotspots for martens in temperate deciduous forests refine the habitat suitability model for American martens that was originally developed for boreal forests of Québec.

Long-Term Changes in Breeding Bird Community of a Primeval Temperate Forest: 45 years of Censuses in the Białowieża National Park (Poland)

This paper reports the long-term numerical trends of the thirty common forest bird species and explores changes in the community composition in the three main types of old-growth stands in the Białowieża National Park (E Poland, hereafter BNP) over 45 years (1975–2019). We present recent (2015–2019) data on abundance of birds for the seven study plots and pool them with the time series collected since 1975. The numbers of individual bird species strongly fluctuated, with most of the species showing alternating phases (the initial periods of population growth followed by the periods of population decline or stability). The numbers of 19 species increased; maximum growths by c. 3–5% per year included Columba palumbus, Dendrocopos major, Sylvia atricapilla and Regulus ignicapilla. Among a few declining species, Ficedula hypoleuca, Phylloscopus sibilatrix and F. parva experienced the strongest declines, respectively by 4.0%, 2.7% and 2.2% per year. Mostly the same species bred in the plots in the 1970s and in recent years, indicating a stable species pool. The total abundance peaked around 2005, declining thereafter in deciduous stands, but increasing further (along with the species richness) in the coniferous stands. The similarity index between the study plots (beta-diversity) changed little over 45 years; ash-alder and lime-hornbeam stands remained most similar, while coniferous forests stood more apart. The changes found in the old-growth stands of BNP (mostly coniferous fragments) could be partly explained by natural modification of the habitat structure and the processes acting in the large geographical scales, within or outside of the breeding grounds. The long-term studies such as the one in the BNP reported here, provide a basis for the rates of natural turnover in the bird communities in pristine habitats, directly unaffected by human impact.

Effect of forest structures and tree species composition on common tick (Ixodes ricinus) abundance—Case study from Czechia

Tick-borne diseases are a significant health problem worldwide and have become even more pervasive in Europe due to the increasing abundance of tick species, especially the common tick (Ixodes ricinus L.). Moreover, in recent years, there have been changes in tick geographical distribution, the occurrence of new tick species, and an expansion in abundance driven by changes in forest management and climate change. Therefore, this paper’s objective is to determine the effect of tree species composition and forest structure on the abundance of I. ricinus in various forest stands in Czechia. Altogether, we analyzed 4195 collected ticks on 56 monitored research plots, of which 4182 individuals were I. ricinus, 4 individuals were Dermacentor reticulatus Fabricius, and 7 individuals were Haemaphysalis concinna C. L. Koch. The average density reached 1.21 ticks per 10 m2. The highest I. ricinus abundance was observed in coniferous stands (especially in Scotch pine—Pinus sylvestris L.) and forest edges with a high incidence of wild ungulate habitat signs. Contrarily, the lowest tick numbers were in clear-cut biotopes and mixed stands. Increasing vertical structure had a significant (p < 0.05) negative effect on I. ricinus abundance, similar to tree species diversity (richness, evenness, heterogeneity) and complex stand diversity on nymph stage abundance. Close-to-nature silviculture of mixed forests, which are resistant to climate extremes, could reduce the tick abundance, as well as the presence of tick-borne diseases compared to standard coniferous monocultures, which are receding now due to climate change. Based on this knowledge, it should be possible to predict the I. ricinus abundance under changing environmental conditions in the Central European region.

Balsam Fir (Abies balsamea (L.) Mill.) Wood Quality after Defoliation by Spruce Budworm (Choristoneura fumiferana Clem.) in the Boreal Forest of Quebec, Canada

Eastern spruce budworm (Choristoneura fumiferana Clem.) is considered the most important disturbing insect in coniferous stands in eastern North America. During an outbreak, spruce budworm can cause severe defoliation in balsam fir (Abies balsamea (L.) Mill.), which can affect wood properties such as moisture content and mechanical properties. This project aimed to assess the influence of the duration of spruce budworm defoliation on the wood quality of mature balsam fir trees. To do this, we studied sapwood proportion, decay, moisture content, mechanical properties and tracheid dimensions in stands that had suffered three, four or five years of defoliation. We also compared living and dead balsam firs and evaluated the change in wood properties with time. Our results showed that dead balsam firs suffered from a loss of wood quality rapidly after their death, particularly in terms of moisture content and decay in the sapwood. Sapwood proportion was similar between living and dead trees, but the sapwood of dead trees contained more decay and had a lower moisture content than living trees. Mechanical properties and tracheid dimensions were 10% and 4% lower in dead trees than in living trees. We did not observe any major differences in wood properties between the three durations of defoliation, suggesting that wood degradation occurs before that. The study did not make it possible to determine the optimal duration of defoliation to harvest the stands.

State of the raw wood growing stocks and prediction of further development of cutting in the context of coniferous stands calamity in the Czech Republic

The extremely dynamic development of calamities caused by the effects of global climate change followed by the spread of under-bark insect pests mainly in coniferous stands and the ongoing incidental felling have raised concerns in the woodworking industry about the developments in the source material with respect to ensuring production in a short-term view. Since the overall standing stock in spruce stands of all age classes in the Czech Republic amounts to 399.6 million m&lt;sup&gt;3&lt;/sup&gt; (2017–2026) and the theoretical outlook of the logging potential based on the percentage of logging accounts for 112.62 million m&lt;sup&gt;3&lt;/sup&gt; (2017–2026), the concerns might be deemed justified. The article presents an updated view of the current situation based on official statistics and offers an analytic prediction of the possible development, considering the possible consequences, even in the production of the forestry sector. The statistical data on the current situation have been compiled for the last two decades of development. The results show that with a continued high rate of bark beetle calamities, assuming a total annual cutting with a permanent limitation on the planned harvests of more than 30 million m&lt;sup&gt;3&lt;/sup&gt;, the complete stands of spruce from age class 5 onwards could be harvested in approximately 14–16 years.

Impact of Arginine Containing Fertilizer on Nitrogen Isotope Ratio and Elemental Content in Young Conifer Stands

A balance between forest growth and deforestation must be maintained to ensure sustainable wood production. Faster forest growth increases the economic benefit and to achieve faster forest growth it should be provided with nutrients from which one of the most important is nitrogen. In this study, nitrogen isotope ratio and elemental concentrations were determined in samples of pine needles, which were collected in plots where nitrogen-containing soil improver (arginine phosphate) was used, as well as in plots without additional nitrogen input. The aim of the study was to evaluate the effect of arginine-containing soil improvers on the nitrogen and other element content in pine needles harvested from selected plots. The obtained results indicate that arginine phosphate fertilizer was taken up by pine seedlings - an increase in nitrogen (0.05% for control samples and 0.7% for samples applied with a soil improver) and a decrease in nitrogen isotope ratio were observed.

The future of Viscum album L. in Europe will be shaped by temperature and host availability

Viscum album L. is a plant of great importance due to its influence on the host trees and, by extension, entire ecosystems. The species is also significant to humans—on the one hand, because of its use in medicine, and on the other, because of the growing threat it poses to the stability of conifer stands. Therefore, it is important to recognize the future range of three mistletoe subspecies (Viscum album subsp. album, V. album subsp. austriacum, and V. album subsp. abietis). Modelling of the potential range of these subspecies was performed using MAXENT software. Locations were collected from literature and databases. A total number of 3335 stands were used. Bioclimatic data for the current conditions and three future scenarios (SSP 1.26, SSP 3.70, SSP 5.85) were downloaded from the CHELSA database. The results confirmed that the temperature is the key variable on the potential range of the analysed subspecies. V. album subsp. abietis is withdrawing from its range according to all scenarios. In the case of V. album subsp. austriacum, a slight range shift is visible. Only the V. album subsp. album will expand non-directionally. The reason is most likely a very large number of host species and greater genetic variability compared to the subspecies found on conifers.

Soil Organic Matter Fractions in Relation to Root Characteristics of Different Tree Species in Altitude Gradient of Temperate Forest in Carpathian Mountains

The roots are a key functional component of belowground systems and one of the main factors influencing the quality and quantity of soil organic matter. Our research aimed to determine the fractional composition of the soil organic matter (SOM) in soils under various tree species on an altitude gradient. In our research, we related the SOM fractions with the root characteristics. There is a lack of information on the relationship between the SOM fractions and the root properties. We assessed labile and heavy fractions of SOM content in forest mountain soils with a climosequence approach. The study plots were established at 600, 800, and 1000 m above sea level in a beech stand (Fagus sylvatica L.) and a fir stand (Abies alba Mill.). In this case, three research plots with beech and fir were designated in each altitude variant. Forest stands growing in the same soil conditions were selected for the study. The research used stands of similar age with the same tree canopy density. The basic physicochemical properties (pH, hydrolytic acidity, carbon and nitrogen content, base cations content) and the fractional composition of the SOM were determined from soil samples. In addition, we determined the basic characteristics of the roots (diameter, length, biomass, decomposition, production). The correlation between soil organic matter fractions and root characteristics was recorded. This study confirmed the importance of climatic conditions in shaping the fractional composition of forest soils. In the highest locations, characterized by lower temperatures, the light fraction of the SOM exhibited the highest C and N content, which is the effect of slower decomposition processes. Apart from climatic conditions, the stabilization of SOM is influenced by the tree species composition of a forest stand. Beech forest stands lead to a larger accumulation of a heavy fraction of SOM. This study indicates a positive correlation between the light fraction of SOM, root biomass, and decomposition rate of roots. Our research shows that avoiding single-species coniferous stands and introducing admixtures of deciduous species, which increase the heavy SOM fraction, is justified in forest management.

Effect of Species Composition on Growth and Yield in Mixed Beech–Coniferous Stands

Research Highlights: In mixed stands, competitive and supportive relationships occur between trees, illustrated by their dendrometric characteristics. Background and Objectives: We investigated the effect of species composition on growth and yield in mixed beech–coniferous stands in the Romanian Carpathians. Materials and Methods: We selected sites with similar trophicity levels, as determined by the site mapping method. Under the same site conditions, we generated models to determine, for each species (spruce, fir, and beech), the main parameters of the site index, including mean height, dominant height, standing volume yield, and mean annual volume increment for different compositional species proportions (psp) and categories of proportions (i.e., low psp, between 10 and 50%, and high psp, ranging between 60 and 90%). Results: Overall, up to the age of 100 years, mixed stands with low psp had enhanced tree height growth, characterized by mean values 2.2% higher for spruce and 4.8% higher for fir and beech. Dominant height showed similar values, regardless of psp. Mixed stands in which the psp increased (i.e., psp &gt; 50) were more productive, with the mean yield differences at the age of 100 years ranging from +1.7% (for fir) to +3.8% (for spruce and beech), increasing to +6% at 140 years. Conclusions: When setting management targets, the management of mixed forests should be based on an understanding of the relationship between the site, species ecological requirements, and their yield potential. Mixed stands can influence individual tree growth and stand yield through psp.

Tree mixtures mediate negative effects of introduced tree species on bird taxonomic and functional diversity

Abstract Recent biodiversity loss has emphasized the necessity to critically evaluate the consequences of human alterations of forest ecosystems. Stand diversification via tree species mixtures and the use of non‐native trees are two such alterations currently gaining importance as climate change adaptations. However, the effects of local versus regional tree mixing on associated biodiversity and notably the modifying role of tree species growing outside their natural range remain poorly understood. We assessed how monocultures and mixtures of native and introduced tree species influence the taxonomic and functional diversity of bird communities at stand and landscape scales in north‐west Germany. We focused on the dominant natural tree species (Fagus sylvatica) and economically important conifer species planted outside their natural range (the native Picea abies and non‐native Pseudotsuga menziesii). We found that bird species richness and functional diversity were generally higher in pure and mixed stands of native F. sylvatica than in pure conifer stands, especially in comparison to non‐native P. menziesii. These differences were particularly strong at the landscape scale. Pure conifer stands harboured only a reduced set of functionally similar bird species. Structural diversity based on tree microhabitat availability emerged as a key predictor of bird diversity. Synthesis and applications. Our study suggests that tree species mixtures do not necessarily increase bird diversity compared to pure stands of native trees, but can promote bird diversity relative to pure stands of species planted outside their natural range. Moreover, local mixtures, rather than a mosaic of pure stands, may promote bird diversity also at the landscape scale. By contrast, pure stands of tree species planted outside their natural range can increase biotic homogenization of forest birds. Promoting structural diversity of microhabitats via tree retention and ensuring that non‐native trees are planted in mixtures with native trees may alleviate potential limitations of climate change‐oriented management for biodiversity.

Management of Recreational Forests in the Romanian Carpathians

Research Highlights: Forests, due to their aesthetic properties, have huge recreational potential, but their management must take into account the requirements of all parties interested in these services. Background and Objectives: We sought to determine the main indicators that characterize the structural diversity of a recreational mountain forest, with relevance for the management of these forests, given that they fulfill multiple functions. Materials and Methods: The structure of 446 stands was investigated and the Shannon (H) diversity index was applied at the level of species (Hsp), age (Hage), tree diameter (Hdg), and tree height (Hhg). Results: Beech occupied 49% of the forest area and fir and spruce 16% each. Generations of trees older than 100 years occupied 71% of the forest area and those older than 150 years occupied 10%. At an age of 120 years, the beech reached a diameter (d, at breast height) of 45 cm and the fir 52 cm. At the forest level, Hsp had a value of 1.63, Hdg of 3.17, and Hhg of 2.76. At the stand level, Hsp reached 1.54, while Hdg and Hhg reached 1.72. Mixed beech–coniferous stands had the greatest diversity. High values of 1.00 for Hsp were determined for 18% of the stands, for Hdg 38%, and for Hhg 35%. Conclusions: Stand structures are in a continuous state of change, so diversity indices can be used to monitor structural and species diversities and to evaluate the recreational potential of stands and forests. A compatibility between the aesthetic qualities of Romanian forests, which is a priority, and the other protection and production services they offer can be achieved by leading the forest stands toward a selection system.

End of the road: Short-term responses of a large mammal community to forest road decommissioning

Anthropogenic disturbances are increasing worldwide, causing wildlife habitat loss, alteration, and fragmentation. In Canada, the decommissioning of linear anthropogenic structures is identified as a promising tool to restore the habitat of threatened populations of boreal caribou (Rangifer tarandus caribou) by reducing food availability for alternate prey and decreasing encounter probabilities with predators. In this study, we monitored the use of 40 km of decommissioned forest roads by caribou, gray wolves (Canis lupus), black bears (Ursus americanus), and moose (Alces americanus) 1–3 years after reclamation, using 232 motion-activated camera traps. We compared four additive treatments (meaning that each successive treatment included the treatment prior): closing the road to human access, decompacting its soil, planting black spruce (Picea mariana) trees, and adding enriched soil. We assessed the influence of treatments, use by other large mammals, and characteristics of the surrounding environment on road use by the four species. Caribou used the planted treatment (which also included closing and decompacting) more than the closed-only (reference) treatment, but treatments did not influence the use of decommissioned roads by bears and moose. We could not assess the use of treated roads by wolves because of low sample size. Road use by caribou declined with local moose density, but increased with local bear density. Caribou were observed more frequently on roads surrounded by regenerating and mature coniferous stands; caribou also preferentially used roads surrounded by wetlands. Our results suggest that the treatment combining road closure, soil decompaction, and tree planting could be beneficial to caribou, highlighting the relevance of including active restoration efforts in caribou conservation programs. We recommend that such a treatment be added to road decommissioning protocols for the conservation of caribou, alongside broad-scale habitat protection.

Merging prescribed fires and timber harvests in the Sierra Nevada: Burn season and pruning influences in young mixed conifer stands

In dry, productive forests where historically infrequent high-severity fires are now common, new silvicultural systems will be needed to better align management activity with the ecosystem's dependent disturbance regime of frequent low and moderate-severity fires. Merging timber harvests with prescribed fire programs can be advantageous because each disturbance provides benefits that the other cannot provide alone. We conducted a study aimed at providing information to managers interested in merging gap-based silviculture with frequent prescribed fire. We studied the influence of burn season (spring versus fall) on canopy mortality and damage by conducting prescribed burns in 13-14 year old stands that had been regenerated with gap-based silviculture. We also pruned sugar pine (Pinus lambertiana) and incense-cedar (Calocedrus decurrens) prior to burns to evaluate the influence of pruning on fire related mortality and damage. Fall (21%) and spring (19%) burns resulted in similar amounts of mortality two years following burns, but the fall burns consumed considerably more fuel compared to spring burns. Percent volume crown scorch was greater in spring burns and greater when crown bases were low to the ground. Fall burns were generally favorable assuming a management context where fuel consumption and survival is desirable. However, either burn season may be acceptable using fire as a thinning mechanism is desired to encourage the development of low-density, mature stands. As a pre-fire treatment, pruning did not clearly reduce fire-related mortality or crown damage. Considering that pruning itself is a form of crown damage, it could be considered counterproductive as a pre-fire treatment because of increased heat entering pruned crowns as a result of increased surface fuel and the loss of heat-buffering lower branches. Merging gap-based silviculture with prescribed fires in perpetuity may be initially complex operationally in the Sierra Nevada, but it offers managers a disturbance regime-guided method for sustaining heterogeneity at fine and coarse scales while maintaining low surface fuels. The timing of introducing fires into young stands as well as traditional timber management tools such as rotation ages and harvest intervals can be altered depending on exact objectives.

Bioproductivity of the forests of the Cheremsky Nature Reserve

Climate change undermines the stability of natural ecosystems and adversely affects human life. Forest biocenoses can regulate the gas exchange of the atmosphere, accumulate and sequester carbon dioxide emissions, which are dangerous for the environment, in the phytomass components for a long time. The purpose of this study is to investigate the dynamics of bioproductivity of stands of the main forest-forming species of the Cheremsky Nature Reserve by components of phytomass and the carbon deposited in them. To solve the tasks of the study, the method of P.I. Lakyda was used. Experimental data of temporary trial plots, which fully characterize the forest massifs of the object under study, were used for modelling. The ratio coefficients Rv were calculated for stem wood (Rv(sw)); stem bark (Rv(sb)); branches (Rv(b)); leaves (needles) (Rv(l)). It was established that all above-ground components of Scots pine phytomass are described by regression equations. The coefficients of determination turned out to be insignificant, for the wood and bark of the stems of silver birch and common alder. In the structure of the phytomass of the forest stands of the reserve, the largest share (72.0%) falls on coniferous stands, a much smaller share – on soft-wood stands (26.0%) and the smallest – on hard-wood stands (2.0%). Over 13 years, the density of phytomass of stands and the carbon sequestered in it increased 1.4 times. Every year, forest biocenoses of the reserve release 6,989 tonnes of oxygen (4.2 t·ha-1) into the atmosphere. The main volume of oxygen (91.8%) is produced by coniferous stands. Based on the collected research material for stands of the main forest-forming species of the Cheremsky Nature Reserve, the following were calculated: ratios of above-ground phytomass components to their stock in the bark; mathematical models for evaluating the dynamics of phytomass components; standards for calculating oxygen productivity. The results of the study of the bio- and oxygen productivity of the forests of the Cheremsky Nature Reserve will be a significant contribution to effective management of the forest reserves, as well as to solving problems related to climate change at the regional and global levels

Importance of climate‐induced tree species composition changes in forecasting the amount of reachable habitat for forest birds

AbstractAimBird and tree species distributions will shift along with future climatic conditions through direct effects related to species responses to bioclimatic variables. In addition, tree species composition changes should indirectly drive changes in forest bird habitats. Here, we predicted the effects of climate changes on the amount of reachable habitat for forest birds and teased apart the role of the indirect effects.LocationFrance.MethodsWe projected tree and bird species distributions (2020 and 2050) using generalized additive models which accounted for climatic conditions at a large scale (France) and local environmental conditions at regional scale. The projections combined two scenarios of climate changes (RCP 2.6 and 8.5) and two scenarios of forest management (increase in either deciduous or coniferous stands). We modelled the amount of reachable habitat with landscape graphs and the equivalent connectivity index (EC) for five birds associated to the main forest types of the study area. To differentiate the sources of EC change between 2020 and 2050, we compared two future landscape graphs including only the indirect effect, or the direct and indirect effects of climate changes.ResultsFor birds with low and intermediate thermal maxima, climate‐based distributions were nearly stable over time (absence of direct effects), EC change was only attributed to indirect effects. In contrast, for bird species with high thermal maximum, EC change was mostly driven by direct effects (more favourable climatic conditions) and little by indirect effects.Main conclusionsUsing an innovative modelling framework that bind species distribution and connectivity models with climate and land use changes in forest, we showed that EC dynamics could be completely due to climate‐driven changes in tree species composition. Our results highlight the importance of accounting for the indirect effects of climate changes, especially in forests where major shifts in tree species composition are expected.

Long-term trends in forest bird populations reflect management changes in Central European forests

In areas where forest is under long-term human influence, we can expect that forest bird populations will be affected by changes in forest management. Consequences of such forest management changes can be studied using long-term population trajectories of habitat-defined groups of bird species because various species are associated to different habitat types. Here we focused on 51 species of common forest birds in Czechia, a central European country, using data from a nation-wide breeding bird monitoring scheme collected from 1982 to 2019. Important changes in forest management took place over this time period in Europe and we asked whether the trends in Czech forest bird populations reflected these changes. For this purpose, we defined nine groups according to the species’ habitat associations in respect of stand size, vegetation layers and tree species composition. We calculated annual population indices using log-linear models with Poisson distribution for every species and composed these annual indices into multispecies indicators (MSIs). MSI of all forest birds, as well as MSIs of three groups of habitat generalists showed significant increases over the focal period. The groups of more specialized species showed more variable population trajectories: birds of the shrub layer decreased, whereas birds of the forest canopy and birds of broad-leaved trees increased, and populations of birds of forest edges, forest interior and coniferous trees were stable. These patterns in forest bird populations are consistent with forest maturation and increasing wood volume that took place in Czech forests over several decades. Such changes in forest environment are likely consequences of the change in purposes of forest management from fuel wood to timber harvesting that took place in 20th century resulting in a longer rotation period. Increases in species associated with broad-leaved trees can be explained by replacement of coniferous stands by stands of broad-leaved trees indicating recovery of forest environment towards more natural conditions as majority of the forested area would be naturally covered by broad-leaved vegetation in Czechia. In addition, the occurrence of some broad-leaved trees within coniferous stands, a common practice in Czech forestry, may also provide benefits to populations of bird species associated with broad-leaved trees. Taken together, these results support suitability of current forest management for forest birds that corresponds to recent findings from several other European regions. However, we should take this conclusion with caution because the increases of generalist birds may be also driven by factors outside the forest environment.