Deadwood Volume Research Articles

Response of Bryophytes to Disturbances in Managed Forests. A Case Study from a Polish Forest

Forest management practices fundamentally impact the structure of a forest (relatively young stage of forest development, dominating stands with only one or two species of trees, planting coniferous tree species on habitats of deciduous forests, introducing alien tree species, very limited volume of dead wood). Bryophytes are especially sensitive to silvicultural practices. The aim of this study was to examine the importance of particular substrates for maintaining bryophyte species diversity in the Murckowski Forest (Silesian Upland S Poland), which is at present a managed forest. In 100 sampling plots, the structure of the forest and the species composition, frequency and abundance of bryophytes on different types of substrates (ground, tree base, tree trunk and dead wood) were analysed. In total, 54 bryophyte species were recorded (five liverworts and 49 mosses). The largest number of species was observed on dead wood (42), while the lowest number was of typical epiphytes growing on tree trunks bark more than 30 cm above the ground (18). This study confirms that dead wood is a key habitat and determines not only the number of epixylic species, but also the whole richness of bryophyte species. Maximal diameter of trees and presence of old tree stands were significant factors for species that were colonizing the tree bases.

Testing the relative sensitivity of 102 ecological variables as indicators of woodland condition in the New Forest, UK

Abstract Forests globally are facing an increasing number of threats from modified disturbance regimes, novel stressors and changing environmental conditions. This has ultimately resulted in declines in the ecological condition of many forest and woodland ecosystems, leading to widespread tree mortality and stand dieback. Effective indicators of overall woodland ecological condition are therefore needed for environmental monitoring and to support management responses. To test the effectiveness of different variables that could potentially be used as indicators of woodland condition, 102 variables that describe woodland structure, composition, functioning, edaphic conditions and disturbance regimes were assessed along 12 replicate gradients of beech stand dieback. Results indicated that 35 variables differed significantly between at least two stages of the dieback gradient, indicating their sensitivity to stand dieback. Seven of these indicators related to woodland species composition, two to functional processes, 20 to structural features, four to edaphic conditions, and two to disturbance regimes. These results demonstrate that effective indicators can potentially be identified for each of the ecological categories. Effective composition indicators included species richness of ectomycorrhizal fungi, ground flora and epiphytic lichens; functional indicators were soil respiration rate and net nitrification rate; edaphic conditions included soil Na:Ca ratio, exchangeable sodium, total carbon, Ca:Al ratio; structural indicators included canopy openness, litter cover, sward height, and volume of deadwood, and for disturbance the indicator was Equus dung density. Other measures, such as shrub cover and species richness of carabid beetles and spiders, were not found to vary significantly along the dieback gradients, and were therefore not identified as effective indicators. These results demonstrate the value of gradient analysis for evaluating indicators of woodland condition, but also highlight the need for multi-site studies to identify indicators with widescale applicability.

The effect of spruce plantation density on resilience of mixed forests in the Perm Krai

Over the course of the last few decades, many countries across the globe have experienced mass desiccation of spruce plantations. The subject of our research was the spruce forests of the Russian Perm Krai’s mixed forest zone. Spruce is a shade–tolerant tree species and low plantation density may adversely affect the spruce health. The aim of this research is to establish how influential the spruce stand density is on causing desiccation in mixed zones in the Perm Krai. The results of an on-site survey which had recorded spruce desiccation in 2017 were analysed. Within the boundaries of the aforementioned forest areas, 2017 saw the desiccation of spruce trees in 301 forest allotments covering an area of 5,343.7 ha. The value of the weighted average category of spruce forest health in Prikamye varies from 2.7 (severely weakened) to 4.2 (desiccating), and the percentage of the volume of spruce deadwood varies from 17% to 59.5%. When the spruce stand density rises from 0.4 to 0.8, spruce stand resilience to desiccation increases.

A dataset of forest volume deadwood estimates for Europe

ICP-Forests relies on a representative pan-European network based on a 16 × 16 km grid-net covering around 6,000 plots. Dead wood volumes for 3,243 plots, related to 19 European Countries, are presented in this data paper as a result of harmonised sampling procedure, and under compliance with FAIR Data Principles. Dataset access is at . Associated metadata are available at .

A plot-level exploratory analysis of European forest based on the results from the BioSoil Forest Biodiversity project

The lack of multi-dimensional data is one of the major gaps which limit the knowledge and the assessment possibilities of European forests. Nowadays, the most extensive and complete data on the European forest statuses are given by National Forest Inventories (NFIs) which provide information about the extent of forest’s resources and their composition and structure. Traditionally, NFIs collect data related to trees, with a limited consideration of other habitat components, such as ground vegetation. This information which goes beyond the mere arboreal component is instead essential for a more complete forest biodiversity assessment. This paper is aimed at introducing the ICP Forests LI-BioDiv database which resulted from BioSoil Forest Biodiversity, a large collaborative European project. This database is organized as a multi-dimensional forest geodatabase that contains forest structure and vegetation records collected in 19 European countries in the period of 2005–2008. The data were acquired from 3311 geocoded plots where several different types of data were gathered: stand-level general information, tree-level data, deadwood, canopy closure and floristic composition. This paper is structured in order to: (1) give a clear overview of the raw data available in the database and to (2) present an elaboration of raw data to calculate simple plot-level forest variables (biomass, deadwood volume, alpha diversity). On the basis of the results we achieved, the LI-BioDiv database appears useful mainly for research purposes aimed at studying cross-relationships between multiple forest variables and not for an operative use for monitoring and assessing European forest. In particular, we hope that this contribution can stimulate scientists to carry out cross-analysis of the database for defining future forest biodiversity indicators that could be introduced into the field protocols of the NFIs in Europe.

Short-term effects of selection, gap, patch and clear cutting on the beetle fauna in boreal spruce-dominated forests

Even-aged management based on clear cutting has simplified the structure of boreal forests, which has adversely affected ecosystem services, including biodiversity. A potential way of combining economic, ecological and social sustainability in forest management is emulation of natural disturbance dynamics. However, ecological effects of alternative cutting methods have been little studied in northern Europe. We studied the responses of beetles (Coleoptera) to four cutting treatments – selection, gap, patch and clear cutting – compared to uncut control stands. We collected beetles one year before, and one and three years after cutting using flight-intercept window traps to assess the effects of treatment, proportion of removed trees, size of harvested gaps, and the volume of dead wood on the species richness and composition of beetles. The total number of species increased sharply in the first year after cutting in all the four treatments. Three years after cutting, the difference in species richness between controls and treatments had decreased. Both species richness and community structure formed a continuum according to treatment intensity. Selection cuts were most similar to the controls, while clear cuts differed from all the other treatments. Irrespective of the treatment, species richness of saproxylic beetles increased with the volume of dead wood, while the number of non-saproxylic species increased with gap size. Contrary to expectation, the proportion of species that were found both before and after cutting did not differ significantly between the treatments. According to an indicator species analysis, two species were associated with controls, 11 with a combination of controls and selection, gap or patch cuts, 17 with patch and clear cuts, and 38 with clear cuts. Our findings suggest that increasing harvesting intensity rapidly increases the total species richness of beetles in the studied spruce forests, but that community recovery may be faster in the less intensive treatments. In the short term, most beetle species inhabiting mature managed forests seem to tolerate cutting disturbances creating open conditions. Clear cuts hosted a large number of species, including species of conservation concern, which were missing from other cutting treatments. Even a moderate increase in the level of dead wood in managed forests is likely to enhance saproxylic diversity. If the aim of management is to preserve mature-forest beetle communities, selection or gap cutting should be used instead of clear cutting.

Consequences for bird diversity from a decrease in a foundation species\u2014replacing Scots pine stands with Norway spruce in southern Sweden

Forest ecosystems are often defined by their dominant foundation tree species, which dictate forest structure and ecosystem processes. In southern Sweden, concerns are being raised because production stands of a foundation tree species, Scots pine (Pinus sylvestris), are being converted to Norway spruce (Picea abies) stands. Such conversions may lead to biodiversity loss, though the specific nature and extent of such losses remain unknown. Here, we assess the potential biodiversity impacts by contrasting the bird communities of 55- and 80-year-old Scots pine and Norway spruce production stands. We also determine the extent to which these production stands capture the available species pool by surveying conifer-dominated reserves. Our results indicate that Scots pine and Norway spruce production forests support overlapping but nevertheless distinct bird communities, though only few recordings were made of the species unique to either stand type. Among the production stands, the 80-year spruce stands had the highest average bird species richness, and largest total number of species recorded. We suggest that the higher diversity can be explained by a higher proportion of broadleaves and higher volumes of dead wood. Although the bird diversity found in the reserves was lower than expected, they benefit gamma diversity at landscape scales as they collectively supported a higher diversity of bird species than the production forests. In summary, the conversion of Scots pine to Norway spruce is likely to increase the homogeneity of the bird communities in this region.

Detecting and characterizing downed dead wood using terrestrial laser scanning

Dead wood is a key forest structural component for maintaining biodiversity and storing carbon. Despite its important role in a forest ecosystem, quantifying dead wood alongside standing trees has often neglected when investigating the feasibility of terrestrial laser scanning (TLS) in forest inventories. The objective of this study was therefore to develop an automatic method for detecting and characterizing downed dead wood with a diameter exceeding 5 cm using multi-scan TLS data. The developed four-stage algorithm included (1) RANSAC-cylinder filtering, (2) point cloud rasterization, (3) raster image segmentation, and (4) dead wood trunk positioning. For each detected trunk, geometry-related quality attributes such as dimensions and volume were automatically determined from the point cloud. For method development and validation, reference data were collected from 20 sample plots representing diverse southern boreal forest conditions. Using the developed method, the downed dead wood trunks were detected with an overall completeness of 33% and correctness of 76%. Up to 92% of the downed dead wood volume were detected at plot level with mean value of 68%. We were able to improve the detection accuracy of individual trunks with visual interpretation of the point cloud, in which case the overall completeness was increased to 72% with mean proportion of detected dead wood volume of 83%. Downed dead wood volume was automatically estimated with an RMSE of 15.0 m3/ha (59.3%), which was reduced to 6.4 m3/ha (25.3%) as visual interpretation was utilized to aid the trunk detection. The reliability of TLS-based dead wood mapping was found to increase as the dimensions of dead wood trunks increased. Dense vegetation caused occlusion and reduced the trunk detection accuracy. Therefore, when collecting the data, attention must be paid to the point cloud quality. Nevertheless, the results of this study strengthen the feasibility of TLS-based approaches in mapping biodiversity indicators by demonstrating an improved performance in quantifying ecologically most valuable downed dead wood in diverse forest conditions.

Application of next-generation sequencing technologies to conservation of wood-inhabiting fungi.

Next-generation sequencing (NGS) has significantly increased knowledge of microbial communities and their distribution. However, it is still not common to apply NGS technology to microbial conservation. We sought to use NGS technologies to evaluate conservation strategies for wood-inhabiting fungi. Evaluating a deadwood experiment 3 years after it was established, we specifically examined which tree species combinations promoted the highest richness of wood-inhabiting fungi. Deadwood enrichment was an effective strategy and logs of 6 tree species, either those with the highest wood-inhabiting fungal α and γ diversity or those with the highest β diversity, maintained >1,000 operational taxonomic units (OTUs) spread over a wide range of taxonomic groups. In comparison, a conservation strategy based only on the results of sporocarp surveys yielded 591 OTUs. This result highlights the need to use NGS approaches to inform microbial conservation strategies. We also determined that 5 tree species with the highest saproxylic beetle γ diversity simultaneously conserved wood-inhabiting fungi. Apart from deadwood volume, we suggest data on deadwood quality and species also be included as indicators, especially for wood-inhabiting fungal diversity, and incorporated quickly in forest assessment and monitoring systems in Central Europe.

Post-harvesting dynamics of the deadwood profile: the case of lowland beech-oak coppice-with-standards set-aside stands in France

In most European temperate forests, the heavy harvesting of low-quality wood for energy, a low minimum harvest diameter and a short rotation period, result in the limited deadwood resources. However, areas are being set aside in managed forests to restore deadwood levels. Coppice-with-standards is a silvicultural method characterized by periodic logging which clear-cuts coppice trees and removes some standard trees. We studied the deadwood profile (i.e., both amount and diversity) in oak-beech coppice-with-standards over time-since-the-last-harvest in order to evaluate how long it takes to recover significantly high amounts and diversity of deadwood substrates. A total of 282 circular 500-m2 plots were set up in 24 forests in southwestern France. We sampled five time-since-harvest classes within 80 years of the time elapsed since the last harvest. At the plot level, we used Generalized Linear Mixed Models to compare both deadwood volume and diversity among time classes. Diversity was also compared within time classes through accumulation curves. Deadwood legacies were very scarce after harvesting, both for volume and diversity. It took more than 70 years for deadwood amounts to become significantly higher than just after harvest; deadwood diversity was significantly higher only 30–50 years after harvesting due to quick snag recruitment. Crown deadwood, a particularly specialized resource rarely recorded, provided roughly 10–20% of the total deadwood amount throughout the study period and should be systematically recorded in further studies. Time-since-the-last-harvest was the best explanatory variable for both deadwood volume and diversity. We therefore recommend installing permanent set-aside areas to ensure deadwood conservation.

Non-lethal monitoring of longicorn beetle communities using generic pheromone lures and occupancy models

Longicorn beetles are a diverse group of insects that perform critical ecosystem services and are indicators of forest health. Most longicorn species are data deficient, and many are considered at risk. Longicorn beetle monitoring often relies on lethal methods and are time and cost intensive. In this study we investigated the use of generic pheromones in conjunction with species- and Bayesian community-level hierarchical modeling that accounts for imperfect detection, as a rapid tool for monitoring longicorn beetle diversity. Using 50 flight-intercept traps deployed for one month at two sites in a traditionally-maintained landscape in SW Romania, we implemented non-lethal surveys to evaluate the longicorn species abundance and estimate beetle occupancy. We captured and identified 2370 longicorn beetles of 28 species; two species, Phymatodes testaceus and Plagionotus detritus accounted for more than ½ of the captures, and nine species were only captured once. However the most abundant species estimated in our area was Mesosa nebulosa (36–60 individuals per trap location). Using co-occurrence of high and low detection species, as well as habitat associations, we estimated that 39 species (30–57 95% posterior interval) were present at any given site, suggesting that our survey did not capture the full longicorn diversity. Beetle diversity, occurrence and abundance were associated with higher tree density, volume of dead wood and number of stumps, and lower canopy cover. Our methods allowed to discriminate between common species with low detection, and rare species, and are a promising tool for the rapid assessment of longicorn beetle diversity, as well as the conservation status of listed and non-listed species.

Does dead wood volume affect saproxylic beetles in montane beech-fir forests of Central Europe?

As most European forests are commercially managed for wood production, excluding the disintegration phase of the forest development cycle, a serious decline of numerous species has been observed. The intensity of forest management is critical for biodiversity conservation, especially in regard to saproxylic organisms, as it reduces the abundance of old trees and dead wood. We studied saproxylic beetles in 12 montane beech-fir stands in a Central European mountain range. We used 72 flight interception traps exposed for two vegetation seasons (2012 and 2013) placed at sites characterized by three levels of dead wood volume. In total, 7990 individuals of 287 species belonging to 41 families were collected. Species richness and abundance of both non-threatened and threatened species showed no significant differences among the three studied forest stand categories. Nevertheless, the presence of both non-threatened and threatened species in the studied forest stands was affected by several environmental variables. Large diameter dead wood, dead wood in the last decay stage and dead beech wood close to the traps significantly affected the assemblage of threatened beetles. Canopy openness, thin dead wood in the wider trap surroundings and dead wood in the second and third decay stage in the closer trap surroundings affected the assemblage of non-threatened species.

The devil is in the detail: Metabarcoding of arthropods provides a sensitive measure of biodiversity response to forest stand composition compared with surrogate measures of biodiversity

Gauging trends in forest biodiversity and relating these to forest management practice and environmental change requires effective monitoring and assessment of spatio-temporal trends in forest biodiversity. Taxa- and habitat-based surrogate measures of biodiversity, or ‘biodiversity indicators’, are commonly used to convey information about the state of the biological community since they can be assessed relatively quickly and cheaply by non-experts. Direct measures of a component of biodiversity are also increasingly feasible using DNA metabarcoding; ‘Next Generation Sequencing’ has facilitated the rapid characterisation of combined multiple species samples by sequencing their DNA barcodes in parallel, simultaneously reducing the need for taxonomic expertise and the time and cost required to obtain biodiversity data across a wide range of taxonomic groups.We investigated whether biodiversity information obtained from DNA metabarcoding of mass-trapped arthropods and from a range of taxa-based surrogate measures of biodiversity (e.g. carabid beetles, vascular plants) provide: 1) similar estimates of alpha and beta diversity and 2) provide similar forest management related conclusions. We also explored how well habitat-based surrogate measures of biodiversity (e.g. stand structure, volume of deadwood) predict observed biodiversity patterns. The study was conducted in Thetford Forest, UK within 15 forest plantation stands (5 Scots pine-oak mixtures, 4 Scots pine and 6 oak monocultures).Our results demonstrated a high level of congruence between the metabarcoding and taxa-based surrogate measures of biodiversity. The wider range of taxonomic groups identified using a metabarcoding approach offered the potential to identify taxa sensitive to the environmental variable that was being manipulated experimentally (i.e. the composition of forest stands). Most habitat-based measures of biodiversity failed to predict species assemblage differences between stands.

Sampling system for estimating woody debris in an urban mixed tropical forest.

Woody debris, defined as standing and downed deadwood, consists in an essential component of the forest carbon stock. However, few studies have been carried out to get an efficient and accurate sampling procedure for estimating it. This work proposes two methodologies to estimate the woody debris volume in a Brazilian mixed tropical forest: 1) two-stage systematic sampling, using a mixed methodology, in which the Strand's method is applied to standing dead trees and stumps, and line intercept sampling is used to fallen trees and branches; and 2) ratio estimate of the sum of cross-sectional areas of deadwood pieces and forest basal area, aiming to obtain the total woody debris volume indirectly in the natural forest. Conversions for biomass and carbon stocks were made applying the mean basic density on the estimates of deadwood volumes. Both methodologies are accurate for woody debris volume estimates, with a sampling error equal to 16.1% (methodology 1) and 5.7% (methodology 2), at a 95% probability level. Thus, the methodology 2 has potential to be used in strategic forest inventories of woody debris, such as in National Forest Inventories, due to increasing importance of its quantification in all forest ecosystems.

Characterising the richness and diversity of forest bird species using National Forest Inventory data in Germany

Data collected by forest inventories like the third National Forest Inventory (NFI-3, 2011–2012) in Germany was proposed to monitor forest biodiversity and evaluate existing forest management practices on a national scale. A data set was created from the NFI-3 data for analysis purposes which contained variables relevant to the habitat requirements of native forest bird species. Information on the distribution and abundance of 20 native forest bird species was taken from the Atlas of German Breeding Birds (2005–2009, 3003 grid cells). They form two important ecological groups: cavity-nesting and deciduous forest birds. For the first time, this data was combined with NFI-3 data and analysed using Random Forest models and partial dependence plots to determine which forest variables recorded by the NFI-3 were most closely related to forest bird species richness and diversity in temperate forests.It was shown that changes in forest bird species diversity and richness correlate with the NFI data but the different sampling methods of the NFI and bird species data also created methodological challenges which are discussed. The most important drivers of the richness and diversity of deciduous forest and cavity-nesting bird species are forest stand age and forest ownership. Deciduous forest and cavity-nesting birds show a preference for the way state, federal and municipal forests are managed over private forests. Private forests have significantly lower deadwood volumes and high proportions of coniferous trees, both of which are forest characteristics that lower the richness and diversity of bird species. Our findings show that efforts to protect forest birds should target managed forests older than 100 and 200 years and forests with total deadwood volumes >46.3 m3/ha. Protected areas also exhibited higher diversity and richness of forest birds which highlight their importance as suitable target areas for the protection of forest birds.

Вплив природних факторів на динаміку букового (fagus sylvatica L.) пралісу Українських карпат

Міжнародні дослідження 15-річної динаміки букового пралісу проведено на 10-гектарному стаціонарному дослідному об'єкті в Угольському масиві Карпатського біосферного заповідника. Проаналізовано вплив вітровалу 2007 р. та потепління клімату на структурні елементи екосистеми пралісу. Виявлено достовірні зміни окремих показників пралісу внаслідок сильного впливу вітру: найбільші коливання характерні для густоти дерев – після втрати 10 % (у 2007 р.) вже в 2010 р. густота збільшилася на 6, а в 2015 р. – на 59 %; істотно зріс і запас мертвої деревини (відповідно на 41 та 6 %); відносне зменшення найбільшим було для кількості підросту (на 19 та 14 %); зменшення запасу деревини було вже меншим (на 7 і 4 %); зменшення суми площ поперечного перетину було неістотним (на 4 і 2 %). Аналіз реакції букового пралісу на сильний вплив вітру підтверджує гіпотезу про максимальну стійкість таких лісових екосистем до стихійних явищ, а ідентифіковані кількісні зміни дали змогу розробити принципову схему сильного впливу вітру на праліс. Дискусійним залишається питання збільшення приросту за діаметром під впливом потепління клімату – у 2010 і в 2015 рр. воно було достовірним для більшості ступенів товщини, але на його динаміку вплинув також і вітровал через зрідження намету.

Impact of the European Beaver Castor fiber on Deadwood Resources in Lowland River Valley – A Case Study in Wigry National Park (NE Poland)

The impact of the European beaver Castor fiber on deadwood resources near dams on the rivers of Wigry National Park (northeastern Poland) has been analyzed. The river sampling area was subdivided into the flooded zone, scarp and upland.We found that beaver feeding was limited to the flooded zone and the scarp. Within a distance of 40 m of the river, beavers browsed 75% of all deadwood pieces (wood debris, stumps, dead trees). The wood generated via direct browsing by beavers made up 5% (3.29 m3/ha) of the total wood volume and 35% (641 pieces/ha) of the total number of wood pieces in this region. The beavers mostly left small pieces of wood (with a mean diameter of about 4 cm) at an area after feeding. The deadwood volume and number of pieces were significantly different in front and behind the dam only in the flooded zone. The volume of deadwood in front of the dam in the flooded zone was higher by 65% than behind the dam (102 and 62 m3/ha, respectively), and the number of pieces was higher by 75% (2200 and 1200 pieces/ha, respectively).We prove that beavers generate the majority of dead wood indirectly – by flooding a part of the area. This results leads to conclusion that frequent flooding of a given area may lead to limiting the source of deadwood in the long term. We also confirm that through direct browsing, beavers produce small amounts of thin dead wood with less usefulness for other groups of animals, thus in this way beavers are not able to provide high-quality deadwood resources.

Simulating Long-Term Effects of Bioenergy Extraction on Dead Wood Availability at a Landscape Scale in Sweden

Wood bioenergy may decrease the reliance on fossil carbon and mitigate anticipated increases in temperature. However, increased use of wood bioenergy may have large impacts on forest biodiversity primarily through the loss of dead wood habitats. We evaluated both the large-scale and long-term effects of different bioenergy extraction scenarios on the availability of dead wood and the suitability of the resulting habitat for saproxylic species, using a spatially explicit forest landscape simulation framework applied in the Swedish boreal forest. We demonstrate that bioenergy extraction scenarios, differing in the level of removal of biomass, can have significant effects on dead wood volumes. Although all of the scenarios led to decreasing levels of dead wood, the scenario aimed at species conservation led to highest volumes of dead wood (about 10 m3 ha−1) and highest connectivity of dead wood patches (mean proximity index of 78), whilst the scenario aimed at reaching zero fossil fuel targets led to the lowest levels (about 8 m3 ha−1) and least connectivity (mean proximity index of 7). Our simulations stress that further exploitation of dead wood from sites where volumes are already below suggested habitat thresholds for saproxylic species will very likely have further negative effects on dead wood dependent species.

Structural Diversity in a Mixed Spruce-Fir-Beech Old-Growth Forest Remnant of the Western Carpathians

Old-growth forests are a unique source of information for close-to-nature silviculture. In the National Nature Reserve Dobročský prales (Slovakia), a remnant of mixed old-growth forests of the Western Carpathians, we analyzed changes in tree species composition, stand structure, and creation and closure of canopy gaps. The results were based on data from forest inventories of an entire reserve conducted in 1978 and 2015, extended by detailed measurements in a research plot of 250 × 250 m. We observed the expansion of common beech (Fagus sylvatica L.) at the expense of conifers (Abies alba Mill., Picea abies L. Karst.) in all layers of the stand. Due to a lack of conifers in the category of saplings >130 cm and an abundance of coniferous deadwood, we hypothesize that this development will lead to the dominance of beech. All development stages revealed a reverse J-shaped diameter structure; however, they differed in the majority of basic stand characteristics (e.g., growing stock, basal area, tree density, deadwood volume). Most of the structural indices did not differ between development stages, confirming a relatively high degree of structural differentiation throughout the development cycle. The total gap area reached 18%, with the dominance of small gaps ≤100 m2. Nevertheless, only canopy gaps >100 m2 formed by the mortality of three or more trees were of higher importance for the extensive establishment of natural regeneration.

Substrate specific restoration promotes saproxylic beetle diversity in boreal forest set-asides

In many parts of the boreal biome intensive forest management has resulted in profound changes in forest structure, tree species composition and dead wood availability, and by so negatively effecting forest biodiversity. Restoration of degraded forest habitats is therefore of high priority, both internationally and nationally. Consequently, it is of uttermost importance to develop cost-efficient restoration methods. We have therefore initiated a cost neutral ecological restoration experiment aimed at increasing the variety and volume of dead wood in voluntary set-asides (as part of the FSC certification requirements) by mimicking the two natural disturbances, forest fire and small scale gap dynamics. We studied how tree species and substrate type, i.e. the way in which a tree was killed (cut, girdled, tipped over or cut to produce a high stump), affect species composition, abundance and species richness of saproxylic beetles. We found that species composition differed between tree species in burned as well as gap-cut stands, and that tree posture, i.e. standing or downed trees, also affected species composition in gap-cut stands. In addition, abundance and species richness differed between tree species in gap-cut stands, generally being higher in spruce than in pine and birch. Based on our results we recommend a wider practice of dead wood creation involving a multitude of tree species and tree postures, through mimicking natural disturbances in the management of boreal forests. Furthermore, we suggest that voluntary set-asides provide an excellent opportunity for restoration as they are wide spread and already available in the forest landscape. Restoration cost can therefore be kept at a minimum or totally avoided as in this study.