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Highlights • Three-toed woodpecker and Siberian jay are important biodiversity indicators. • Prescribed burning changed indicator values of biodiversity indicators. • Biodiversity indicators indicate high species richness and structural complexity. • We must be careful with using previous identified indicator species in ecosystems subjected to ecological restoration. Abstract A wide range of different biodiversity indicators have been identified in different biomes and types of environments. However, we currently lack a clear understanding under which circumstances proposed biodiversity indicators are valid indicators and when they are not. Here we conducted a large-scale restoration experiment by emulating natural disturbances through prescribed burning and gap-cutting. From this experiment data of resident forest birds was used to, (1) identify biodiversity indicators in the middle and northern boreal zone, (2) test the effect of forest restoration practices on biodiversity indicators and (3) explore the patterns when biodiversity indicator analyses are performed across a wider range of forest types including both restored and unrestored sites. Additionally, to understand the occurrence of species we correlated their occurrence with local habitat structures across different forest types. We found that both the three-toed woodpecker (Picoides tridactylus) and Siberian jay (Perisoreus infaustus) were important biodiversity indicators for the middle/northern boreal zone. The occurrence of these species can generally be used to identify species rich areas across different forest types. However, the three-toed woodpecker, the best indicator for unrestored forest, lost its indicator value after prescribed burning; in these stands the goldcrest (Regulus regulus) was the best biodiversity indicator. Based on habitat associations, we suggest that biodiversity indicators in boreal forest not only indicate high species richness but also structural habitat complexity. Our results draw attention to the fact that one must be careful about using previously identified biodiversity indicators in ecosystems subjected to ecological restoration. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

• Continuous Cover Forestry is highly debated. • We reviewed long-term yield and biodiversity between two silviculture systems. • Comparative studies between silviculture systems are inconclusive. • Species sensitive to clearcutting may benefit from Continuous Cover Forestry. • More long-term experiments are needed, especially on conservation species. There is an increasing interest in implementing Continuous Cover Forestry (CCF) as a tool to mitigate negative effects of the traditional rotation forestry system on biodiversity. However, the effects of CCF on forest growth and yield and on biodiversity is still poorly known. In this qualitative review, we compare biodiversity and long-term yield between the selection system, which is a type of CCF practiced in full-storied forests, and the traditional rotation forestry system. We specifically focus on forests dominated by Picea abies , which is a tree species of high economic relevance. Our literature search resulted in 17 publications on stand growth and yield and 21 publications on biodiversity. A majority of simulation studies found a higher long-term yield in the rotation forestry system, but it is challenging to conclude which system is the most productive. The magnitude of the difference in yield between systems, and how it varies across different environmental conditions, remains to be determined. For biodiversity, comparisons of species assemblage and individual species were only made to certain phases of the rotation cycle (recent clearcuts and middle-aged stands). Nevertheless, two aspects can be highlighted: i) the species assemblage in clearcuts differ substantially from stands managed with the selection system. Some of these effects may however be short lasting as examplified by studies on beetle assamblages showing that middle-aged rotation forestry stands become more similar to stands managed with the selection system, ii) the selection system maintains a similar species assemblage as the uncut control during the first years after cutting. In conclusion, management with the selection system may come with a loss in long-term stand yield, but much of the species assemblage is maintained after logging. We recommend future studies to specifically focus on long-term effects on biodiversity – in particular on species of conservation concern. There is also a need to establish a long-term research infrastructure to further develop the field. [ABSTRACT FROM AUTHOR]

Large scale use of even-aged silviculture (clear-cutting) commencing in the mid-20th century has had negative impacts on forest biodiversity. As a consequence, uneven-aged silviculture is currently being considered to help meet the ecological and social criteria required for sustainable forest management. Uneven-aged silviculture (e.g. selective felling) involves selective removal of some older trees in a stand which may to some extent mimics natural small scale stand dynamics and thus potentially benefit species associated with old forests. Here we test whether selective felling benefits beetle biodiversity by producing beetle assemblages that better resemble those of old growth stands than those found in uncut production stands. We conducted a field study in northern Sweden, comparing beetles assemblages collected with window traps in three spruce dominated stand types: (1) Stands recently (on average 7 years prior to the study) subjected to selective felling ( Selective felling ), (2) mature uneven-aged stands without recent history of management, resembling selective felling stands prior to management ( Uncut ), and (3) old-growth stands with high conservation values ( Old growth ). As predicted, we found that assemblage composition was similar in selective felling and old growth stands, and that assemblages of cambivores and obligate saproxylics (marginally significant) differed between these two stand types and uncut stands. The differences were largely explained by a higher abundance of saproxylic species presumably associated with old growth conditions and large volumes of deadwood. Thus, although overall assemblage composition did not differ between stand types, part of the beetle community seemingly benefited from selective felling. We therefore recommend that selective felling is considered as an alternative to clear-felling to maintain biodiversity values. [ABSTRACT FROM AUTHOR]

Decline in biodiversity have increased the interest in alternative forest management approaches. Uneven-aged silviculture has been proposed as a mean to maintain continuity of forest canopy cover, mimic small-scale disturbances and provide a stratified forest structure similar to that of old-growth forests and therefore better maintain species associated with unmanaged forest. We used a large-scale chronosequence study spanning 50 years to study beetle diversity in uneven-aged silviculture compared with both short-term impacts and the longer-term legacy of even-aged silviculture. We compared: (1) even-aged recently clear-felled stand, (2) even-aged recently thinned stand, (3) uneven-aged stands subjected to selective felling with (4) uneven-aged reference stands to evaluate whether abundance, species richness and composition of beetles (Coleoptera) were affected differently by even-aged than by uneven-aged management. We collected 15,147 beetles from 461 species using flight interception traps in 30 stands. Beetle composition was maintained in uneven-aged managed stands; composition did not differ from unmanaged reference stands, the exception being cambium consumers. Both even-aged silviculture treatments (clear-felling and thinning) had different beetle composition compared to the reference stands, indicating that assemblages had yet to recover even 50 years into the rotation. However, beetle composition did not differ between uneven-aged managed and thinned stands. The result supports our prediction that uneven-aged silviculture better maintains beetles assemblages associated with semi-natural mature forest than even-aged silviculture. The greater temporal continuity in selectively felled stands could benefit species dependent of mature or old growth forest since some of the needed habitat qualities are continuously available. Uneven-aged silviculture could therefore serve as an important tool for landscape planning to benefit biodiversity and thus help fulfil environmental commitments. However, uneven-aged silviculture may still alter the forest and should therefore be viewed as an alternative to even-aged silviculture, rather than to set-asides. [ABSTRACT FROM AUTHOR]

Stumps comprise up to 80% of the residual deadwood following clear cutting and are a significant source of biomass for bioenergetic applications. However, stump harvesting may pose significant conservation risks for saproxylic organisms that occur in residual deadwood. To define retention targets for stump harvesting operations, we compared abundance and species richness of saproxylic beetles within individual stumps as well as species accumulation curves in replicated pairs of clear cuts with and without stump harvesting in northern Sweden. Using 20 stands, we sampled 1049 stumps using eclector traps and collected 9821 beetles representing 253 species with known saproxylic biology. Nineteen of these species were red-listed in Sweden. We hypothesized that individual stumps left following stump harvesting would contain higher densities and species richness than in clear cuts without stump removal due to crowding of beetles into increasingly limited habitats. However, we found no difference in density or richness within individual stumps between control clear cuts and stumped stands. We also compared species richness between control and stumped treatments using rarefaction within individual stands and across all stands and found no difference. As with density and richness, beetle composition at the stand-level did not differ between control and stumped stands. Thus, the density of surrounding stumps within a stand had very little effect on beetle assemblages in residual stumps. We estimated the effect of stump harvest on species richness at the stand level by combining all samples and extrapolating a rarefaction curve derived from the landscape-level species pool to an accumulated sample volume of 48 m 3 which corresponds to the total volume of stumps on average-sized clear cuts in Northern Sweden. Using this curve, we compared differences in species richness in average-sized clear cuts with 100% (48 m 3 ) and 25% (12 m 3 ) stump retention and found that stump harvest resulted in a 26% (95% C.I. 7–41%) loss of species. While the absolute scaling of the landscape-derived rarefaction does not reflect species loss at the stand-level because the combined curve reflects all rare species in the landscape, the relative species loss derived from this curve may serve as credible benchmark for species loss at the stand level following current stump harvesting practices. This benchmark may be further calibrated with additional information on number of singleton species and estimates of maximum species richness. [ABSTRACT FROM AUTHOR]

Management of boreal forests for timber production has caused changes in forest structures and disturbance regimes, which have influenced a wide range of organisms. The aim of this study was to evaluate how composition of epigaeic (ground-living) beetle assemblages is influenced by stand age and management history in a heavily managed boreal forest landscape. We compared the epigaeic assemblages among stands of three ages: (1) young (8–25 years) and (2) middle-aged (40–58 years) stands regrown after clear-cutting, and mature stands (80–130 years) that had been selectively cut historically but never clear felled. We sampled epigaeic beetles in each of 42 stands, using 10 pitfall traps during seven summer weeks. More than 9000 specimens were collected and identified. The assemblages in young stands differed from those in middle-aged and mature stands, both for the Staphylinidae (rove beetles) and all beetle families combined. Carabidae (ground beetles) composition differed between young and middle aged stands only, and assemblages of Curculionidae (weevils, bark beetles and allies) differed between young and mature stands only. Assemblages of Leiodidae (round fungus beetles) had similar composition in all three stand types. Considering all families, young stands generally harbored fewer species and lower abundances compared with middle aged and mature stands. However, the Leiodidae had similar species richness in all three stand types. The lack of differences in assemblage composition, species richness and abundance between middle aged and mature stands suggests that epigaeic beetle assemblages recolonize following clear-felling. However, our collections included large numbers of unique and usually rare species in mature stands, indicating that old forest is important for the conservation of epigaeic beetles. Furthermore, the lower abundance of these beetles in young stands indicates that an increasing proportion of young stands on managed landscapes will reduce the overall abundances of epigaeic beetle species, with potentially negative impacts on recolonization. [ABSTRACT FROM AUTHOR]

Abstract: The aim of this study was to evaluate how future harvesting of spruce low stumps as a renewable energy source, might influence the saproxylic (wood living) beetle fauna. Species richness, abundance and assemblages of saproxylic beetles were compared on low stumps, high stumps and logs of spruce on 10 clear-cuts in northern Sweden. The sampling was conducted with emergence traps and a total of 929 individuals and 120 species were collected. No significant differences in beetle abundance or species richness were detected between substrate types. However, there were clear differences in assemblage composition between all substrate types. Our results suggest that low stumps created at final felling support as many species and individuals per volume dead wood as other dead wood substrates and that they are therefore overlooked as substrates for wood living organisms. Consequently, harvesting of low stumps might have negative effects on the diversity of saproxylic beetles, as up to 80% of the dead wood remaining on clear-cuts is in the form of low stumps. Future studies should evaluate if compensatory measures can be performed to minimize negative impacts. [ABSTRACT FROM AUTHOR]

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• Boreal forest clear-cutting change species composition of mosses and liverworts. • After half a century both cover and occupancy are changed in 1-ha secondary stands. • Species thriving in shade and on living or dead trees are still fewer. • Current habitat factors explain much of the remaining differences. • Species losses can be mitigated by providing shade and tree substrates. A growing proportion of the boreal biome consists of managed even-aged secondary forest stands regenerated after clear-cutting. Many disturbance-intolerant species may not be able to recolonize or reach their original abundance in these stands before the next clear-cutting, potentially causing large-scale biodiversity losses. Boreal bryophytes (mosses and liverworts) include many species intolerant to clear-cutting, and at small spatial scales species richness and occupancy has been shown to remain changed in secondary stands half a century after logging. To assess if such persistent changes occur also at the stand scale, we listed and estimated cover of all bryophyte species in 1-ha plots, comparing 14 secondary stands originating from clear-cutting 40–60 years earlier with 14 older semi-natural stands. The large plots also made it possible to assess differences in occupancy and abundance for more bryophyte species than in previous studies. Species composition differed significantly for both mosses and liverworts, but unlike earlier studies, we could not detect any significant difference between stand types in species numbers. Thirteen species were significantly associated with semi-natural stands and the total cover of liverworts was less than half in secondary stands. Secondary stands had significantly fewer species typically occurring under shady conditions and/or mostly growing on "tree substrates" (dead wood and/or bases and stems of living trees). Ordination analysis further emphasized the importance of shade and suitable deadwood substrates; the among-plot variation in bryophyte species composition was related to amount of coarse deadwood as well as to gradients from shady spruce dominated to open pine dominated stands and from polar- to equator-facing slopes. Besides lack of suitable habitat conditions in secondary stands, dispersal limitation may have caused a colonization time lag for some species. The clear importance of stand scale habitat conditions for bryophyte species composition calls for management adaptions to facilitate life boating and/or recolonization by ensuring availability of shade, coarse decomposing logs, and specific deciduous tree species (Populus , Salix , Sorbus) in secondary stands. [ABSTRACT FROM AUTHOR]

• Burning increased species richness of beetles compared to gap-cut and reference stands. • Species composition differed significantly between all three groups of stands. • Most species benefitting from burning are fire dependent/favored species. • Gap cutting maintained pre-treatment beetle assemblages but benefitted e.g., cambivores. • Both restoration methods are complementary to e.g., free development set-asides. Accelerating declines in biodiversity worldwide have accentuated the need for conservation actions. Unfortunately, the decline is unlikely to be reversed by traditional conservation alone, e.g., green tree retention at clear-felling and setting aside protected areas for free development. Instead the practice of ecological restoration has come to play an ever increasing role. Using a before-after control-impact experiment in boreal forest voluntary set-asides, we evaluated the usefulness of two methods of ecological restoration aimed at promoting biodiversity by emulating natural disturbances through restoration burning and artificial gap creation involving dead wood creation. In burned stands (n = 6) we removed up to 35% of the standing volume prior to burning, and in gap cut stands (n = 10) we removed the cut trees from every second gap; harvested trees covered costs for restoration. We used saproxylic and non-saproxylic beetles as a proxy for biodiversity to evaluate the two restoration methods. We compared species compositions of beetles collected with window traps one year before and one year after treatment. In addition, we compared catches in the treatments with those in untreated reference stands. Before treatment, we found no differences between the three groups of stands in terms of overall abundance, species richness or species composition. After treatment, the overall abundance of beetles was higher in the burned sites compared to the reference stands. Overall species richness was higher in burned stands compared to references and gap-cut stands. Gap-cut stands had higher species richness of cambivores and fire favoured species than reference stands. Species composition differed significantly between all three groups of stands. Among the 96 species that significantly contributed to the differences in species composition, 58 were more common in burned stands and 34 more common in gap-cut stands than in the other two stand groups. Nineteen of the 96 species are considered to be favored by forest fires, and 17 of these fire-favored species were more abundant in burned stands than gap-cut stands and/or references. Based on our results that burning and gap-cutting changed the beetle communities in partly different directions, we propose the use of both methods as complements to traditional conservation efforts in future attempts to improve conditions for biodiversity in managed boreal forest landscapes. [ABSTRACT FROM AUTHOR]

Topographic heterogeneity causes gradients in altitude, potential solar radiation and soil humidity on a range of scales from micro- to macro-habitat. These gradients are important determinants for the distribution of many organisms but have been largely neglected in studies of species associated with dead wood, a group of great conservation concern. In this study, we evaluated the effects of topography-related gradients (altitude, potential solar radiation and soil humidity) and habitat characteristics (bark cover, ground contact and dead wood volume) on saproxylic (wood-inhabiting) beetle assemblages. We sampled boreal saproxylic beetles hatching from 750 experimentally exposed spruce and birch logs in a regional scale field experiment including 10 landscapes and spanning gradients of altitude (range 85–510 m asl), potential solar radiation (based on slope and slope aspect and highest in equator-facing slopes, PADIR, range 0.24–0.71) and soil humidity (humidity index, range 2.3–3.1). The logs were placed in north Swedish forests and clear-cuts and beetles were sampled with emergence traps the 4th summer after the logs were introduced. Saproxylic assemblage composition varied considerably in response to altitude, potential solar radiation and soil humidity. The response was evident in both forests and clear-cuts and for both birch and spruce logs. Species density and abundance responses differed among trophic groups. For birch logs, fungivore species density increased significantly with increased potential solar radiation. For spruce logs, altitude affected total species density and density of cambium consumers positively and abundance of fungivores negatively, suggesting a delay in succession due to slower decomposition at higher altitudes. In addition to the topography-related gradients, ground contact and bark cover of logs as well as the availability of dead wood in the vicinity influenced the beetle assemblages. Our results clearly show that topography-related gradients affect assemblage composition of saproxylic beetles. These factors should be considered in the management of saproxylic biodiversity. To ensure the safeguarding of intact saproxylic assemblages it is important that the full range of dead wood habitats is conserved. Topographic heterogeneity may provide opportunities for landscape scale survival in response to rapid climate change but there is also a risk that some niches will disappear. Some of the negative effects of climate change could be mitigated by allocating set asides and restoration efforts in areas where gradient in altitude, solar radiation and soil humidity are particularly well developed over short distances. [ABSTRACT FROM AUTHOR]