Evaluation of window flight traps for effectiveness at monitoring dead wood-associated beetles: the effect of ethanol lure under contrasting environmental conditions

1 Subsequent to the diversity of saproxylic beetles being proposed as a management tool in forestry, more explicit knowledge about the efficiency and selective properties of beetle sampling methods is needed.
2 We compared saproxylic beetle assemblages caught by alcohol-baited or unbaited window traps in different forest contexts. Considering that trap attractiveness depends on kairomone concentrations, we appraised whether the trap efficiency was influenced by trap environment (openness and local supply of fresh dead wood).
3 Saproxylic beetles were sampled using 48 cross-vane window flight traps, arranged in paired designs (alcohol-baited/unbaited), in eight ancient and eight recent gaps (open stands), and eight closed-canopy control stands in an upland beech forest in the French Pyrenees.
4 Baited traps were more efficient than unbaited traps in terms of abundance and richness in our deciduous forests. The ethanol lure did not have any repellent effect on the individual response of saproxylic taxa.
5 The influence of local environmental conditions on trap attractiveness was observed. Openness had a significant moderate effect on species richness. Trap attractiveness was slightly reduced in the alcohol-saturated environment of recent gaps probably due to a disruption by local fresh dead-wood concentrations of the kairomonal response of saproxylic beetles to baited traps ('alcohol disruption').
6 Because the ethanol lure enhanced the probability of species detection, it may be useful in early-warning surveillance, monitoring and control of wood borers, despite slight influences of local conditions on baited trap efficiency.     

Saproxylic beetle diversity in a managed boreal forest: importance of stand characteristics and forestry conservation measures

Saproxylic beetles constitute a significant proportion of boreal forest biodiversity. However, the long history of timber production in Fennoscandia has significantly reduced the availability of dead wood and is considered a threat to the conservation of saproxylic beetle assemblages. Therefore, since the mid‐1990s dead wood retention in harvested stands has formed an integral part of silvicultural practices. However, the contribution of this biodiversity‐orientated management approach to conserving saproxylic beetle assemblages in boreal forest landscapes that include production forestry remains largely untested. We examined differences in resident saproxylic beetle assemblages among stands under different management in a boreal forest landscape in Central Sweden, and in particular stands managed according to new conservation‐orientated practices. We also investigated the relationship between beetle diversity and forest stand characteristics. Bark of coarse woody debris (CWD) was sieved for beetles in old managed stands, unmanaged nature reserves, and set‐aside areas, and clear‐cut stands harvested according to certification guidelines [new forestry (NF) clear‐cuts]. All stand types contributed significantly to the total diversity of beetles found. While stand size, position, and distance to nearest reserve were unimportant, both the quality and the quantity of CWD in stands contributed significantly to explaining beetle abundance and species richness. This extends the previous findings for red‐listed invertebrates, and shows that heterogeneous substrate quality and a range of management practices are necessary to maintain saproxylic beetle diversity in boreal forest landscapes that include production forestry. The unique abiotic conditions in combination with the abundant and varied CWD associated with NF clear‐cuts form an important component of forest stand heterogeneity for saproxylic beetles. It is thus essential that sufficient, diverse, CWD is retained in managed boreal landscapes to ensure the conservation of boreal saproxylic beetle assemblages.     

Effects of different tree harvesting intensities on saproxylic beetle diversity in coniferous and broad-leaved mixed forest in the Changbai Mountain,Northeast, China

1. Saproxylic beetles have gained increasing attention due to their role in the decomposition of rotting wood in forests. Studying the response of saproxylic beetles to tree harvesting is important for developing harvesting strategies that consider conservation of saproxylic beetle diversity.
2. We report results from a case study in which we designed four treatment stands to test the effects of forest harvesting intensity on saproxylic beetle diversity, harvest intensities of 0% untreated control (CK), 17.2% light harvest (LT), 34.7% moderate harvest (MT) and 51.9% high harvest (HT). Flight intercept traps were used to collect specimens of saproxylic beetles in each stand at 2, 3 and 4 years post-harvest.
3. The richness and abundance of saproxylic beetles were higher in MT and HT than in CK. Twelve of the 15 indicator species were significantly associated with MT or HT, whereas only three species were significantly associated with CK.
4. We found that moderate and high intensity harvesting affected the composition and increased beetle abundance and richness of saproxylic beetles, and light intensity harvesting had no effect on the beetle community in years 2, 3 and 4 post-harvest. There was no difference in the beetle community composition between moderate and high harvest stands.

     

Influence of macroclimate and local conservation measures on taxonomic,functional, and phylogenetic diversities of saproxylic beetles and wood-inhabiting fungi

Wood-inhabiting fungi and saproxylic beetles are threatened by habitat degradation. Our understanding of the importance of macroclimate and local factors determining their taxonomic diversity has increased, but determinants of functional and phylogenetic diversity are poorly understood. We investigated assemblages of wood-inhabiting fungi and saproxylic beetles along a 1000 m elevational gradient of a temperate low mountain range. We (i) tested the relative importance of macroclimate (i.e. elevation) and local variables (microclimate, i.e. canopy closure, amount and diversity of dead wood) in determining observed and rarefied diversities and (ii) explored whether determinants of observed functional and phylogenetic diversities match those of taxonomic diversity. For both taxa, the determinants of observed phylogenetic and functional diversities largely matched those of taxonomic diversity. The diversity of wood-inhabiting fungi was predominantly determined by local variables, whereas that of saproxylic beetles was determined by both local variables and elevation. Taxonomic and phylogenetic diversities of saproxylic beetles decreased with increasing elevation, but standardized functional richness and entropy of both groups increased with increasing elevation. Diversities of wood-inhabiting fungi increased with canopy closure, while diversities of saproxylic beetles decreased with increasing canopy closure. Microclimate and dead-wood amount and diversity affected the observed and rarefied diversity of both saproxylic taxa, which justifies conservation actions that focus on attributes of dead wood and canopy cover. The contrasting responses of fungi and beetles highlight the need for amounts of diverse dead wood in the various microclimates to preserve functional and phylogenetic diversities of saproxylic organisms.     

Increasing temperature may compensate for lower amounts of dead wood in driving richness of saproxylic beetles

Global warming and land‐use change are expected to be additive threats to global diversity, to which insects contribute the highest proportion. Insects are strongly influenced by temperature but also require specific habitat resources, and thus interaction between the two factors is likely. We selected saproxylic beetles as a model group because their life cycle depends on dead wood, which is highly threatened by land use. We tested the extent to which higher temperatures compensate for the negative effects of low amounts of dead wood on saproxylic beetle species richness (Temperature–Dead wood compensation hypothesis) on both a macroclimate and a topoclimate scale (north‐ and south‐facing slopes). We analyzed 1404 flight‐interception trap catches across Europe to test for interaction effects of temperature and dead‐wood amount on species richness. To experimentally test our findings from the activity trap data, we additionally reared beetles from 80 bundles of dead wood initially exposed at high and low elevations. At the topoclimate scale, we analyzed trap catches and reared beetles from dead wood exposed in 20 forest stands on south‐facing and north‐facing slopes in one region. On the macroscale, both temperature and dead‐wood amount positively affected total and threatened species richness independently, but their interaction was significantly negative, indicating compensation. On both scales and irrespective of the method, species richness decreased with temperature decline. Our observation that increasing temperature compensates for lower amounts of dead wood has two important implications. First, managers of production forests should adapt their dead‐wood enrichment strategy to site‐specific temperature conditions. Second, an increase in temperature will compensate at least partially for poor habitat conditions in production forests. Such a perspective contrasts the general assumption of reinforcing impacts of global warming and habitat loss on biodiversity, but it is corroborated by recent range expansions of threatened beetle species.     

Influence of tree hollow characteristics and forest structure on saproxylic beetle diversity in tree hollows in managed forests in a regional comparison

Tree hollows are among the rarest habitats in today''s Central European managed forests but are considered key structures for high biodiversity in forests. To analyze and compare the effects of tree hollow characteristics and forest structure on diversity of saproxylic beetles in tree hollows in differently structured managed forests, we examined between 41 and 50 tree hollows in beech trees in each of three state forest management districts in Germany. During the two‐year study, we collected 283 saproxylic beetle species (5880 individuals; 22% threatened species), using emergence traps. At small spatial scales, the size of hollow entrance and the number of surrounding microhabitat structures positively influenced beetle diversity, while the stage of wood mould decomposition had a negative influence, across all three forest districts. We utilized forest inventory data to analyze the effects of forest structure in radii of 50–500 m around tree hollows on saproxylic beetle diversity in the hollows. At these larger spatial scales, the three forest management districts differed remarkably regarding the parameters that influenced saproxylic beetle diversity in tree hollows. In Ebrach, characterized by mostly deciduous trees, the amount of dead wood positively influenced beetle diversity. In the mostly coniferous Fichtelberg forest district, with highly isolated tree hollows, in contrast, only the proportion of beech trees around the focal tree hollows showed a positive influence on beetle diversity. In Kelheim, characterized by mixed forest stands, there were no significant relationships between forest structure and beetle diversity in tree hollows. In this study, the same local tree hollow parameters influenced saproxylic beetle diversity in all three study regions, while parameters of forest structure at larger spatial scales differed in their importance, depending on tree‐species composition.     

Effect of deadwood management on saproxylic beetle richness in the floodplain forests of northern Italy: some measures for deadwood sustainable use

Saproxylic beetles may act as bio-indicators of high-quality mature woodlands, and their conservation is strongly linked to the quality and quantity of deadwood in a biotope. We tested the effect of deadwood accumulation and habitat variables on saproxylic species richness by investigating six sampling sites under different deadwood management practices that belong to both alluvial and riparian mixed forests of the Po plain, Italy. We sampled 43 obligate saproxylic species. The main factor predicting saproxylic species richness was the amount of deadwood measured by both log diameter and volume. We found a threshold of 0.22 m diameter (confidence interval CI 0.18–0.37 m) and 32.04 m³/ha volume (CI 16.09–64.09 m³/ha) below which saproxylic beetle richness would be significantly reduced and a threshold of 35 m³/ha dead wood volume (CI 33–40 m³/ha) over which species richness increases by <5 %. The other deadwood and environmental components influenced saproxylic beetle richness to a lesser extent; some of them, however, should still be considered for proper management. Forest structure variables describing forest density such as large trees and basal areas have a negative effect on species richness. According to the results of our study, stumps and advanced decaying class are positively correlated, while small logs are negatively correlated to species richness. Thus, in extensively managed forests, the regular cutting of trees should be implemented to create artificial stumps, in order to assure a continuity of deadwood and, in the meantime, increase the number and width of openings in the forest. Moreover, prolonging rotation times can assure the presence of deadwood at intermediate/later stages of decay.     

Mimicking natural disturbances of boreal forests: the effects of controlled burning and creating dead wood on beetle diversity

The young successional stages of boreal forests are an important habitat for many saproxylic species. These habitats are formed by disturbances such as forest fires and they are characterized by large volumes of dead wood and sun-exposed conditions. Today, young successional stages of natural origin are very rare in Fennoscandia and there is need for restoration. We constructed a large-scale field experiment in which we studied the effects of two restoration practices on beetle diversity: controlled burning and partial harvesting with creating different volumes of dead wood. We sampled beetles with flight-intercept traps recording a total of 56,031 individuals and 755 species. The species richness and abundance of both saproxylic and non-saproxylic beetles were increased by burning and harvesting but the volume of dead wood created on harvested sites had no short-term effect on species richness or abundance. Rare species, especially saproxylic ones, preferred burned sites and a similar trend was observed among red-listed and pyrophilous species. Burning and harvesting also resulted in different species assemblages and there were some additional differences according to the volume of dead wood. We conclude that fire can be successfully used in restoration of managed boreal forests to increase species diversity and to facilitate the recovery of declined species. However, long-term monitoring is needed to clarify the effects of the restoration practices, in particular those of creating dead wood without using fire.     

Influence of boreal forest succession and dead wood qualities on saproxylic beetles

1 Saproxylic insects, a functional group dominated by beetles, are dependent on dead or moribund trees as habitat elements. 2 Although there are few studies of saproxylic insects from the North American boreal zone, European studies demonstrate that forest harvest can lead to a biologically significant decrease in saproxylic beetle diversity. 3 We studied saproxylic beetles in the North American boreal mixedwood forest using flight intercept traps established on naturally dead and girdled trembling aspen and spruce trees along a successional gradient of undisturbed stands from deciduous to coniferous overstory trees. 4 Composition and diversity of beetle assemblages differed among forest successional types. 5 Snag age class was an important determinant of composition for saproxylic beetle assemblages. 6 Multivariate regression analysis of these data indicated that saproxylic beetles are responding to changes in coarse woody debris, and not to the relative densities of canopy tree species, although these variables are strongly correlated. 7 Coarse woody debris management should be a primary concern in forest management plans seeking to conserve saproxylic organisms and the critical ecosystem functions (i.e. nutrient cycling) in which they participate.     

The importance of substrate type, shading and scorching for the attractiveness of dead wood to saproxylic beetles

Modern forestry management has reduced the amount of dead wood in forest ecosystems and this has become a serious threat to flora and fauna. Efforts are therefore being made to reverse this trend but one problem is that we still lack detailed knowledge regarding the substrate requirements of many saproxylic species. In a field experiment, conducted in three forest types (forest reserve, mature managed forest and clear-cut), we evaluated the value, from a conservation perspective, of different substrate types (logs, snags and tops) of Norway Spruce, Picea abies, and if the quality of spruce logs as saproxylic habitats can be improved by simple log treatments (scorching and shading). We collected 9982 individuals representing 262 saproxylic beetle species in window traps. Both substrate type and, to a lesser extent, log treatment had a significant effect on the abundance and species richness of saproxylic beetles attracted to the different dead wood substrates. However, more importantly, the composition of the beetle assemblages differed significantly between both substrates and log treatments. Snags, logs and tops all attracted significantly different beetle assemblages and scorched logs differed from untreated control logs. Sixteen red listed species were trapped, with the highest number (11 species) being found on scorched logs. We found strong evidence that some species preferred a specific substrate type, mainly logs, in some cases treated logs (scorched or shaded), but not snags, the substrate commonly provided for conservation purposes on e.g. clear-cuts. This stresses the importance of conducting forestry in such a way that a multitude of both forest habitats and dead wood substrates are available continuously in the forest landscape to maintain biodiversity.     

Robinia pseudoacacia as a surrogate for native tree species for saproxylic beetles inhabiting the riparian mixed forests of northern Italy

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Sampling saproxylic beetle assemblages in dead wood logs: comparing window and eclector traps to traditional bark sieving and a refinement

The use of saproxylic beetle community as a metric to evaluate nature conservation measures in forests requires efficient methods. We first compare traditional bark sieving to a potential improvement (extracting beetles from whole bark with Tullgren funnels) to determine the most efficient. Secondly we compare this most efficient bark sampling to eclector and window traps. At the species, family, and functional group levels, we consider species richness, abundance and practical aspects. Traditional bark sieving missed >50% of the individual beetles compared to whole bark sampling so we recommend the latter. Window traps caught large numbers of mobile saproxylic beetles, but a high proportion of non-saproxylics results in high sorting cost; bark sampling and eclector traps had a high proportion of saproxylics and obligate saproxylics. Compared to bark sampling, eclector traps are non-destructive, and monitor the whole saproxylic assemblage (i.e. also beetles inside the wood). Overall, window traps are useful because they capture saproxylic beetles attracted to dead wood and sample the local species pool, whereas eclector traps capture the saproxylics that actually emerge from a particular piece of dead wood, and thus are suited to detailed studies. Overall, we suggest that a combination of these two best methods is highly complementary.     

Linking taxonomical and functional biodiversity of saproxylic fungi and beetles in broad‐leaved forests in southern Italy with varying management histories

Abstract

The fundamental ecological significance of deadwood decomposition in forests has been highlighted in several reviews, some conclusions regarding silviculture being drawn. Old‐growth forests are natural centres of biodiversity. Saproxylic fungi and beetles, which are vital components of these ecosystems, occupy a variety of spatial and trophic niches. Fungal and beetle diversity on coarse woody debris (CWD) was analysed in 36 forest sites in the Cilento and Vallo di Diano National Park, Italy. The data were analysed by DCA and Spearman’s rank correlation. The results provide empirical evidence of the existence of a pattern of joint colonization of the woody substrate by fungi and beetles, which includes an assemblage of reciprocal trophic roles within fungal/beetle communities. These organisms act together to form a dynamic taxonomical and functional ecosystem component within the complex set of processes involved in wood decay. The variables most predictive of correlations between management‐related structural attributes and fungal/beetle species richness and their trophic roles for old‐growth forest are: number of logs, number of decay classes and CWD total volume. Deadwood spatio‐temporal continuity should be the main objective of forest planning to stop the loss of saproxylic fungal and insect biodiversity.     

What factors influence the diversity of saproxylic beetles? A multiscaled study from a spruce forest in southern Norway

The diversity in different groups of obligate saproxylic beetles was related to ecological variables at three levels of spatial scale in mature spruce-dominated forest. The variables were connected to: (i) decaying wood, (ii) wood-inhabiting fungi, (iii) the level of disturbance, (iv) landscape ecology, and (v) vegetational structure. Several strong relationships were found at medium (1 km²) and large scales (4 km²), while only weak relationships were found at a small scale (0.16 ha; 1 ha=10⁴ m²). This may be explained by the local variations in habitat parameters and the high mobilities of many beetle species. Factors connected to decaying wood and wood-inhabiting fungi were clearly the most important factors at all scale levels. In particular, the variables diversity of dead tree parts, number of dead trees of large diameter and number of polypore fungi species increased the species richness of many groups and increased the abundance of many species. Eight species were absent below a certain density of decaying wood per 1 or 4 km². Former extensive cutting was a negative factor at large scale, probably because of decreasing recolonization with increasing distance to the source habitats. Thinning reduced the diversity of species associated with birch. The development of guidelines favouring the diversity of saproxylic beetles are discussed below.     

Micro and macro-habitat associations in saproxylic beetles: implications for biodiversity management

Restoration of habitats is critically important in preventing full realization of the extinction debt owed as a result of anthropogenic habitat destruction. Although much emphasis has been placed on macrohabitats, suitable microhabitats are also vital for the survival of most species. The aim of this large-scale field experiment was to evaluate the relative importance of manipulated microhabitats, i.e., dead wood substrates of spruce (snags, and logs that were burned, inoculated with wood fungi or shaded) and macrohabitats, i.e., stand types (clear-cuts, mature managed forests, and forest reserves) for species richness, abundance and assemblage composition of all saproxylic and red-listed saproxylic beetles. Beetles were collected in emergence traps in 30 forest stands in 2001, 2003, 2004 and 2006. More individuals emerged from snags and untreated logs than from burned and shaded logs, but species richness did not differ among substrates. Assemblage composition differed among substrates for both all saproxylics and red-listed saproxylic species, mainly attributed to different assemblage composition on snags. This suggests that the practise of leaving snags for conservation purposes should be complemented with log supplementation. Clear-cuts supported fewer species and different assemblages from mature managed forests and reserves. Neither abundance, nor species richness or assemblage composition differed between reserves and mature managed forests. This suggests that managed stands subjected to selective cutting, not clear-felling, maintain sufficient old growth characteristics and continuity to maintain more or less intact assemblages of saproxylic beetles. Thus, alternative management methods, e.g., continuity forestry should be considered for some of these stands to maintain continuity and conservation values. Furthermore, the significantly higher estimated abundance per ha of red-listed beetles in reserves underlines the importance of reserves for maintaining viable populations of rare red-listed species and as source areas for saproxylic species in boreal forest landscapes.     

The influence of forest stand and site characteristics on the composition of exotic dominated ambrosia beetle communities (Coleoptera: Curculionidae: Scolytinae)

Economic and biological consequences are associated with exotic ambrosia beetles and their fungal associates. Despite this, knowledge of ambrosia beetles and their ecological interactions remain poorly understood, especially in the oak-hickory forest region. We examined how forest stand and site characteristics influenced ambrosia beetle habitat use as evaluated by species richness and abundance of ambrosia beetles, both the native component and individual exotic species. We documented the species composition of the ambrosia beetle community, flight activity, and habitat use over a 2-yr period by placing flight traps in regenerating clearcuts and older oak-hickory forest stands differing in topographic aspect. The ambrosia beetle community consisted of 20 species with exotic ambrosia beetle species dominating the community. Similar percentages of exotic ambrosia beetles occurred among the four forest habitats despite differences in stand age and aspect. Stand characteristics, such as stand age and forest structure, influenced ambrosia beetle richness and the abundances of a few exotic ambrosia beetle species and the native ambrosia beetle component. Topographic aspect had little influence on ambrosia beetle abundance or species richness. Older forests typically have more host material than younger forests and our results may be related to the amount of dead wood present. Different forms of forest management may not alter the percent contribution of exotic ambrosia beetles to the ambrosia beetle community.     

Fast but ephemeral effects of ecological restoration on forest beetle community

Many protected areas have a long history of human intervention before being protected. In protected forests, the past land use has reduced the amount of natural structures, which are crucial substrates for thousands of species. We evaluate the short-term ecological effect of forest restoration (dead wood creation) on conifer-associated saproxylic (dead-wood dependent) beetles. More specifically, we analyze the effect of dead wood creation on the number of beetle species and individuals 1 and 5 years after restoration in spruce and pine forests, using a large-scale monitoring network over Finland. The number of saproxylic beetle species and individuals was larger at restored than at control plots both 1 and 5 years after restoration in both spruce and pine forests. Community composition in restored plots was different from control plots 1 year after restoration, but had returned towards the control plot composition 5 years after restoration, while control plots remained largely unchanged. Both in spruce and pine forests, there were more red-listed and rare saproxylic beetles in restored than in control plots 1 and 5 years after restoration. Our results indicate that restoration has an overall positive influence on saproxylic beetle diversity immediately after dead wood creation, but this effect is rather short-lived. Long term monitoring of restored dead wood is crucial in investigating successional pathways as well as biotic communities in advanced decay stages, and in fully evaluating the ecological effect of dead wood creation as a forest restoration measure.     

The species richness of click beetles in ancient pasture woodland benefits from a high level of sun exposure

Forests support high concentrations of species and beetles in particular are often used to evaluate forest biodiversity. Ancient pasture woodlands are facing a major decline in Europe mainly due to the abandonment of traditional management and subsequent succession. We studied click beetles (Coleoptera: Elateridae) in one of the largest central-European remnants of pasture woodland in Lány Game Park (Czech Republic) using flight interception traps placed at standing veteran trees. The gradient of sun-exposure, circumference of stem, height and vitality of tree and tree species were studied in relation to the species richness of click beetles and their ecological groups. Total species richness reached nearly one half of the recently documented fauna in the study area and species accumulations showed us that the majority of species were represented. Most species preferred solitary trees in sun-exposed habitats and avoided shaded trees in closed canopies. The same results were obtained for ecological groups, such as saproxylic and non-saproxylic species, functional groups and guilds. Our results showed that the species richness of one of the most ecologically diverse beetle families, click beetles, benefits from a high level of sun exposure. Thus, the long spatial and temporal continuity of sun-exposed veteran trees could be a good predictor for sustainable forest management.     

Ecologie des coléoptères saproxyliques dans les forêts de l’étage montagnard des Alpes du nord françaises

Ecology of the saproxylic beetles in mountain forests of the northern French Alps. Both saproxylic beetles and deadwood stocks were studied in order to detect special deadwood features important for these organisms, and to better understand their ecology. A total of 37 window traps were used in ten stations covering four mountain forests in the French northern Alps. In the same time, the deadwood stocks were inventoried in the ten stations. 181 m³ of deadwood (1219 fragments) were measured and 4268 individuals belonging to 235 saproxylic species were trapped. The deadwood volume ranges from 21.1 to 233.6 m³/ha and the number of beetle species from 27 to 113. A positive relation was observed between the stand age, the whole volume of deadwood and the species richness of saproxylic beetles. However, in some deadwood rich sites the beetle diversity is not as high as expected. This was explained by the negative influence of the management history of the forest. The compositions of saproxylic communities depend also of some characteristics of the deadwood stocks. Xylophagous and zoophagous species prefer “not lying and recently dead softwood” while the mycophagous and saproxylophagous species are strongly dependent on fungi growing on hardwood, respectively under “large surfaces of barks” and in “large woody debris”. Surprisingly, the majority of the saproxylic beetles living on softwood does not depend on the most represented resinous deadwood type: the “decayed and lying softwood”.     

Are there saproxylic beetle species characteristic of high dead wood connectivity?

Saproxylic beetles have been shown to be vulnerable to within-forest fragmentation expressed as large distances between single dead wood pieces (low spatial connectivity of dead wood). From samples of a two-year study of saproxylic beetles, species that were characteristic of sites with high dead wood connectivity were identified by Canonical Correspondence Analysis, the method of Dufrêne and Legendre (IndVal) and by considering the species occurring exclusively in sites with high dead wood connectivity. These species differed mainly from the other species by their high habitat specificity. Hence, there arc species-specific responses of saproxylic beetles to the spatial arrangement of dead wood. High dead wood connectivity must be achieved in managed forests to sustain species which are particularly vulnerable to fragmentation.