Use of arthropod rarity for area prioritisation: insights from the Azorean Islands

We investigated the conservation concern of Azorean forest fragments and the entire Terceira Island surface using arthropod species vulnerability as defined by the Kattan index, which is based on species rarity. Species rarity was evaluated according to geographical distribution (endemic vs. non endemic species), habitat specialization (distribution across biotopes) and population size (individuals collected in standardized samples). Geographical rarity was considered at 'global' scale (species endemic to the Azorean islands) and 'regional' scale (single island endemics). Measures of species vulnerability were combined into two indices of conservation concern for each forest fragment: (1) the Biodiversity Conservation Concern index, BCC, which reflects the average rarity score of the species present in a site, and (2) one proposed here and termed Biodiversity Conservation Weight, BCW, which reflects the sum of rarity scores of the same species assemblage. BCW was preferable to prioritise the areas with highest number of vulnerable species, whereas BCC helped the identification of areas with few, but highly threatened species due to a combination of different types of rarity.A novel approach is introduced in which BCC and BCW indices were also adapted to deal with probabilities of occurrence instead of presence/absence data. The new probabilistic indices, termed pBCC and pBCW, were applied to Terceira Island for which we modelled species distributions to reconstruct species occurrence with different degree of probability also in areas from which data were not available. The application of the probabilistic indices revealed that some island sectors occupied by secondary vegetation, and hence not included in the current set of protected areas, may in fact host some rare species. This result suggests that protecting marginal non-natural areas which are however reservoirs of vulnerable species may also be important, especially when areas with well preserved primary habitats are scarce.     

Island biogeography of urban insects: tenebrionid beetles from Rome tell a different story

Tenebrionid beetle records from 55 sites in urban Rome (Italy) were used to study the influence of structural parameters (area, isolation, forest cover, and shape) of green spaces on species richness and extinction trends. In line with biogeographical predictions, species richness correlated positively with area size of green spaces, extinction was enhanced by isolation and hindered by area size, but, in contrast with common findings, forest extent had a negative impact on tenebrionid persistence. This is explained by the fact that most of tenebrionid species from Rome are associated with open habitats typical of the landscape that characterized the study area before modern urbanization. In contrast with results obtained in other studies of urban ecology, distance to city centre (which expresses the urban–rural gradient) was never recovered as an important correlate of tenebrionid richness or extinction, which may be explained by the fact that tenebrionids include both urban avoider and urban adapter species. These results warn against making generalizations on urban diversity patterns and conservation strategies without reference to past land-use and species characteristics.     

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.     

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.     

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.     

Diversity distribution of saproxylic beetles in Chilean Mediterranean forests: influence of spatiotemporal heterogeneity and perturbation

Mediterranean ecosystems have been recognized as a priority for biodiversity conservation due to their high levels of species richness and endemism. In South America, these environments are restricted to central Chile and represent a biodiversity hotspot. The study of saproxylic beetles in this area is an unexplored topic, despite the ecological role they play in these ecosystems and their potential usefulness for monitoring the degree of forest conservation. We investigated the diversity distribution of trophic guilds of saproxylic beetles in Chilean Mediterranean forests, to identify the main environmental variables that influence their distribution. We also analyzed seasonal dynamics as a key factor influencing insect communities and the effect of human disturbance on their diversity and composition. We identified characteristic species of perturbation degree as bioindicators for habitat monitoring. A total of 40 window traps were used to survey three Mediterranean forest types in the Río Clarillo National Reserve and the adjacent non-protected areas. We found that the diversity, abundance and composition of saproxylic beetles varied significantly spatiotemporally among the studied forest types and among perturbation degrees, showing different patterns depending on the trophic guild. Results indicated that conservation decisions should include the preservation of a larger range of different vegetation types and the nearby zones that have suffered low levels of disturbance or fragmentation and where actions promoting the presence of old native trees would have a significant conservation value.     

Biodiversity conservation in old-growth boreal forest: black spruce and balsam fir snags harbour distinct assemblages of saproxylic beetles

Biodiversity conservation of forest ecosystems strongly relies on effective dead wood management. However, the responses of saproxylic communities to variations in dead wood characteristics remains poorly documented, a lack of knowledge that may impede the development of efficient management strategies. We established the relationship between saproxylic beetles—at the species and community levels—and attributes of black spruce and balsam fir in old-growth boreal forests. The relationship was first evaluated for individual snag bole segments, and then for forest stands. A total of 168 bole sections were collected in summer 2006 along a compositional gradient ranging from black spruce-dominated stands to balsam fir-dominated ones, in a boreal forest dominated by >90-year-old stands. A total of 16,804 beetles belonging to 47 species emerged from bole segments, with 21% of the species being found exclusively in black spruce snags and 36% exclusively in balsam fir snags. Black spruce and balsam fir snags thus contributed differently to forest biodiversity by being inhabited by different saproxylic communities. Wood density was an important attribute in the host-use patterns for several species of saproxylic beetles, but no relationship was found between snag availability within stands and abundance of beetles strongly linked to either black spruce or balsam fir. Our study outlines the relative contribution of tree compositional diversity to saproxylic species, while highlighting the contribution of black spruce and balsam fir to animal diversity in old-growth boreal forests.     

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.     

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.     

The diversity of beetle assemblages in different habitat types in Sabah, Malaysia

The diversity of beetle assemblages in different habitat types (primary forest, logged forest, acacia plantation and oil palm plantation) in Sabah, Malaysia was investigated using three different methods based on habitat levels (Winkler sampling, flight-interception-trapping and mist-blowing). The overall diversity was extremely high, with 1711 species recorded from only 8028 individuals and 81 families (115 family and subfamily groups). Different degrees of environmental changes had varying effects on the beetle species richness and abundance, with oil palm plantation assemblage being most severely affected, followed by acacia plantation and then logged forest. A few species became numerically dominant in the oil palm plantation. In terms of beetle species composition, the acacia fauna showed much similarity with the logged forest fauna, and the oil palm fauna was very different from the rest. The effects of environmental variables (number of plant species, sapling and tree densities, amount of leaf litter, ground cover, canopy cover, soil pH and compaction) on the beetle assemblage were also investigated. Leaf litter correlated with species richness, abundance and composition of subterranean beetles. Plant species richness, tree and sapling densities correlated with species richness, abundance and composition of understorey beetles while ground cover correlated only with the species richness and abundance of these beetles. Canopy cover correlated only with arboreal beetles. In trophic structure, predators represented more than 40% of the species and individuals. Environmental changes affected the trophic structure with proportionally more herbivores (abundance) but fewer predators (species richness and abundance) in the oil palm plantation. Biodiversity, conservation and practical aspects of pest management were also highlighted in this study.     

Different effects of coarse woody material on the species diversity of three saproxylic beetle families (Cerambycidae, Melandryidae, and Curculionidae)

The relationships between coarse woody material (CWM) and the diversity of three saproxylic beetle families (Cerambycidae, Melandryidae, and Curculionidae) were investigated. These three families responded differently toward the quality and quantity of CWM. The species richness of cerambycid beetles increased in forests with more CWM in the early stage of decomposition. The richness of saproxylic curculionids increased in stands with more tree species. No clear trend was evident for melandryid diversity. The CWM differed in quality and quantity among three forest types [middle-aged larch (Larix kaempferi [Lamb.] Carrière) plantation, secondary forest, and old-growth forest] and between two forest-management practices (thinning and long rotation). Forest type and management practices affected CWM and the number of tree species, and CWM and the number of tree species influenced the diversity of saproxylic families differently. Because each decomposition stage is considered to be important for saproxylic beetles at the species level, a constant supply of CWM is necessary to maintain a suitable balance of CWM through these decomposition stages in forests to maintain the diversity of saproxylic beetles.     

基于生态单元制图的宝鸡市城区生物多样性保护规划研究

为探寻适合我国城乡生物多样性保护的有效措施和方法,以宝鸡城区为研究对象,通过实地调研和室内制图相结合的研究方法,创建一套融入植被结构因子(植被水平结构因子、植被优势种的年龄因子、植被垂直结构因子、林木类型因子)的生态单元分类系统,将研究区域内的城市绿地现状以图谱形式表示。通过对不同植被结构的绿地中维管束植物物种丰富度的对比,以检验此分类系统在城乡生物多样性信息采集中的有效性。基于制图信息和检验结果,分析研究区域内绿地空间结构存在的问题并针对宝鸡市城乡生物多样性保护提出相应策略,以期为今后我国城乡生物多样性保护提供理论依据和实践方法。     

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.

     

Can 'continuity indicator species' predict species richness or red-listed species of saproxylic beetles?

This study investigates the relationship between the abundance of wood-rotting fungus suggested as 'continuity indicator species' and environmental variables for the assemblage of saproxylic (wood-living) beetles associated with Fomitopsis pinicola fruiting bodies in a mature spruce forest in southeastern Norway. The presence of species thought to indicate continuity in old growth is one of the criteria used when finding and delineating small protected areas ('woodland key habitats') in Scandinavian forestry. Although it is clear that remnants of old-growth forest are important for many taxa, documentation as to which entities or species the indicator species indeed indicate is scarce. If stands with a continuous and unbroken input of dead wood have a unique assemblage of wood-rotting fungi, it seems relevant to ask if these stands also have a unique assemblage of rare saproxylic beetles. I find that the indicator species exhibit no significant correlations with beetle species richness or with the presence of red-listed saproxylic beetles as a group. The different characteristics of dead wood conditions are the most important environmental variables that explain both the species richness and the presence of red-listed beetles. Single-species analyses reveal contrasting relationships. The red-listed beetle Atomaria alpina shows a significant and positive association to the abundance of indicator species. Contrary, a group of three red-listed species with similar ecology in the family Cisidae exhibits a significant and negative association to indicator species abundance. This indicates that important patterns are concealed when considering general measures such as overall presence of red-listed beetles. Single-species studies are necessary in order to correctly understand how rare beetles respond to forestry activities and to develop a policy that can secure their continuing existence in the boreal forest.     

Forest restoration by burning and gap cutting of voluntary set-asides yield distinct immediate effects on saproxylic beetles

Today, the importance of restoring natural forest disturbance regimes and habitat structures for biodiversity is widely recognized. We evaluated the immediate effects of two restoration methods on wood-inhabiting (saproxylic) beetles in boreal forest voluntary set-asides. We used a before-after control-impact experimental set-up in 15 set-asides; each assigned to one of three treatments: (1) restoration burning, (2) gap cutting and (3) no-treatment reference stands. Before treatment, abundance, species richness and assemblage composition of trapped beetles did not differ significantly among treatments. Burning resulted in a significant change in assemblage composition and increased species richness and abundance compared to reference stands. As predicted, saproxylic species known to be fire favoured increased dramatically after burning. The immediate response shows that, initially, fire favoured species are attracted from the surrounding landscape and not produced on site. Gap cutting increased the abundance of cambium consumers but had no significant effect on total species richness or assemblage composition of saproxylic beetles. The stronger effect of burning compared to gap cutting on saproxylic assemblages is probably due to the very specific conditions created by fires that attracts many disturbance-dependent species, but that at the same time disfavour some disturbance-sensitive species. By contrast, gap cutting maintained assemblage composition, increased abundances and is likely to increase species richness in the years to follow, due to elevated level of dead wood. The restoration methods applied in this study may prove particularly useful, partly because of positive effect on saproxylic beetles, but also due to the cost-efficiency of the measures; the voluntary set-asides were already established and the restoration costs fully covered by revenue from the extracted timber.     

Does selective logging change ground‐dwelling beetle assemblages in a subtropical broad‐leafed forest of China?

Selective logging with natural regeneration is advocated as a near‐to‐nature strategy and has been implemented in many forested systems during the last decades. However, the efficiency of such practices for the maintenance of forest species are poorly understood. We compared the species richness, abundance and composition of ground‐dwelling beetles between selectively logged and unlogged forests to evaluate the possible effects of selective logging in a subtropical broad‐leafed forest in southeastern China. Using pitfall traps, beetles were sampled in two naturally regenerating stands after clearcuts (ca. 50 years old, stem‐exclusion stage: selectively logged 20 years ago) and two mature stands (> 80 years old, understory re‐initiation stage: selectively logged 50 years ago) during 2009 and 2010. Overall, selective logging had no significant effects on total beetle richness and abundance, but saproxylic species group and some abundant forest species significantly decreased in abundance in selectively logged plots compared with unlogged plots in mature stands. Beetle assemblages showed significant differences between selectively logged and unlogged plots in mature stands. Some environmental characteristics associated with selective logging (e.g., logging strategy, stand age, and cover of shrub and moss layers) were the most important variables explaining beetle assemblage structure. Our results conclude that selective logging has no significant impacts on overall richness and abundance of ground‐dwelling beetles. However, the negative effects of selective logging on saproxylic species group and some unlogged forest specialists highlight the need for large intact forested areas for sustaining the existence of forest specialist beetles.     

Habitat influences on urban avian assemblages

Urbanization is increasing across the globe and there is growing interest in urban ecology and a recognition that developed areas may be important for conservation. We review the factors influencing urban avian assemblages, focusing on habitat type and anthropogenic resource provision, and analyse data from a common bird monitoring scheme to assess some of these issues. The review suggests that (1) local factors are more important than regional ones in determining the species richness of urban avian assemblages, raising the potential for the management of urban sites to deliver conservation; (2) habitat fragmentation frequently influences urban avian assemblages, with the effects of patch size being greater than those of isolation, and (3) urban bird assemblages appear to respond positively to increasing the structural complexity, species richness of woody vegetation and supplementary feeding, and negatively to human disturbance. Data from Britain's Breeding Bird Survey, combined with habitat data obtained from aerial photographs, were used to assess a number of these issues at the resolution of 1‐km squares. Green‐space constituted 45% of these squares, and domestic gardens contributed 50% of this green‐space, though their contribution to large continuous patches of green‐space was negligible. There was no significant positive correlation between the densities of individual species in urban areas and surrounding rural areas. Rural species richness declined with increasing latitude, but urban species richness was not correlated with latitude. This contrast contributes to slightly higher avian species richness in rural squares in Southern England than urban ones. Occupancy and abundance were strongly positively correlated in urban avian assemblages, and some indicator species of conservation concern occurred in few urban areas and at low densities. Such species will require conservation action to be precisely targeted within urban areas. Of the urban indicators of conservation concern, only the House Sparrow Passer domesticus and Common Starling Sturnus vulgaris were more abundant in urban than rural areas. Moreover, the densities of these two species were strongly and positively correlated, indicating that they may be limited by shared resources, such as nest‐sites or supplementary food. There was little evidence that high densities of nest‐predating corvids were associated with reduced densities of their prey species. Species richness and the densities of individual species frequently declined with an increasing number of buildings. Current trends for the densification of many British urban areas are thus likely to be detrimental for many bird species.     

Deadwood as a surrogate for forest biodiversity: Meta-analysis of correlations between deadwood volume and species richness of saproxylic organisms

Deadwood is an important component of forest ecosystems on which many forest dwelling species depend. Deadwood volume is therefore widely used as an indicator of forest biodiversity, notably throughout Europe. However, using deadwood as an indicator has mostly been based on boreal references, and published references for temperate forests are scarce. As a result, the magnitude of the relationship between deadwood volume and species richness remains unclear for saproxylic species. We used meta-analysis to study the correlation between deadwood volume and the species richness of saproxylic beetles and fungi relative to several predictors at the forest stand level: biome, type of deadwood (log, snag, and stump) and decay class (fresh vs. decayed). We showed that the correlation between deadwood volume and species richness of saproxylic organisms was significant but moderate (r = 0.31), and that it varied only slightly between logs and snags or between decay stages. However, we found a strong biome effect: deadwood volume and species richness were more correlated in boreal forests than in temperate forests. This could be attributed both to differences in the history of forest management between biomes and to varying landscape patterns. Finally, we conclude that total deadwood volume is probably not a sufficient indicator of saproxylic biodiversity, and those additional variables (notably at the landscape level) such as type of deadwood or decay class should be integrated in deadwood monitoring. In addition, further forest research is needed to better assess the quantitative relationship between deadwood and saproxylic biodiversity, and in order to build indicators adapted to different biome contexts.     

Horizontal and vertical distribution of saproxylic beetles (Col., Buprestidae, Cerambycidae, Scolytinae) across sections of forest edges

Abstract:  We evaluated the preferred home ranges of three saproxylic beetle taxa along transects from the open field into the forest interior, and from the forest floor up to the canopy. By means of trap sets on metal scaffolds, vertical and horizontal strata were sampled across two types of forest edges: soft-edge ecotones with a gradual transition from the field into the forest and hard edges with an abrupt transition. The forest edges consisted of different strata such as herbaceous fringe, shrub belt, unmanaged forest and managed forest. The thermophilic buprestids were mainly caught in the open land (herbaceous fringe and agricultural land) and in the upper forest mantle. In general, the cerambycids were most abundant in the open land and the lower forest mantle, but a few species favoured the forest interior. The bark beetles (Scolytinae) were equally distributed in all habitats. These distribution patterns of the taxa were observed in terms of both species numbers and abundances. Each species with at least five collected specimens was assigned to one of the three habitat types: open land, forest mantle and forest interior. Of 74 ranked species, only 16% were prevalent in the forest interior and are thus considered to be true forest species. The other 84% of the species were attributed to open land or the forest mantle and are, therefore, forest edge species. Soft forest edges generally supported a higher species richness than hard edges, particularly as regards Cerambycidae and Scolytinae. In terms of Shannon diversity, soft edges tended to be more diverse in buprestids and cerambycids. Overall, the forest interior showed the least species richness and diversity. Therefore, for the conservation of saproxylic beetles, not only the amount and quality of dead wood is important, but also the presence and design of forest boundary structures.     

Saproxylic beetle assemblages related to silvicultural management intensity and stand structures in a beech forest in Southern Germany

Compared to agricultural land and spruce plantations, central European beech-oak forests are often relatively close to natural conditions. However, forest management may alter these conditions. In Steigerwald, southern Germany, a large beech-dominated forest area, three management intensities were applied during the past 30–70 years. Here, we examined the influence of management intensity on saproxylic beetles in >100-year old mature stands at 69 sampling plots in 2004. We sampled beetles using flight-window traps and time standard direct searches. The community structure based on presence/absence data changed remarkably along the gradient from unmanaged to low-intensity to high-intensity management, but these differences were not evident using abundance data from flight interception traps. Saproxylic species richness decreased in intensively managed forests. Elateridae and threatened species richness peaked in unmanaged forests and in forests under low-intensity management. Saproxylic species richness was dependent on certain micro-habitat factors. These factors were (1) the amount of dead wood for Elateridae, overall and threatened saproxylic beetle richness; (2) the amount of flowering plants for Cerambycidae; (3) the richness of wood-inhabiting fungi for Staphylinidae, Melandryidae and overall saproxylic beetle richness; and (4) the frequency of Fomes fomentarius for threatened species. Species richness was better explained by plot factors, such as dead wood or fungi, than by management intensity. These results suggest that the natural variation of dead wood niches (decay stages, snag sizes, tree cavities and wood-inhabiting fungi species) must be maintained to efficiently conserve the whole saproxylic beetle fauna of beech forests. Also, intensive management may alter the specialised saproxylic beetle community even if the initial tree-species composition is maintained, which was the case in our study. For monitoring the ecological sustainability of forest management we must focus on threatened species. If structures alone are sampled then the amount of dead wood is the best indicator for a rich saproxylic beetle fauna.