Effects of fen management and habitat parameters on staphylinid beetle (Coleoptera: Staphylinidae) assemblages in north-eastern Germany

Because fens have undergone dramatic declines in recent decades, an important question is which management regimes and habitat parameters are most effective in preserving fen biodiversity. The aim of the present study was to assess the effects of five different management regimes (intensive grassland, moist meadows, summer harvested sites, winter harvested sites, fallows) on staphylinid beetle assemblages. During the study period 5,989 individuals from 92 staphylinid beetle species were recorded. Species richness and abundance were highest on intensive grassland and fallows, and water level and vegetation height had significant impacts on the abundance of staphylinids. On winter-harvested sites species richness and abundance were lowest. In general, staphylinid beetles did not show pronounced variation among management regimes, while the environmental factors water level, vegetation height and top soil mineralisation seemed to have a larger structuring impact. The number of threatened species and the conservation index were highest on summer-harvested sites and fallows, representing fairly well-preserved fens. We conclude that summer harvest of reed beds or no management at all appears to be most beneficial for the conservation of staphylinid beetles.     

Winter quarters of wetland ground beetles (Coleoptera,Carabidae) in South Scandinavia

Sites at various distances from eutrophic and mesotrophic lakes and fens on the island Öland in southern Sweden were systematically surveyed in summer (May–August) and autumn (late September–October) to elucidate the hibernation sites of wetland carabid beetles. Thirty-five of 47 wetland species were found in their winter quarters. In areas ≤50 m from the lakes and fens, the observed as well as the estimated number of hibernating wetland species was higher in mesic to dry sites than in wet or moist open sites. Very few overwintering beetles were detected far (≥120 m) from the water. There was no significant difference in the frequencies of macropterous and dimorphic (brachypterous) species and individuals hibernating close to, and more distantly from, water. Individuals of small species hibernated closer to water than larger ones. At least in Scandinavia, there is no convincing evidence that wetland species hibernate far away from water, migrating by flight. A considerable number of the species that were collected in their winter quarters are rare and red- listed in at least one of the Scandinavian countries. Winter quarters situated in mesic and dry meadows and woodland close to lakes and fens had the highest number of red-listed species. Therefore, it is of fundamental importance to protect such sites. Threats to the integrity of the current habitats are logging and various transformations of meadows, e.g. digging and removal of large objects such as stones. Cessation of grazing by cattle may also have a negative effect.     

The role of various meadow margin types in shaping carabid and staphylinid beetle assemblages (Coleoptera: Carabidae,Staphylinidae) in meadow dominated landscapes

Less intensively managed semi-natural habitats, e.g., field and meadow margins like hedgerows, are thought to be crucial landscape components for maintaining biodiversity in highly disturbed and intensively managed agricultural landscapes. In this study, we focused on the effects of three meadow margin types on activity-density, species richness and species composition of carabid and staphylinid beetles recorded by pitfall traps in Central European landscapes dominated by intensively managed meadows. Carabid activity-density was significantly higher in meadows than in meadow margins and within meadow margins their activity-density increased from grassy meadow margins via shrubby ones to woody meadow margins. We found that recorded species richness of both carabid and staphylinid beetles was not significantly affected by habitat identity (meadow margin or neighbouring meadow) and meadow margin type. Recorded species composition of both investigated taxa was significantly affected by habitat identity and interaction between habitat identity and meadow margin type (i.e. it differed between particular meadow margin types). Assemblages inhabiting various meadow margin types were more dissimilar between each other than assemblages from neighbouring meadows. Meadow margins within grassland dominated landscapes maintain local species richness by hosting different species from those living in surrounding meadows. Dissimilarity of carabid and staphylinid assemblages from meadows neighbouring both sides of particular meadow margin did not differ between meadow margin types. Our results indicate that semi-natural habitats play an important role in maintaining biodiversity not only in agricultural landscapes dominated by arable fields, but also in those dominated by meadows.     

Measuring the efficiency of fen restoration on carabid beetles and vascular plants: a case study from north‐eastern Germany

The aim of the study was to assess the effects of fen rewetting on carabid beetle and vascular plant assemblages within riverine fens along the river Peene in north‐eastern Germany. Drained (silage grassland), rewetted (restored formerly drained silage grassland), and near‐natural (fairly pristine) stands were compared. Eighty‐four beetle species (7,267 individuals) and 135 plant species were recorded. The richness of vascular plant species and the number of endangered species were highest on near‐natural fens. Fourteen years of rewetting did not increase plant species numbers compared with drained fens. For carabid beetles, however, species richness and the number of stenotopic species were highest on rewetted fens. Rewetting caused the replacement of generalist carabids by wetland specialists, but did not provide suitable habitat for specialist fen carabids or for plant species of oligo‐ or mesotrophic fen communities. Therefore, raising the water table on fens with nutrient‐rich, degraded peat was not sufficient for restoring species assemblages of intact fens, although water level was the most important environmental factor separating species assemblages. Our study illustrated that insects and plants may respond differentially to restoration, stressing the need to consider different taxa when assessing the efficiency of fen restoration. Furthermore, species assemblages of intact fens could not be restored within 14 years, highlighting the importance of conserving pristine habitat.     

Turlough ground beetle communities: the influence of hydrology and grazing in a complex ecological matrix

Turloughs are groundwater dependent grazed wetlands of conservation importance that occur in limestone depressions in the karst landscape, mostly in the west of Ireland. Data on Carabidae, hydrological regime, soils and management (using grazing exclosures) were collected to assess the effects of both hydrological regime and grazing management on ground beetles of Skealoghan turlough. Distinct ground beetle communities have been found associated with different hydrological regimes with carabid beetle community composition sensitive to both changes in hydrological regime and vegetation structure. The hydrological regime is the primary factor controlling the carabid species composition of this grazed wetland. Grazing, particularly selective grazing by animals plays an important but subordinate role to hydrology in providing suitable habitat conditions for many species of conservation importance. This paper provides a detailed assessment of species responses to wetland management and demonstrates the need to maintain a range of hydrological and grazing regimes.     

Persistence of high elevation fens in the Southern Rocky Mountains,on Grand Mesa,Colorado, U.S.A.

Small headwater fens at high elevations exist in the dry climatic regime of western Colorado, despite increasing demands for water development since the 1800’s. Fens on Grand Mesa have accumulated plant material as peat for thousands of years due to cold temperatures and consistently saturated soils. The peatlands maintain unique plant communities, wildlife habitat, biodiversity, and carbon storage. We located and differentiated 88 fens from 15 wet meadows and 2 marshes on Grand Mesa. Field work included determining vegetation, soils, moisture regimes, and impacts from human activities. All fens were groundwater-supported systems that occurred in depressions and slopes within sedimentary landslide and volcanic glacial till landscapes. Fens occupied 400 ha or less than 1 % of the 46,845 ha research area and ranged in size from 1 to 46 ha. Peat water pH in undisturbed sites ranged from 4.3 to 7.1. Most fens had plant communities dominated by sedges (Carex) with an understory of brown mosses. Variation in vegetation was controlled by stand wetness, water table level, organic C, conductivity (EC), and temperature °C. Fen soils ranged from 13.6 to 44.1 % organic C with a mean of 30.3 %. Species diversity in fens was restricted by cold short growing seasons, stressful anaerobic conditions, and disturbance. Multivariate analysis was used to analyze relationships between vegetation, environmental, and impact variables. Stand wetness, water table level, OC, electrical conductivity (EC), and temperature were used to analyze vegetation variance in undisturbed fens, wet meadows, and marshes. Vegetation composition in impacted fens was influenced by flooding, sedimentation, stand wetness, water table level, OC, EC, and temperature. Hydrologically modified fens supported 58 plant species compared to 101 species in undisturbed fens. Analysis of historical 1936–2007 aerial photographs and condition scalars helped quantify impacts of human activities in fens as well as vegetation changes. Fourteen fens had evidence of peat subsidence, from organic soil collapse, blocks of peat in the margins, soil instability, and differences in surface peat height between the fen soil surface and the annually flooded soil surface. Of 374 ha of fens in the Grand Mesa study area, 294 ha (79 %) have been impacted by human activities such as ditching, drainage, flooding, or vehicular rutting. Many fens had little restoration potential due to severe hydrological and peat mass impacts, water rights, or the cost of restoration.     

Humid grassland fallows promote spider diversity in a traditionally managed landscape

Agricultural intensification is an important driver of biodiversity decline. Regarding grassland ecosystems, traditionally managed hay meadows, as opposed to highly productive silage grassland, are often of high conservation value. Here, we compare spider assemblages among five grassland management regimes along an intensification gradient, ranging from long-term fallows (not farmed for ≥ 30 years) via traditionally managed hay meadows to high-intensity silage grassland. Humid long-term fallows harboured highest species richness and diversity, and their assemblages differed strongly from other management regimes. There was surprisingly little variation though among different types of hay meadows and silage grassland. We also included environmental parameters and land-cover types in the surroundings of study sites, indicating that spider assemblages were most strongly shaped by fallow-related parameters and the proportion of forests. The high spider diversity on fallows may result from their undisturbed vegetation structure, while management, regardless of frequency, may have detrimental effects. Our results demonstrate the high importance of unmanaged areas even in regions with an overall low land-use intensity, such as grassland ecosystems. We thus recommend the inclusion of temporal grassland fallows (unmanaged for 3-5 years) in agri-environmental schemes to increase landscape heterogeneity and preserve spider diversity.     

Habitat selection of the globally threatened Aquatic Warbler Acrocephalus paludicola at the western margin of its breeding range and implications for management

The globally threatened Aquatic Warbler Acrocephalus paludicola is an umbrella species for fen mires and is at risk of extinction in its westernmost breeding population due to severe habitat loss. We used boosted regression trees to model Aquatic Warbler habitat selection in order to make recommendations for effective management of the last remnant habitats. Habitat data were collected in the years 2004–2006 in all remaining breeding sites in Pomerania (eastern Germany and western Poland) as well as in recently abandoned sites. Models were validated using data from similar Aquatic Warbler habitats in Lithuania. The probability of occurrence of Aquatic Warblers in late May/early June was positively associated with low isolation from other occupied sites, less eutrophic conditions, a high proportion of area mown early in the preceding year, high availability of vegetation 60–70 cm high, high prey abundance and high habitat heterogeneity. Early summer land management is needed in the more productive sites to prevent habitat deterioration by succession to higher and denser vegetation. As this also poses a serious threat to broods, management that creates a mosaic of early and late used patches is recommended to preserve and restore productive Aquatic Warbler sites. In less productive sites, winter mowing can maintain suitable habitat conditions. Aquatic Warbler‐friendly land use supports a variety of other threatened plant and animal species typical of fens and sedge meadows and can meet the economic interests of local land users.     

Impact of rubber plantation on carabid beetle communities and species distribution in a changing tropical landscape (southern Yunnan, China)

Carabid beetles (Coleoptera: Carabidae) have widely been used to assess biodiversity values of different habitats in cultivated landscapes, but rarely in the humid tropics. This study aimed to investigate effects of land use change on the carabid assemblages in a tributary valley of the Mekong River in tropical southern Yunnan, China. The study area includes habitats of traditional land use systems (rice production and shifting cultivation successions) and was dominated by natural forests until about 30?years ago. Since then, large areas of forest have been, and still are, successively transformed into commercial rubber monoculture plantations. In total, 102 species of Carabidae (including Cicindelinae) were recorded from 13 sites over different seasons, using pitfall traps, Malaise traps and aerial collectors in trees. Cluster analysis and indicator species analysis showed that three types of habitat (rice field fallows, early natural successions and natural forest) possess a degree of uniqueness in species composition. Non-metric multidimensional scaling revealed that the environmental factors explaining 80% of the total variation in carabid assemblage composition are the degree of vegetational openness of a habitat and its plant species diversity. Rice field fallows had significantly higher numbers of species and individuals than any other type of habitat and are probably dominated by species originating from other regions. Carabid assemblages of young rubber plantations (5 and 8?years) were quantitatively similar to those of forests, but without species of significant indicator value. With increasing plantation age (20 and 40?years), the number of carabid species decreased. Increasing age and a further spatial expansion of rubber plantations at the expense of forest areas will have negative impacts on the native forest carabid assemblages with strongest effects on forest specialists and rare species.     

Mountain river restoration measures and their success(ion): Effects on river morphology,local species pool,and functional composition of three organism groups

We investigated temporal effects of restoration on river morphology, on species and functional composition of benthic invertebrates, floodplain vegetation and carabid beetles at three study sites in the mountain river Lahn (Germany). We sampled restored and nearby non-restored sections 3–5 years and 7–9 years after restoration. In the restored sections, instream microhabitat heterogeneity was higher due to the increased presence of finer substrates, while cobbles and coarse gravel were still dominant. Instream habitat composition did not change between the two sampling events. Areas of restored floodplain were characterized by a more diverse habitat mosaic and by unvegetated bars, vegetated islands and secondary channels. In restored sections, floodplain habitat heterogeneity was maintained 7–9 years after restoration, but vegetated areas increased, while unvegetated bars and aquatic areas decreased. The species composition of all studied groups was more variable over time in restored than non-restored sections. In contrast to benthic invertebrates, the immigration rate of floodplain vegetation and carabid beetle species was higher in restored sections. Assemblage composition of all three organism groups changed over time, with the highest change in carabid beetles and smallest in benthic invertebrates. Restoration changed the abundances of functional response groups, mainly for carabid beetles, by supporting species that indicate increased hydrodynamics and early successional stages. Changes of functional response groups in non-restored and restored sections across time indicated decreased hydrodynamics or hydrological connectivity for all organism groups. Although the response of organism groups differed, our results support the conjecture that restored sections accumulate species and enhance the local species pool.     

Taxon specific response of carabids (Coleoptera,Carabidae) and other soil invertebrate taxa on invasive plant Amorpha fruticosa in wetlands

False indigo (Amorpha fruticosa L.) is an invasive exotic plant introduced to Europe in the early eighteenth century. Its spread has been rapid, particularly in disturbed wetland habitats, where it forms dense impermeable monospecific stands and modifies habitat conditions. The impact of A. fruticosa on native plant communities has been well analyzed, however knowledge concerning the possible effects on soil invertebrates and particularly carabid beetles is completely lacking. This study analyzed the impact of an A. fruticosa invasion on carabid beetles and other soil invertebrates. Soil fauna was sampled by pitfall traps at natural habitats, initially colonized by A. fruticosa, and habitats largely invaded by A. fruticosa. In total 2,613 carabid beetles belonging to 50 species and 72,166 soil invertebrates were collected. The invasion of A. fruticosa strongly affected the carabid beetle species composition, which clearly differed between all studied sites. Widespread euritopic carabid beetle species showed positive responses to A. fruticosa invasion, while the activity density of open habitat species strongly declined. Mean individual biomass was significantly higher at invaded sites due to increased incidence of large carabids (genus Carabus Linné, 1758). Carabid beetle activity density and abundance of soil invertebrates were considerably higher at invaded sites than in natural sites. Conversely, the impact of A. fruticosa on carabid beetle species richness and diversity was less pronounced, most likely due to immigration from adjacent habitats. Changes in carabid beetle species composition and abundance of soil invertebrates were most likely due to changes in vegetation structure and microclimate. The results suggest that A. fruticosa invasion considerably affected carabid beetles, an insect group that is only indirectly related to plant composition. Therefore, severe future changes can be expected in invertebrate groups that are closely related to plant composition, since A. fruticosa cannot be completely removed from the habitat and covers relatively large areas.     

Importance of closed landfills as green space in urbanized areas: ecological assessment using carabid beetles

In a closed landfill, we investigated the diversity and ecological characters of carabid beetles to understand the ecological importance of closed landfills that have the potential as a multi-functional habitat for improving biodiversity in urbanized areas. In addition, we studied the influence of environmental factors (vegetation structure, soil) on distribution and diversity of carabid beetles. A total of 92,495 individuals representing 15 carabid species were collected from the closed landfill. Although the species richness of carabid beetles recorded in the closed landfill was not higher than the other green spaces in the city, the closed landfill could sufficiently provides a stable habitat as a semi-natural area for carabid beetles. Soil pH, Na, and tall grass plant cover influenced carabid assemblage in the closed landfill. However, other environmental variables (e.g., K⁺, Na⁺, Mg²⁺, bare land cover, weedy cover, and tree cover) were not correlated with carabid species composition. It is implied that in the closed landfill, which is a highly modified engineered environment, other abiotic environmental (e.g., drainage, soil texture, leachate, and landscape context, etc.) and biotic factors (e.g., intra- and interspecific competition) may have affected carabid assemblage. Although artificial drainages are essential facilities for landfill management, they are a critical factor that affects the species inhabiting the landfill. However, carabid beetles seemed to randomly fall into the artificial drainage. For successful management of closed landfills, it is very important that minimize the intervention and that develop the ecological sensitively management method.     

Effects of stream restorations on riparian mesohabitats,vegetation and carabid beetles

We investigated the effects of hydromorphological restoration measures (mainly the removal of bank fixations) on riparian mesohabitats, vegetation and carabid beetles by comparing 24 restored to nearby non-restored floodplain sections in Germany. Mesohabitats were recorded along ten equally-spaced transects, plant communities and riparian plant and carabid beetle species along three transects per section. Based on 18 indices including habitat and species diversity, taxonomic diversity and functional indices we compared the frequency and magnitude of changes following restoration, both for the overall dataset and for each site individually. Riparian habitat diversity doubled in restored sections compared to non-restored sections. The numbers of vegetation units and plant and carabid beetle species richness also doubled in restored sections, whereas changes in Shannon diversity were most pronounced for mesohabitats and riparian plants. Taxonomic diversity of carabid beetles decreased in restored sections reflecting post restoration dominance of riparian Bembidion species. Stress-tolerant pioneers of plant and especially carabid species benefit strongly from the re-establishment of open sand and gravel bars, while hygrophilous species, which also include non-riparian species, did not respond to restoration. We conclude that restoring river hydromorphology has almost generally positive effects on riparian habitats and riparian biodiversity. Riparian biota are thus well-suited indicators for the effects of hydromorphological restoration.     

Early effects of forest regeneration with selective and small scale clear-cutting on ground beetles (Coleoptera,Carabidae) in a Norway spruce stand in Southern Bavaria (Höglwald)

This study investigates the early effects of forest regeneration with selective, and small scale clear-cutting, on ground beetle (Coleoptera, Carabidae) community composition in a homogenous, mature spruce forest in Southern Bavaria (Höglwald), Germany. Carabid beetles were sampled with pitfall-, emergence-, and window-traps, from 1999 to 2001 during a pre-treatment year, the year of cutting, and the year after cutting. In the spruce stand we found a relatively low species richness with few dominating species. Selective cutting preserved this carabid assemblage. At the clear-cuts carabid species richness increased in the year of cutting, because of the invasion of small open field species, and the persistence of most forest species. Also, number of individuals increased due to higher numbers caught in the window-traps. The first open habitat species appeared just a few months after felling. However, in the next year the numbers of individuals, especially of forest species,were drastically reduced. Also, the number of species decreased, and was just slightly higher than on the control plot (mature stand). According to the DCA (detrended correspondence analysis) forest interior species had the same habitat preferences as net building spiders (Amaurobiidae, Linyphiidae) and other families of beetles (Staphylinidae, Curculionidae). Several groups of open habitat species responded positively on different patches found in the clear-cut: (1) diversity ofground vegetation, respectively coverage of shrubs, (2) favour for moist patterns, and water filled ruts (together with Gastropoda), or (3) low coverage of ground vegetation (together with free hunting spiders, Lycosidae). Different structures side by side (mature forest, selective cutting, open areas) may improve diversity on a forest scale. Small openings can serve as an important retreat for open habitat species. However, if clear-cuts become the dominant element, forest species maybe threatened. With selective cutting species richness of carabids is not improved; however, the remaining forest carabid species may be preserved during the early phase of the regeneration process.     

The effects of green tree retention and subsequent prescribed burning on ground beetles (Coleoptera: Carabidae) in boreal pine-dominated forests

We studied how two methods to promote biodiversity in managed forests, i.e. green tree retention and prescribed fire, affect the assemblages of carabid beetles. Our experiment consisted of 24 study sites, each 3–5 ha in size, which had been prepared according to factorial design. Each of the eight treatment combinations determined by the two factors explored – tree retention level (0, 10, 50 m³/ha^?1 and uncut controls) and prescribed use of fire (yes/no) – was replicated three times. We sampled carabids using pitfall traps one year after the treatments. Significantly more individuals were caught in most of the burned sites, but this difference was partially reflective of the trap‐catches of Pterostichus adstrictus. The fire did not increase no. of P. adstrictus in the uncut sites as much as in the other sites. Species richness was significantly affected by both factors, being higher in the burned than in the unburned sites and in the harvested than in the unharvested sites. Many species were concentrated in the groups of retention trees in the burned sites, but only a few were in the unburned sites. The species turnover was greater in the burned than in the unburned sites, as indicated by the NMDS ordinations. Greater numbers of smaller sized species and proportion of brachypterous species were present in the burned sites. Fire‐favored species, and also the majority of other species that prefer open habitats were more abundantly caught in the burned sites than in the unburned sites. Dead wood or logging waste around the traps did not correlate with the occurrence of species. We conclude that carabids are well adapted to disturbances, and that frequent use of prescribed fire is essential for the maintenance of natural assemblages of carabid beetles in the boreal forest. Small retention tree groups can not maintain assemblages of uncut forest, but they can be important by providing food, shelter and breeding sites for many species, particularly in the burned sites.     

Impact of environmental factors on the body shape variation and sexual shape dimorphism in Carabus granulatus L.(Coleoptera: Carabidae)

Despite plenty of data in insects shape variation,papers on environmental factors effect on such variation are scarce and in ground beetles are practically absent.The aim of this research was to:(i) model the effect of the region of habitation,urbanization and habitat vegetation into the shape variation in widespread carabid species;(ii) describe sexual shape dimorphism in studied species.Samples were pitfall trapped in different regions of its area in the spectrum of anthropogenic influence (cities,suburbs,natural biotopes).One thousand and one hundred sixty-eight specimens were analyzed for six morphometric traits and terminal points of those measurements were used as landmarks for Procrustes analysis.We used linear models to reveal which factor (region,urbanization or vegetation) and in what direction affected beetles shape.Results showed that males in C.granulatus had more convex elytra and head,and the more convex in apical-basal direction pronotum.In its area from the east to the west elytra flattened in medial-distal direction and pronotum flattened in apical-distal direction.In disturbed urban environment beetles pronotum became more convex in both sexes and males elytra became more convex too.In open habitats (meadows,lawns) beetles became more flattened.     

A field experiment on the effectiveness of spiders and carabid beetles as biocontrol agents in soybean

1 Spiders and carabid beetles are abundant generalist predators that prey upon insect pests of soybean. A field experiment was conducted to determine the impact of spiders and carabids on soybean yield. Prior to planting, three 7 × 7 m plots were fenced in order to reduce spider and carabid immigration. Carabids that emerged within the plots were not removed, but spiders that ballooned into these predator‐reduction plots or that entered by climbing the fence were removed by pitfall trapping and searching the vegetation. Three unmanipulated, unfenced plots served as the control treatment. 2 Densities of spiders on soybean vegetation, and activity‐densities of spiders and carabids determined by pitfall trapping, were c. 75% lower in the spider‐carabid reduction treatment than in control plots. Despite clear differences between treatments in numbers and activity of these major generalist predators, the weight of soybeans harvested did not differ between control and spider‐carabid reduction plots. 3 Paralleling the absence of an effect of predator reduction on soybean yield was the absence of any significant difference between treatments in densities of whiteflies (Aleyrodidae), leafhoppers (Cicadellidae), thrips (Thysanoptera), Lepidoptera larvae and herbivorous Coleoptera. 4 Our experiment provides no evidence that spiders and carabid beetles at ambient densities affect soybean yield. Low populations of pest species or low predation pressure on soybean pests by spiders and carabids at the ambient densities of this experiment could be responsible for this result.     

Forest edge contrasts have a predictable effect on the spatial distribution of carabid beetles in urban forests

Fragmented urban forest remnants are characterised by sharp edges and are bordered by various land-use types, which may have a considerable effect on the fauna and flora at forest edges, and into forest interiors. To investigate the effects of differentially contrasting edges (low vs. intermediate vs. high) on carabid beetle assemblages in urban boreal forests, we placed pitfall traps along a gradient from 6?m into three matrix types (secondary forest vs. grassland vs. asphalt) up to 60?m into urban forest patches in the cities of Vantaa and Helsinki, southern Finland. Individual species and carabid beetle assemblages were strongly affected by edge contrasts and distance from the forest edge. The strongest effect on individual species was caused by high contrasting edges: generalist and open-habitat species were favoured or not affected while forest specialists were affected negatively. Effects of the abundances of potential prey and competitors on the carabid beetles were also evaluated. Forest and moisture-associated carabid species were negatively to neutrally associated with springtail abundances while generalist and open habitat, and dryness associated species were more positively related to springtail abundances (a potential food source). In terms of potential competitors, forest and moisture-associated carabid species were negatively and/or neutrally affected by ant and wood ant numbers, while generalist and open-habitat species were neutrally to positively associated with these taxa. It appears that carabid beetle habitat associations are more important in the responses of these beetles across edges of different contrast than are the prey and competitor numbers collected there. We recommend the creation of “soft” or low-contrast urban edges if the aim of urban management is to protect forest carabids in cities.     

The impact of maize-bean intercropping on insect biodiversity

Intensive agriculture is one of the main reasons for recent insect declines. This loss of biodiversity has created the need to develop methods of intensive cultivation that combine high yields with biodiversity conservation. One promising method in maize cultivation is intercropping with beans. The objective of this study was to determine whether maize-bean intercropping could increase insect biodiversity. We examined the activity density, species richness and Shannon diversity of bees and carabid beetles in pure and intercropped maize under both organic and conventional management. We collected carabid beetles using pitfall traps and bees by doing transect walks. The study was carried out in an agricultural landscape, on a set of 17 study sites. We found that intercropping leads to significant increases in bumblebee and honeybee activity as well as in bee species richness. Differences between pure and intercropped maize were dependent on the year of data acquisition and the management style. Solitary wild bee species activity was not significantly affected. Carabid activity density and carabid species richness also did not differ significantly between the cropping systems. We conclude that maize-bean intercropping can contribute to insect biodiversity conservation but its contribution is limited to bumblebees. Despite its relatively low contribution per hectare, maize-bean intercropping could have a surprisingly positive impact, as maize now covers large areas of German farmland. Potential exists to increase the biodiversity value of maize intercropping even further by using varied plant mixes. Our results strongly encourage further research in this direction.     

Regional hotspots of butterfly diversity in a protected area: Are they indicators of unique assemblages and areas with more species of conservation concern?

The implementation of biodiversity studies to set conservation priorities assumes that the different criteria used in prioritisation are correlated. Based on butterfly data, we examined whether high total diversity (species density and richness), unique species assemblages, and high numbers of different categories of Species of European Conservation Concern (SPEC) were co-located in the same habitats in the Picos de Europa National Park, Spain. Species density (number of species per sample) declined with elevation and was significantly higher in Genista shrublands on southern slopes (Southern Genista shrubland). We found unique species assemblages for Southern Genista shrublands, heathlands, mown meadows and subalpine meadows, whereas Genista shrubland on northern slopes (Northern Genista shrubland) and pastures were occupied by more habitat generalist species. We also found an effect of elevation on species composition. Species with global distributions concentrated in Europe (SPECs 4b) tended to be associated with Southern Genista shrubland, whereas species with global distributions restricted to Europe (SPECs 4a) were associated with higher elevations. Thus, we suggest a higher conservation value for butterfly assemblages located both on Southern Genista shrublands and at high elevations as they contain unique assemblages with a higher number of SPECs. By comparing our data with a previous study on carabid beetles, we found a low coincidence between butterflies and beetles for habitats with high species diversity and unique assemblages. Our study suggests that preserving areas in the landscape supporting higher butterfly diversity only partially preserves those species of greater conservation concern, and that butterflies cannot be used as a reliable indicator of other priority taxa for conservation, such as carabid beetles.