Species Richness Of Carabid Beetles Research Articles

Species Enriched Grass–Clover Pastures Show Distinct Carabid Assemblages and Enhance Endangered Species of Carabid Beetles (Coleoptera: Carabidae) Compared to Continuous Maize

There is an urgent global need for the ecological intensification of agricultural systems to reduce negative impacts on the environment while meeting the rising demand for agricultural products. Enriching grasslands with floral species is a tool to promote diversity and the associated services at higher trophic levels, and ultimately, to enhance the agricultural landscape matrix. Here, we studied an organic pastures-based dairy production system with plant species enhanced grass–clover pastures with respect to the effect on the activity density, functional traits, carabid assemblages, and species richness of carabid beetles. To understand the effect of land management on carabid beetles, we studied two types of grass–clover pastures with low and relatively high plant diversities in an integrated crop–livestock rotational grazing system (ICLS). As a comparison, organic permanent grasslands and conventionally managed maize were studied. We installed pitfall traps for three weeks in early summer, and for two weeks in autumn. In total, 11,347 carabid beetles of 66 species were caught. Grass–clover pastures did not differ in activity density, functional traits, habitat guilds, or species richness, but conventional maize did show a higher activity density in autumn and a higher proportion of eurytopic species and mobile species compared to grass–clover pastures. On grass–clover pastures, we found more endangered species, Carabus beetles, and a distinct carabid assemblage compared to maize. However, we attribute the lack of an effect of increased plant diversity of the grass–clover pastures on carabid species richness and functional traits to the intensive grazing regime, which resulted in the compositional and structural homogeneity of vegetation. Still, the presence of specialized and endangered species indicated the potential for organically managed grass–clover pastures to promote dispersal through an otherwise depleted and fragmented agricultural landscape. By increasing crop diversity in ICLS, more resources for foraging and nesting are created; therefore, organically managed grass–clover pastures add to the multi-functionality of agricultural landscapes.

Conservation value of traditional meadow irrigation for carabid beetles

Locally adapted and evidence-based management strategies are needed to counteract the current insect declines. In Central Europe, semi-natural grasslands are biodiversity hotspots having a high conservation value, but are threatened by both abandonment and agricultural intensification. We investigated the potential of traditional lowland meadow irrigation as a biodiversity-friendly grassland management strategy using carabid beetles as indicator organisms. We analysed carabid beetle species richness, the occurrence of species of conservation concern, and trait composition in relation to meadow irrigation and fertilization. Moreover, we conducted bipartite network analysis in order to reveal species-habitat networks. The key finding is that the species richness of carabid beetles in irrigated and non-irrigated meadows was similar, but irrigation positively influenced species and individual numbers of carabids of conservation concern. Meadow irrigation, but also fertilization, further shaped carabid beetle species-habitat-networks indicating species-specific preferences for differently managed meadows. Finally, the trait composition was affected: carabid beetles in irrigated meadows were on average larger, more predacious and less mobile than in non-irrigated meadows. We therefore recommend the preservation and restoration of this traditional grassland management practice for biodiversity conservation in suitable regions, but also call for future studies to further increase conservation evidence.

The response of plants, carabid beetles and birds to 30 years of native reforestation in the Scottish Highlands

Abstract Globally, there is increasing interest in tree planting, leading to many country‐level commitments to reforestation. In the UK, current commitments would achieve 17% forest cover by 2050, with the highest rates of forest expansion expected in Scotland. Forest expansion with native trees is expected to increase biodiversity, particularly woodland specialist species, and associated ecosystem services. Despite this, data on biodiversity changes over the early stages of reforestation are sparse, particularly for upland areas in Scotland where opportunities for forest expansion are greatest. We collected data on the response of plants, carabid beetles and birds to native reforestation and grazing exclusion, using sites reforested over the last 30 years in the Scottish Highlands. Biodiversity in ungrazed, reforested sites was compared to unforested controls and mature native forest, both grazed and ungrazed. Mean bird species richness in reforested plots (4.4 [95% CI: 3.2, 5.9]) was higher than in unforested plots (0.8 [0.5, 1.3]), but lower than in mature forest plots (7.0 [5.4, 8.3]). In contrast, there was no systematic difference in plant or carabid beetle species richness in reforested, unforested or mature forest plots, or between grazed and ungrazed plots for the species richness of any groups. Woodland specialist bird and plant species were found in the reforested plots, and richness of woodland specialist bird species was predicted to reach levels in mature forest c. 36 years after reforestation. Species assemblages differed across habitat categories. For birds and plants, species assemblages in reforested sites were intermediate to unforested and mature sites. For carabid beetles, the assemblages in mature and reforested sites were comparable and differed from unforested sites. Grazing did not strongly influence species assemblages. Policy implications. We show that woodland specialists colonise reforested sites and species assemblages transition towards those found in the target habitat within the first 30 years of reforestation with native species. Native forest should be prioritised in Scotland's future forest expansion targets, given that mature native forest is scarce and fragmented in the Scottish Highlands and that the ultimate gain from native forest expansion may accrue over long time‐scales.

Effects of Strip Tillage in Sugar Beet on Density and Richness of Predatory Arthropods.

Strip tillage, in which tillage and seedbed preparation are limited to a narrow band where the subsequent crop is planted, provides many potential agronomic benefits, including reduced fuel and labor costs, reduced erosion, and improved soil tilth. Lower soil disturbance and enhanced water retention associated with strip tillage also may affect density and diversity of predatory arthropods, which have been little studied in sugar beet. We examined the effects of tillage (conventional versus strip) on the predatory epigeal arthropod fauna in sugar beet. Studies were conducted over three growing seasons (2010-2012) in Idaho using both fenced and unfenced pitfall traps to sample arthropods. Unfenced pitfall traps often captured a greater activity density and richness of predators, and showed no bias of higher captures in conventionally tilled plots as has been shown elsewhere. Total density of predators was higher in strip tillage only during 2011. Density and species richness of carabid beetles did not differ between tillage treatments during the course of the study. Density of the other major taxa (staphylinid beetles, spiders, and Opiliones) was higher under strip tillage during some years, especially early in the season, but richness showed little or no relationship with tillage. Predaceous arthropods might be favored by enhanced ground cover, higher humidity, more moderate temperatures, and/or less habitat disturbance associated with strip-tilled plots. The results suggest that certain groups of soil-dwelling predatory arthropods can be favored by strip tillage in sugar beet, which further adds to the benefits of conservation tillage in this system.

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

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

English

Tropical forest soils have potential to mitigate climate change and support biodiversity. Human activities in these forests threaten biodiversity and alter the ability of the soil to sequester carbon. Many tropical countries experience rampant anthropogenic activities in the forests, yet the extent to which these activities affect biodiversity and soil organic carbon and the relationship between the two is not well studied. In this study, the correlation of soil organic carbon (SOC) and ground beetles was assessed in both control and disturbed sites in Uzungwa Scarp Nature Reserve (USNR). Disturbance activities included logging for timber, tool handles and building poles; fire, hunting, footpaths, collection of fuel wood, and clearing for agriculture. Pitfall trapping, active searching during the day, and active night searching were methods used to collect the ground beetles. Soil samples were collected at three depths 0-15, 15-30 and 30-45 cm in twelve plots: six in disturbed and six in control sites. A total of 890 ground beetles comprising 30 species were collected. The species richness of carabid beetles was high in the control sites (26 species) and low in disturbed site (16 species), with the respective Shannon-Wiener being Hꞌ= 2.103 and Hꞌ = 1.327. The difference in species diversity was statistically significant. Abundance of carabid beetles was also significantly higher in control sites compared to disturbed sites. Mean SOC was low in disturbed sites and high in control sites at all three depths. In disturbed sites, the correlation between SOC and species richness was weakly negative but not significant, and positively correlated with abundance, though it was not statistically significant. In control sites, there was a significant positive correlation between SOC and carabid abundance, but not with species richness of carabid beetles. To conclude, protection of natural forests is prerequisite for biodiversity and ecosystem services. We recommend that management improvement is urgently required, because ongoing human activities seem to contribute to diminished SOC stock.   Key words: Soil organic carbon, disturbance, ground beetles, correlation.

Are power-line corridors an alternative habitat for carabid beetle (Coleoptera: Carabidae) and wolf spider (Araneae: Lycosidae) heathland specialists?

Semi-natural habitats such as heathlands, are important for the conservation of biodiversity. Due to a significant decline in traditional management, e.g. burning and grazing, in combination with habitat loss, these ecosystems have become highly threatened. On the other hand, human activities create modern infrastructures, e.g. power-line corridors (PLCs), and they can function as an alternative habitat for species for which their semi-natural habitat has degraded. This study compared the species richness and species composition of carabid beetles and wolf spiders in PLCs, traditionally managed heathlands and former heathlands that are covered with coniferous forests. We also measured vegetation variables and used it to compare species richness of plant, abundances of species and Ellenberg indicator values in the different habitats. The results showed that species richness of carabid beetles in the traditionally managed heathland is significantly higher compared to the PLCs. The species composition of carabid beetles and wolf spiders were also significantly different in these two habitats, but there was no difference between the species composition of carabid beetles and wolf spiders in the PLCs and forests. This might be explained by the similar vegetation structure in the PLCs and the forests, such as the high abundance of trees and shrubs and low abundance of typical heathland plants. Our results showed that PLCs are not an alternative habitat for the carabid beetle and wolf spider heathland specialists. We discussed how the management could be changed in the PLCs in order to make them more valuable for these and other heathland species.

A comparison of diversity and composition of carabid beetles between overpasses and underpasses in fragmented forest areas

Wildlife crossing structures are important for increasing biodiversity of wildlife and other animals. Thus, the objective of this study was to compare the community structure of carabid beetles along environmental transects of forest–edge–crossing structures in fragmented forest areas. In addition, we also investigated whether there were differences in carabid beetle assemblages due to structural differences in crossing structures, i.e., overpass and underpass. A total of 3,737 carabid beetles belonging to 60 species were collected by pitfall trapping across environmental transects from June 6 to September 3, 2015. In crossing structures, environmental variables, such as soil texture, soil organic matters, and habitat structures were different from those in neighboring habitats. Abundance and species richness of carabid beetles in underpasses were significantly lower than those in neighboring habitats and overpasses. In particular, underpasses, especially those with more artificial structures in terms of soil properties and microhabitat, appeared to be less appropriate structures for movement of carabid beetles. Although less carabid beetle species were caught in crossing structures, species composition of carabid beetles were more similar to forest areas. In conclusion, efforts are needed to improve the connectivity of habitats and consider the needs of invertebrates by providing suitable microhabitats for wildlife crossing structures.

Even the smallest non-crop habitat islands could be beneficial: distribution of carabid beetles and spiders in agricultural landscape.

Carabid beetles and ground-dwelling spiders inhabiting agroecosystems are beneficial organisms with a potential to control pest species. Intensification of agricultural management and reduction of areas covered by non-crop vegetation during recent decades in some areas has led to many potentially serious environmental problems including a decline in the diversity and abundance of beneficial arthropods in agricultural landscapes. This study investigated carabid beetle and spider assemblages in non-crop habitat islands of various sizes (50 to 18,000 square metres) within one large field, as well as the arable land within the field, using pitfall traps in two consecutive sampling periods (spring to early summer and peak summer). The non-crop habitat islands situated inside arable land hosted many unique ground-dwelling arthropod species that were not present within the surrounding arable land. Even the smallest non-crop habitat islands with areas of tens of square metres were inhabited by assemblages substantially different from these inhabiting arable land and thus enhanced the biodiversity of agricultural landscapes. The non-crop habitat area substantially affected the activity density, recorded species richness and recorded species composition of carabid and ground-dwelling spider assemblages; however, the effects were weakened when species specialised to non-crop habitats species were analysed separately. Interestingly, recorded species richness of spiders increased with non-crop habitat area, whereas recorded species richness of carabid beetles exhibited an opposite trend. There was substantial temporal variation in the spatial distribution of ground-dwelling arthropods, and contrasting patterns were observed for particular taxa (carabid beetles and spiders). In general, local environmental conditions (i.e., non-crop habitat island tree cover, shrub cover, grass cover and litter depth) were better determinants of arthropod assemblages than non-crop habitat island size, indicating that the creation of quite small but diversified (e.g., differing in vegetation cover) non-crop habitat islands could be the most efficient tool for the maintenance and enhancement of diversity of ground-dwelling carabids and spiders in agricultural landscapes.

Effect of boundary type and season on predatory arthropods associated with field margins on New Zealand farmland

Pitfall traps were used to monitor predatory arthropod numbers along two types of field boundary, a post and wire fence line and a Cupressus macrocarpa hedge, along the same paddock margin in Canterbury, New Zealand, over 24 months. The seven most abundant predator groups recorded were: Araneae > Phalangiidae > Staphylinidae > Coccinellidae > Chilopoda > Hemerobiidae > Carabidae. Araneae, Phalangiidae, Staphylinidae, Chilopoda and Hemerobiidae were found in larger numbers at the wire fence than at the hedge site, whereas the numbers of Carabidae and Coccinellidae adults exhibited no field margin preference. However, more species of Araneae and Staphylinidae were caught at the hedge site, whereas species richness of carabid beetles was greatest at the wire fence. Principal component analysis clearly separated the samples collected from the two habitats based on the assemblages of Araneae, Staphylinidae and Carabidae, and certain species in each of these taxonomic groups appeared to be particularly associated with one boundary type or the other. All the main taxonomic groups exhibited clear seasonal patterns, with distinct peaks in abundance occurring at certain times of the year. The results of the study reinforce the idea that management of field boundaries can be used to manipulate the type and abundance of particular groups of predatory arthropods, and that seasonal patterns should be taken into account in schemes of integrated pest management so that any adverse effects of biocide application on these beneficial species may be minimised.

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 Linne, 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 agri-environment management for cirl buntings on other biodiversity

Agri-environment scheme (AES) management has increased populations of cirl buntings (Emberiza cirlus) in South Devon, England, and might be expected to provide benefits for other declining biodiversity, due to less intensive farm management. Fields managed under AES for cirl buntings (low-input spring barley or permanent pasture without inputs) were contrasted with control fields under conventional management (spring barley without management restrictions and winter cereals, or grazed without management restrictions) to identify such benefits for vascular plants, butterflies, bumblebees, carabid beetles, foliar invertebrates and bats. Activity-density and species richness of carabid beetles were both higher in AES spring barley fields than in control spring barley and winter cereal fields. Forb cover and abundance of butterflies and bumblebees were higher in AES spring barley fields than in winter cereals, but did not differ between AES and control spring barley. No difference was observed in plant species richness between any of the arable field types. Plant species richness and butterfly abundance were higher in AES pasture fields than in controls. Abundance, activity-density and/or species richness of other taxa did not differ between AES and control pastures. Benefits observed in AES spring barley fields arise from management specific to AES agreements, and also, we suggest, from the maintenance of spring-sown barley in the landscape. Benefits in AES pasture fields are ascribed to the absence of fertiliser and pesticide inputs, and reductions in stocking arising from this; there is also likely to have been some pre-selection for older pastures to be entered into AES management agreements. Agri-environment measures for cirl buntings have benefits for a range of taxa beyond the target species, and therefore, largely through reduction of management intensity and maintenance of land-use diversity, improve the overall biodiversity of the farmed landscape where they are present.

Arable weeds in organically managed wheat fields foster carabid beetles by resource- and structure-mediated effects

Arable weeds in organically managed fields may foster arthropod generalist predators by the provision of shelter and favorable microclimate (structure-mediated effects) and the provision of additional animal and floral food resources (resource-mediated effects). In three organically managed winter wheat fields in Central Germany, we investigated the impact of weed removal and introduction of artificial weed-like structure on the activity density and species richness of carabid beetles with respect to trophic groups, microclimatic conditions, and densities of potential prey. Removal of weeds reduced both carabid activity density and species richness but did not affect trophic group composition. The decline in carabid activity density was dampened by the addition of artificial structure. Mean daily surface temperature and light intensity were significantly lower under weeds and artificial plants than under wheat plants alone. Weed removal reduced the abundance of leafhoppers and true bugs, but the response was inconsistent across fields. We conclude that the presence of arable weeds in organically managed wheat fields fosters carabid activity density and species richness via resource-mediated effects, such as a higher availability of weed-borne resources (e.g. seeds and pollen) and herbivorous prey. Structure-mediated effects (altering the microclimate) add to this positive effect. The presence of weeds in organically managed wheat fields enhances carabid activity density and diversity and needs to be integrated into future management strategies for natural enemy conservation.

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.

An assessment of methods for sampling carabid beetles (Coleptera: Carabidae) in a montane rain forest

Pitfall trapping is the traditional method for sampling carabid beetles and other grounddwelling invertebrates. Tests were carried out in the Udzungwa Mountains National Park between March 1999 and July 2000. Results indicated that pitfall traps were less efficient compared to manual searching methods, both in terms of relative abundance and species richness of carabid beetles. The results are discussed in the context of biodiversity inventories in theEastern Arc Mountains.

Staphylinidae and Carabidae overwintering in wheat and sown wildflower areas of different age.

Species richness and abundance of staphylinid and carabid beetles overwintering in winter wheat fields and 1- to 3-year-old wildflower areas were investigated during 2000/2001 on 16 study sites in Switzerland. Abundance and species richness of overwintering staphylinids significantly increased with successional age of the wildflower areas and were always higher in older wildflower areas than in winter wheat. A similar but less distinct pattern was observed for the abundance and species richness of carabid beetles. The influence of habitat parameters (vegetation cover, fine sand content, organic matter, pH, soil pore volume, surrounding landscape structure, habitat area) on the staphylinid and carabid assemblages based on the number of individuals per species and site was analysed using canonical correspondence analysis. Vegetation cover was the most significant parameter significantly characterizing both staphylinid and carabid assemblages. The amount of vegetation cover explained 15.7% of the variance, fine sand content accounted for 13.3% and surrounding landscape structure for 10.9% of the variance in the staphylinid assemblage. In the carabid assemblage, vegetation cover was the only significant factor, explaining 24.7% of the variance. This study showed for the first time that the significance of wildflower areas as a reservoir for hibernation for generalist predatory beetles increases with progressing successional age.

Convergence in Arthropod Assemblages with Various Restoration Approaches for Canadian Deciduous Forests

Silvicultural practices are traditionally aimed at increasing forest profits; however, recent approaches to forest conservation have broadened to include nature-based silviculture for regenerating forests. In southern Ontario (Canada), originally dominated by deciduous forests, conifer plantations were established on abandoned agricultural sites. Currently, there is an increasing interest to convert these conifer stands to a state that mimics the original deciduous forest. We investigated arthropod abundance, species richness of carabid beetles, and abundance of arthropod assemblages (trophic and prey groups) under five silvicultural treatments conducted to regenerate deciduous forests (the natural forest type) from the old conifer plantations. The treatments included: (1) uniform canopy removal; (2) uniform canopy removal and understory removal; (3) group canopy removal; (4) group canopy removal and understory removal; and (5) untreated control plots (relatively pure red pine). Insects were sampled annually using sweepnets and pitfall traps. Results revealed treatment effects on the abundance of Coleoptera, Heteroptera, herbivores, and small arthropods (<3 mm) caught in sweepnet samples, where plots subjected to group shelterwood removal and understory removal supported higher abundances than the control plots. There was no treatment effect on the abundance of other arthropod groups or on the species richness and abundance of carabid beetles. The silvicultural treatments used to encourage natural regeneration did not seem to affect arthropod food availability for insectivorous vertebrates. Thus, the type of silvicultural strategy used to convert pine plantations to a stage that mimics the natural deciduous forests had little overall impact on arthropods.

Differences in ground beetles (Coleoptera: Carabidae) of original and reconstructed tallgrass prairies in northeastern Iowa, USA, and impact of 3-year spring burn cycles

Ground beetle assemblages were monitored at four tallgrass prairie sites burned on 3-year cycles in northeastern Iowa. The objectives of this study were to quantify differences in carabid communities between original and reconstructed tallgrass prairies, and to determine the responses of ground beetles to 3-year cycles of early spring fire commonly used to manage tallgrass prairies. Using pitfall traps, ground beetle assemblages in two original and two reconstructed tallgrass prairies were compared between 1994 and 1998, where beetles were sampled annually (0-, 1-, and 2-year post-fire conditions) from plots burned every 3 years. When burned, the greatest abundance, activity density, and species richness of carabid beetles occurred the year immediately following a spring burn, with abundance declining steadily with increased time since burning. Overall ground beetle diversity as determined by Shannon's diversity index was greatest in original tallgrass prairies several years after a fire. Some species of ground beetles were found only in original prairies, while others were found primarily in reconstructed prairie. Similarly, some species were more abundant the year immediately following a burn, while others were found in greater abundance with increased time since fire. NMS ordination and indicator species analysis clearly show differences in carabid species between original and reconstructed tallgrass prairies, but did not show differences among burn treatments.

Estimating species richness of pitfall catches by non-parametric estimators

Summary In consequence of accelerated applications of new land-use systems, agricultural landscape research is challenged to provide results on their sustainability. Studies on biodiversity that are carried out with minimal sampling programs have become increasingly popular. However, concerning insects, the observed number of species in these studies underestimates the true species richness. In such studies, the non-parametric estimators might provide a more reliable tool to gain information about the true species richness. The objective of this paper is to evaluate how accurately and precisely estimates of species richness in studies with few pitfall samples correlate with those of studies with higher sampling intensity. This indicates how much effort could be saved in collecting data on species richness of insect communities. The species richness of carabid beetles at ten temporary wetlands in the East-German agricultural landscape was surveyed by nine pitfall traps per site. Estimates of species richness were calculated in scenarios with four, five or six pitfall traps per site. The observed number of species and the non-parametric estimators, Chao2, Bootstrap, Jacknife1 and Jacknife2, were included in the study to estimate species richness in each scenario, respectively. The estimates in the scenarios were compared with estimations based on the whole data set. While Chao2 was the most accurate and precise estimator, the Bootstrap estimator performed only slightly better than the number of observed species. Jacknife1 and 2 performed intermediately. Only Chao2 performed more precisely than the observed number of species. In conclusion, the number of samples might be reduced to five or six pitfall traps per site in studies carried out in small habitats with minimal sampling programs. The non-parametric estimators provide possibilities to carry out studies on species richness with reduced sampling efforts as well as, to gain more reliable information on species richness re-analyzing studies already carried out.