Carabid Beetle Species Research Articles

Павуки і туруни як складові різноманіття членистоногих (Arthropoda) екосистем Льва-Ствизького Межиріччя (Рівненська область)

The series of epigeibiontic Arthropoda communities are investigated in several fo­rest and woodland ecosystems of Lva-Stvyga inter-river area within Volyn Polissia region of Ukraine. This is remoted district with peculiar ecological features as well as dominancy of oligotrophic forest and peat-bog ecosystems. The material of epigeibiontic arthropods was collected in spring and summer 2015 by the method of Barber’s pitfall traps. There are three pilot areas explored: 1) wet oligotrophic pine woodland (Ledo-Pinion); 2) late secondary succession of wet oligotrophic pine woodland cutting area; 3) dry oligotrophic pine woodland on the sands (Dicrano-Pinion). In total, 186 species of epigeibiontic arthropods were explored. There were found 75 species of spiders (Araneae) and 27 species of ground beetles (Coleoptera, Carabidae) among them. Along with that, the ants (Formicidae) have dominancy within related communities with an amount about 82–87 % of total arthropod individual’s number, and Araneae both with Carabidae exceed 6–7 % of this number. Nevertheless, there are nine spider species found for the first time for Ukrainian Polissia region and 1 species – Gnaphosa nigerrima – for the territory of Ukraine. One Carabid beetle species (Cymindis vaporariorum) was found at the first time for West Polissia region of Ukraine. There is also a number of rare and less known Araneae and Carabidae species found. Thus, the species composition and structure of explored Araneae & Carabidae communities show many specific features, which are caused by characteristic ecological and biogeographical peculiarities of oligotrophic ecosystems within investigated area. Following research of related taxonomical groups has to be directed to the wider spectrum of ecosystems covering, especially to peat-bog and mire complexes as unique protected habitats in Ukraine and the European Union.

Assessment of the Biological Control Potential of Common Carabid Beetle Species for Autumn- and Winter-Active Pests (Gastropoda, Lepidoptera, Diptera: Tipulidae) in Annual Ryegrass in Western Oregon.

Simple SummaryMany studies have shown that ground beetles feed on different agricultural pests, but little is known about their species communities from US cropping systems. We assessed the biological control potential of the most common carabid beetle species in Oregon annual ryegrass grown for seed by investigating spatial and temporal overlap of the most common species with those of the most damaging autumn- and winter-active pests (slugs, caterpillars and cranefly larvae) and determined the number of field-collected specimens that had fed on the respective pests using molecular gut content analysis. Only the non-native Nebria brevicollis was abundant during pest emergence and tested positive for all three pest groups. While the other common carabid beetle species—Agonum muelleri, Calosoma cancellatum and Poecilus laetulus—were also found to have consumed pests, they were active only during spring and summer, when crop damage by pests is less critical. We also show that disk tilling did not affect any of the four common carabid beetle species and that only N. brevicollis was significantly associated with a vegetated field margin. This study contributes to expanding our knowledge on conservation biological control in a system where chemical pesticides are still the mainstay of control against invertebrate pests.While carabid beetles have been shown to feed on a variety of crop pests, little is known about their species assemblages in US annual ryegrass crops, where invertebrate pests, particularly slugs, lepidopteran larvae and craneflies, incur major financial costs. This study assesses the biological control potential of carabid beetles for autumn- and winter-active pests in annual ryegrass grown for seed by: (a) investigating the spatial and temporal overlap of carabids with key pests; and (b) molecular gut content analysis using qPCR. Introduced Nebria brevicollis was the only common carabid that was active during pest emergence in autumn, with 18.6% and 8.3% of N. brevicollis collected between September and October testing positive for lepidopteran and cranefly DNA, respectively, but only 1.7% testing positive for slug DNA. While pest DNA was also detected in the guts of the other common carabid species—Agonum muelleri, Calosoma cancellatum and Poecilus laetulus—these were active only during spring and summer, when crop damage by pests is less critical. None of the four carabid species was affected by disk tilling and only N. brevicollis was significantly associated with a vegetated field margin. However, as its impact on native ecosystems is unknown, we do not recommend managing for this species.

A new perspective on the static metabolic allometry of carabid beetles.

The conventional allometric method entails fitting a straight line to logarithmic transformations of the original bivariate data and then back-transforming the resulting equation (at least implicitly) to form a two-parameter power function, Y = a × Xb , on the arithmetic scale. Although the protocol is widely used in contemporary research, it commonly performs poorly and thereby leads investigators to form inaccurate impressions of the dominant pattern in their data. Here I re-examine the metabolic allometry for six species of carabid beetle to illustrate the problem that arises when pattern in the original data can be described by two (or more) statistically equivalent equations with different functional form. Whereas conventional analyses of data for the beetles yielded only a single descriptive model for each dataset (i.e., the two-parameter power equation), the more versatile protocol used here fitted two to four statistically equivalent equations (including the two-parameter power function) to the same sets of observations. Conclusions based on just the power equation estimated by conventional allometry would be misleading because the equation does not afford a unique description for pattern in the data.

When the Ice Has Gone: Colonisation of Equatorial Glacier Forelands by Ground Beetles (Coleoptera: Carabidae).

Ground beetles (Coleoptera: Carabidae) are among the early colonisers of recently deglaciated terrains. While patterns of carabid colonisation along forelands of retreating glaciers have been thoroughly investigated in temperate climates, information remains scarce in tropical mountains. This study aimed to describe for the first time the carabid beetle species assemblages along the chronosequence of two tropical Andean glaciers (Antisana and Carihuairazo, Ecuador). Shannon index, taxonomic distinctness and species assemblage composition did not reveal deterministic and directional patterns. Only the principal coordinate analysis performed on the Antisana dataset showed that some species had a clear preference for terrains deglaciated for more than 200years. Our results showed that equatorial glacier forelands are colonised by pioneer species that persist from the recently deglaciated terrains (less than 25years) to terrains deglaciated since more than 200years. This pattern fits the 'addition and persistence model' of high-latitude glacier forelands, rather than the 'species replacement model' of the Alps. The pioneer species observed are high-altitude specialists adapted to constantly cold environments, but not specifically ice-related. In the current context of climate warming, pioneer and cold-adapted species living near the glaciers of equatorial mountains are therefore only threatened by the 'summit trap' risk, unlike in temperate regions, as they are not strictly linked to the glacier microclimate.

The origin of urban communities: From the regional species pool to community assemblages in city

AbstractAimCities worldwide are characterized by unique human stressors that filter species based on their traits, potentially leading to biodiversity loss. The knowledge of which species are filtered and at which scale is important to gain a more mechanistic understanding of urban community assembly and to develop strategies to manage human impact on urban ecosystems. We investigate the ecological mechanisms shaping urban community assembly, taking into account changes across scales, taxa and urban green space types.LocationCity of Zurich, Switzerland.TaxonCarabid beetles and wild bees.MethodsWe use a large species occurrence and trait dataset with a high spatial resolution to assess the filtering effect of a medium‐sized city on a regional pool of potential colonists. We then assess the filtering from the urban pool to five widely distributed types of urban green spaces.ResultsWe found that our model city selects for functionally similar but taxonomically diverse bee and carabid beetle species from the regional species pool. Within the city, community assembly processes vary among green space types and taxa resulting in important changes in community taxonomic and functional composition.Main conclusionsOur findings suggest that urban community assembly is a multi‐scale process dominated by the strong environmental filtering from a regional to an urban species pool. This leads to the selection of species pre‐adapted to urban conditions. Spatial habitat heterogeneity within and among UGS types can maintain an important taxonomic diversity within cities. However, increasing urban functional diversity would require stronger management efforts that consider regional ecological processes.

Species-level image classification with convolutional neural network enables insect identification from habitus images.

Changes in insect biomass, abundance, and diversity are challenging to track at sufficient spatial, temporal, and taxonomic resolution. Camera traps can capture habitus images of ground‐dwelling insects. However, currently sampling involves manually detecting and identifying specimens. Here, we test whether a convolutional neural network (CNN) can classify habitus images of ground beetles to species level, and estimate how correct classification relates to body size, number of species inside genera, and species identity.We created an image database of 65,841 museum specimens comprising 361 carabid beetle species from the British Isles and fine‐tuned the parameters of a pretrained CNN from a training dataset. By summing up class confidence values within genus, tribe, and subfamily and setting a confidence threshold, we trade‐off between classification accuracy, precision, and recall and taxonomic resolution.The CNN classified 51.9% of 19,164 test images correctly to species level and 74.9% to genus level. Average classification recall on species level was 50.7%. Applying a threshold of 0.5 increased the average classification recall to 74.6% at the expense of taxonomic resolution. Higher top value from the output layer and larger sized species were more often classified correctly, as were images of species in genera with few species.Fine‐tuning enabled us to classify images with a high mean recall for the whole test dataset to species or higher taxonomic levels, however, with high variability. This indicates that some species are more difficult to identify because of properties such as their body size or the number of related species.Together, species‐level image classification of arthropods from museum collections and ecological monitoring can substantially increase the amount of occurrence data that can feasibly be collected. These tools thus provide new opportunities in understanding and predicting ecological responses to environmental change.

A systematic survey of regional multi-taxon biodiversity: evaluating strategies and coverage

BackgroundIn light of the biodiversity crisis and our limited ability to explain variation in biodiversity, tools to quantify spatial and temporal variation in biodiversity and its underlying drivers are critically needed. Inspired by the recently published ecospace framework, we developed and tested a sampling design for environmental and biotic mapping. We selected 130 study sites (40 × 40 m) across Denmark using stratified random sampling along the major environmental gradients underlying biotic variation. Using standardized methods, we collected site species data on vascular plants, bryophytes, macrofungi, lichens, gastropods and arthropods. To evaluate sampling efficiency, we calculated regional coverage (relative to the known species number per taxonomic group), and site scale coverage (i.e., sample completeness per taxonomic group at each site). To extend taxonomic coverage to organisms that are difficult to sample by classical inventories (e.g., nematodes and non-fruiting fungi), we collected soil for metabarcoding. Finally, to assess site conditions, we mapped abiotic conditions, biotic resources and habitat continuity.ResultsDespite the 130 study sites only covering a minute fraction (0.0005%) of the total Danish terrestrial area, we found 1774 species of macrofungi (54% of the Danish fungal species pool), 663 vascular plant species (42%), 254 bryophyte species (41%) and 200 lichen species (19%). For arthropods, we observed 330 spider species (58%), 123 carabid beetle species (37%) and 99 hoverfly species (33%). Overall, sample coverage was remarkably high across taxonomic groups and sufficient to capture substantial spatial variation in biodiversity across Denmark. This inventory is nationally unprecedented in detail and resulted in the discovery of 143 species with no previous record for Denmark. Comparison between plant OTUs detected in soil DNA and observed plant species confirmed the usefulness of carefully curated environmental DNA-data. Correlations among species richness for taxonomic groups were predominantly positive, but did not correlate well among all taxa suggesting differential and complex biotic responses to environmental variation.ConclusionsWe successfully and adequately sampled a wide range of diverse taxa along key environmental gradients across Denmark using an approach that includes multi-taxon biodiversity assessment and ecospace mapping. Our approach is applicable to assessments of biodiversity in other regions and biomes where species are structured along environmental gradient.

Carabid beetle (Coleoptera: Carabidae) assemblages in the intermediate successional stage after Mt. Bandai eruption of 1888: Effects of environmental variables on carabid beetles in the Urabandai area

AbstractWe studied carabid beetle assemblage structure and species diversity in an intermediate successional stage (seral) forest established in areas affected by the 1888 eruption of Mt. Bandai and a climax forest that had not been affected by the eruption at the Urabandai area, Fukushima Prefecture, Japan. In total, 2,131 carabid beetles representing 31 species were collected using pitfall traps without bait. A comparison of carabid beetle assemblages between the two forest types revealed that the number of species observed was comparable, but their abundance was greater in the seral forest. The assemblage structure clearly differed between the two forest types. In the seral forest, forest generalists, such as Synuchus arcuaticollis and Pterostichus prolongatus, along with forest specialists including Carabus vanvolxemi and Pterostichus asymmetricus, were collected. In the climax forest, forest generalists, such as Synuchus cycloderus and Carabus albrechti tsukubanus, were more abundant than forest specialists. This suggests that the current seral forest in the Urabandai area possesses environmental variables that enable the coexistence of both forest specialist and generalist beetle species. A redundancy analysis showed that six species from the genera Synuchus and Pterostichus were associated with high canopy openness and high understory vegetation cover, whereas species recorded only in the climax forest were associated with deep litter. Therefore, it seems likely that carabid beetles in the Urabandai area were affected by these three environmental variables.

Habitat specialization, distribution range size and body size drive extinction risk in carabid beetles

The worldwide biodiversity crisis is ongoing. To slow down, or even halt future species loss it is important to identify potential drivers of extinction risk. Species traits can help to understand the underlying process of extinction risk. In a comprehensive study on 464 carabid beetle species, we used ordinal logistic regression to analyze the relationship of species traits to extinction risk in Central Europe, taking phylogenetic relatedness into account. To consider varying trait responses in different habitat types, we also tested models for species groups associated with different habitat types (forest, open, riparian and wetland). Our results identified three traits of particular importance as predictors for high extinction risk: (1) high habitat specialization, (2) small distribution range size (which is not considered in the categorization of the German Red List), and (3) large body size. Furthermore, large macropterous species showed high extinction risk. Overall, species associated with mountainous, coastal and open habitats generally revealed a high risk of extinction, while most forest species showed a low extinction risk. However, forest species with predatory feeding behavior were threatened, as were wetland species that reproduce in autumn. Phylogenetic relatedness had no influence on how species traits predict carabid beetle extinction risk. In the light of these results, management and recovery plans for species which exhibit characteristic traits strongly associated with extinction risks, as well as the conservation and restoration of mountain, coastal and open habitats, have to be prioritized.

Resolving the predator first paradox: Arthropod predator food webs in pioneer sites of glacier forelands.

Primary succession on bare ground surrounded by intact ecosystems is, during its first stages, characterized by predator‐dominated arthropod communities. However, little is known on what prey sustains these predators at the start of succession and which factors drive the structure of these food webs. As prey availability can be extremely patchy and episodic in pioneer stages, trophic networks might be highly variable. Moreover, the importance of allochthonous versus autochthonous food sources for these pioneer predators is mostly unknown. To answer these questions, the gut content of 1,832 arthropod predators, including four species of carabid beetles, two lycosid and several linyphiid spider species caught in early and late pioneer stages of three glacier forelands, was screened molecularly to track intraguild and extraguild trophic interactions among all major prey groups occurring in these systems. Two‐thirds of the 2,310 identified food detections were collembolans and intraguild prey, while one‐third were allochthonous flying insects. Predator identity and not successional stage or valley had by far the strongest impact on the trophic interaction patterns. Still, the variability of prey spectra increased significantly from early to late pioneer stage, as did the niche width of the predators. As such the structure of pioneer arthropod food webs in recently deglaciated Alpine habitats seems to be driven foremost by predator identity while site and early successional effects contribute to a lesser extent to food web variability. Our findings also suggest that in these pioneer sites, predatory arthropods depend less on allochthonous aeolian prey but are mainly sustained by prey of local production.

Reducing management intensity and isolation as promising tools to enhance ground-dwelling arthropod diversity in urban grasslands

Urbanisation is a growing global phenomenon having multiple ecological consequences. However, the effects of urbanisation on biodiversity remain ambiguous, and some evidence exists that cities provide valuable secondary habitats for many species, possibly mitigating regional biodiversity loss. Therefore, the value of urban sites for biodiversity depends on local habitat conditions and the configuration of the surrounding landscape. We aimed to disentangle the effects of local habitat parameters (management, plant diversity) and urban matrix variables (urbanisation, isolation) on carabid beetle and spider diversity and traits in informal urban green spaces in Berlin, Germany. Habitat management and isolation were the most important influences on carabid beetle and spider species and trait compositions. Spider communities of irregular managed sites contained 2.5 times more species of conservation concern than extensive (regular) managed sites. Moreover, irregular managed sites contained larger species (both for carabid beetles and spiders) and affected the hunting mode of spiders. Isolated sites tended to have lower spider species richness and number of spider species of conservation concern. Moreover, isolated sites were characterised by small, mobile and herbivorous carabid beetles. In contrast, urbanisation and local plant diversity had no effect on carabid beetles and spiders. We conclude that urban grasslands within residential areas – even if not targeted for conservation plans – can provide important habitats for conserving biodiversity, including species of conservation concern. Reducing the intensity of habitat management and increasing the connectivity of urban grassland sites can promote diverse arthropod communities and should therefore be considered in urban planning.

The consumption pattern of 28 species of carabid beetles (Carabidae) to a weed seed,Viola arvensis

Seedbank control has been the cornerstone of agricultural management practices. Regulating weeds by using their predators, as a weed control strategy, may be a prerequisite of decreasing herbicide use, and has thus attracted much research investigating the possible contribution of both vertebrates and invertebrates as weed seed predators. Carabid beetles are considered as one of the most important invertebrate seed predators in agroecosystems. We aimed at investigating carabid beetle preferences to a single prey type, seeds of Viola arvensis. We measured the consumption of seeds in 28 species of carabid beetles, under controlled experimental conditions. Two main tribes are identified in tested species, Harpalini with 12 species and Pterostichini with ten species. We found no relationships between species body mass and Viola's seed consumption, nor with the ratio between mandible length and labrum width (ML/LW). However, trends became significant with the ratio ML/LW when restricting these analyses to species that ate at least five seeds. In addition, we detected a positive and significant relationship between consumption rate and occurrence in trapping sessions over the last 3 years. These results are in favor of weed seeds control by carabids. Clear limits of this study are the use of a single seed species and under control conditions. This experimentation calls for additional studies to check for consistencies in consumption against seed species.

Rare patterns of dorsal puncture in Pterostichus oblongopunctatus (Coleoptera: Carabidae).

BackgroundThe carabid beetle species Pterostichus oblongopunctatus is common in different types of forests in Poland and Europe. With respect to this species, some unclarities exist concerning the morphological feature of punctures on the elytra. P. oblongopunctatus has dorsal pits in the third interval of the elytra, the available identification keys, however, provide inconsistent information concerning the puncture in other intervals. During long-term studies at different study sites in Poland, the first author rarely but regularly discovered individuals with unusual dorsal puncture patterns, i.e., pits in the fifth and even in the seventh interval of the elytra. Since such rare patterns might be connected with special habitat characteristics, and thus have a potential as an indicator, the aim of the study was to test if they are connected with specific subpopulations (interaction groups), if they are related to the sex or size of the beetles, and if they are related to specific habitat conditions.Material and MethodsWe counted the pits on the elytra, determined the sex, and measured the length of the right elytron of individuals of P. oblongopunctatus collected at numerous study sites located within the borders of the Regional Directory of National Forests in Piła (Western Poland) over the period 2014–2016.ResultsAltogether, 1,058 individuals of P. oblongopunctatus were subjected to statistical analysis. Almost 19% of the individuals had a dorsal puncture in the fifth interval of the elytra and about 0.7% had a dorsal puncture in the seventh interval of the elytra. In 2014 and 2015, significantly more females exhibited such unusual patterns of dorsal puncture than males. Even if not statistically significant, in 2016 also relatively more females showed such a pattern. Neither males nor females of the analysed individuals with usual puncture patterns showed a significant difference in the length of the right elytron from those with unusual puncture patterns, and neither for males nor for females a significant correlation of the percentage share of the individuals with unusual puncture patterns with the age of the study sites could be detected. However, both males and females with unusual patterns had more dorsal pits than those without. Moreover, males as well as females showed in all those years a trend that the individuals with unusual patterns have more pits in the third interval of the elytra.DiscussionThe results indicate that females are more likely to exhibit unusual patterns. Since individuals of P. oblongopunctatus with a higher number of pits on the elytra are supposed to prevail in more wet habitats, such patterns might be related to moisture conditions. The possibility of pits in the seventh interval of the elytra should be added to identification keys.

A long‐term habitat fragmentation experiment leads to morphological change in a species of carabid beetle

1. Habitat fragmentation and transformation are key drivers of species declines in landscapes. Most of the current understanding of species' responses to environmental change originates from studies of populations and communities. However, phenotypic variation offers another key aspect of species responses and could provide additional insights into the functional drivers of population change.2. The goal of this study was to address this gap by exploring the morphological changes of a species of carabid beetle (Notonomus resplendens) with a known population response to the Wog Wog Habitat Fragmentation Experiment in Australia. We measured morphological traits associated with body size, head width, and dispersal ability. We quantified patterns of morphological variation over time and between native Eucalyptus forest fragments and the surrounding pine plantation matrix and the continuous intact native Eucalyptus forest controls.3. We found sexually dimorphic morphological changes in response to the experimental treatments. Males increased in size, had larger legs and had smaller interocular widths in the matrix in both the short and long terms. Conversely, females became comparatively smaller and had increased interocular widths in the same treatments. Effects in the fragments were similar to those in the matrix, but exhibited more uncertainty.4. Our results demonstrate that species can show morphological change in response to environmental change over very short time periods. We demonstrate that using both population and morphological data allows stronger inferences about the mechanisms behind species responses to environmental change.

New species and new distributional data on Carabidae (Coleoptera) from the Socotra Archipelago

Abstract Three new species of carabid beetles of the tribe Lebiini are described: Glycia socotrana sp. nov., previously mentioned as Glycia cf. spencei (Gistel, 1838), from Socotra Island and Abd al Kuri Island; Apristus dioscoridus sp. nov. and Mesolestes niger sp. nov., both from Socotra Island. Acupalpus (Stenolophidius) posticalis (Putzeys, 1880), Harpalus (Cryptophonus) tenebrosus Dejean, 1829, and Metadromius sp. are recorded from the Socotra Archipelago for the first time. In addition, new distributional data from Socotra are given for several other carabid species.

Genomic population structure and conservation of the red listed Carabus arcensis (Coleoptera: Carabidae) in island–mainland habitats of Northern Europe

Abstract Larger carabid beetle species linked to open habitats have exhibited recent rapid decline in numbers throughout Europe. For example, Carabus arcensis is on the Danish Red List. Ability of C. arcensis to disperse across non‐habitable barriers in an island–mainland landscape has been evaluated through investigation of its population structure across Kattegat strait with special emphasis on the oceanic island Læsø. Based on admixture and statistical phylogenetic analyses of genome‐wide SNPs, data for C. arcensis comprising 3195 SNPs in 87 individuals from nine sample sites, three major lineages and six populations were found within the study area. These are the first genome‐wide SNPs data generated for carabid beetles. Contrary to predicted, water stretches did not seem to affect dispersal of C. arcensis to the island of Læsø, as isolation by distance plot showed no differences between sites connected by land and sites separated by an oceanic water gap. Unexpected high genetic diversity of the C. arcensis population on Læsø island has been observed calling for future research and explanation. High conservation priority in Denmark is suggested for smaller islands like Læsø.

Taxonomic and Compositional Differences of Ground-Dwelling Arthropods in Riparian Habitats in Glen Canyon, Arizona, USA

The disturbance history, plant species composition, productivity, and structural complexity of a site can exert bottom-up controls on arthropod diversity, abundance, and trophic structure. Regulation alters the hydrology and disturbance regimes of rivers and affects riparian habitats by changing plant quality parameters. Fifty years of regulation along the Colorado River downstream of Glen Canyon Dam has created a no-analog, postdam “lower” riparian zone close to the water's edge that includes tamarisk (Tamarix sp.), a nonnative riparian shrub. At the same time, the predam “upper” facultative riparian zone has persisted several meters above the current flood stage. In summer 2009, we used pitfall traps within these 2 riparian zones that differ in plant composition, productivity, and disturbance frequency to test for differences in arthropod community (Hymenoptera, Arachnida, and Coleoptera) structure. Arthropod community structure differed substantially between the 2 zones. Arthropod abundance and species richness was highest in the predam upper riparian zone, even though there was a greater amount of standing plant biomass in the postdam lower riparian zone. Omnivore abundance was proportionately greater in the upper riparian zone and was associated with lower estimated productivity values. Predators and detritivores were proportionately greater in the postdam lower riparian zone. In this case, river regulation may create habitats that support species of spiders and carabid beetles, but few other species that are exclusive to this zone. The combined richness found in both zones suggests a small increase in total richness and functional diversity for the Glen Canyon reach of the Colorado River.

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.

Impact of farming systems on agricultural landscapes and biodiversity: From plot to farm and landscape scales

Green-way policies in agricultural landscapes focus on ecological continuity between semi-natural elements (hedgerows, permanent grasslands, woods) and landscape heterogeneity. These policies suggest annual crops and temporary grasslands exhibit a negative or neutral impact on biodiversity. However, recent studies indicated the spatial continuities between different crops (spring vs. winter) showed positive impacts on biodiversity. These landscape patterns were directly related to farmers' decisions regarding the crops cultivated and where the crops were distributed spatially on the farm. The aim of the present study was to evaluate the impacts of different livestock farming system management types on crop patterns and associated biodiversity (carabid beetles) in agricultural landscapes. We combined empirical analyses of farmers' decision making and ecological data to develop a modeling framework simulating crop allocation and abundance of two different carabid beetle species groups (maize and woody species). Modeling included field, farm, and landscape levels. We simulated different scenarios, where two livestock farming systems, swine and dairy, were combined in different proportions (i.e. number of swine vs. dairy farms) in two agricultural landscapes with varied hedgerow densities. Simulations showed maize carabid species abundance was higher in swine production landscapes due to more frequent spatial continuities between spring and winter crops. In contrast, woody carabid species were more abundant in mixed landscapes (dairy and swine) under high crop diversity. For a given combination of livestock farming systems, simulated landscapes were highly variable in crop acreages and spatial continuities between crops. Our results emphasized the need to manage landscape at a collective level, where crop allocation decisions create more interfaces without modifying livestock farming system combinations.

Synthetic Aperture Radar (SAR) images improve habitat suitability models

Context The ability to detect ecological networks in landscapes is of utmost importance for managing biodiversity and planning corridors. Objectives The objective of this study was to evaluate the information provided by a synthetic aperture radar (SAR) image for landscape connectivity modeling compared to aerial photographs (APs). Methods We present a novel method that integrates habitat suitability derived from remote sensing imagery into a connectivity model to explain species abundance. More precisely, we compared how two resistance maps constructed using landscape and/or local metrics derived from AP or SAR imagery yield different connectivity values (based on graph theory), considering hedgerow networks and forest carabid beetle species as a model. Results We found that resistance maps using landscape and local metrics derived from SAR imagery improve landscape connectivity measures. The SAR model is the most informative, explaining 58% of the variance in forest carabid beetle abundance. This model calculates resistance values associated with homogeneous patches within hedgerows according to their suitability (canopy cover density and landscape grain) for the model species. Conclusions Our approach combines two important methods in landscape ecology: the construction of resistance maps and the use of buffers around sampling points to determine the importance of landscape factors. This study was carried out through an interdisciplinary approach involving remote sensing scientists and landscape ecologists. This study is a step forward in developing landscape metrics from satellites to monitor biodiversity.