Search

Little is known about the successional dynamics of insects in the highly threatened tropical dry forest (TDF) ecosystem. For the first time, we studied the response of carabid beetles to vegetal succession and seasonality in this ecosystem in Colombia. Carabid beetles were collected from three TDF habitat types in two regions in Colombia: initial successional state (pasture), early succession, and intermediate succession (forest). The surveys were performed monthly for 13 months in one of the regions (Armero) and during two months, one in the dry and one in the wet season, in the other region (Cambao). A set of environmental variables were recorded per month at each site. Twenty-four carabid beetle species were collected during the study. Calosoma alternans and Megacephala affinis were the most abundant species, while most species were of low abundance. Forest and pasture beetle assemblages were distinct, while the early succession assemblage overlapped with these assemblages. Canopy cover, litter depth, and soil and air temperatures were important in structuring the assemblages. Even though seasonality did not affect the carabid beetle assemblage, individual species responded positively to the wet season. It is shown that early successional areas in TDF could potentially act as habitat corridors for species to recolonize forest areas, since these successional areas host a number of species that inhabit forests and pastures. Climatic variation, like the El Niño episode during this study, appears to affect the carabid beetle assemblage negatively, exasperating concerns of this already threatened tropical ecosystem. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Matrix contrasts affect communities in patchy landscapes by influencing resources, abiotic conditions and spill-over effects. However, current knowledge is significantly biased towards forest and rural communities. We examined the effects of three different matrix types, i.e., low, intermediate and high contrasts, on carabid beetle assemblages at urban railway verges in two climatic regions. Study sites were located in Finland and in Slovenia. Using pitfall trapping, non-metric multidimensional scaling and generalised linear mixed models, we investigated carabid assemblages at railway verges and in differently contrasting adjacent matrices, i.e. built-up, grassland and forest. The matrix influenced carabid assemblages at railway verges. Assemblages grouped with adjacent matrix types, although some Finnish railway assemblages included a characteristic set of open dry habitat species. Abundances of generalist species at railway verges were higher when next to grassland or forest than urban matrices. Habitat specialists responded negatively to high contrast matrices, resulting in lower abundances of open habitat specialists in railway verges when next to forests and nearly no spill-over of forest specialists into railway verges. These patterns were consistent in both countries, i.e. irrespective of climatic region. Our study emphasises effects of the adjacent matrix and matrix contrasts on communities in linear open habitat patches in cities. Knowledge on matrix effects in patchy landscapes, such as urban environments, is essential in understanding the distribution and composition of communities in discrete patches. This knowledge can be used in conservation planning. If habitat specialists are negatively affected by high matrix contrasts, high contrasts should be avoided. [ABSTRACT FROM AUTHOR]

Some golf courses start off as half-size, 9-hole courses and, if successful, expand in area to full-size courses, thus converting more land to highly managed greenspace. We investigated carabid beetle assemblages in three established and newly created suburban golf courses in Helsinki, southern Finland., Beetles were collected from similar habitat types on established courses, newly created courses and nearby reference areas., Seventy-one carabid beetle species were collected and the beetle assemblages were dominated by open habitat and generalist species., Assemblages differed considerably between the three golf courses studied and between the habitat types sampled, but not between course development stages (established vs. newly created) or reference areas., We argue that some carabid beetle species in the urban landscape in Helsinki are resilient and capable of rapidly colonising these modified environments., Under current management regimes, these golf courses in Helsinki, Finland, do not host carabid beetles of conservation concern, yet are rich in generalist and open habitat species. [ABSTRACT FROM AUTHOR]

Temporal variation in the detectability of a species can bias estimates of relative abundance if not handled correctly. For example, when effort varies in space and/or time it becomes necessary to take variation in detectability into account when data are analyzed. We demonstrate the importance of incorporating seasonality into the analysis of data with unequal sample sizes due to lost traps at a particular density of a species. A case study of count data was simulated using a springactive carabid beetle. Traps were 'lost' randomly during high beetle activity in high abundance sites and during low beetle activity in low abundance sites. Five different models were fitted to datasets with different levels of loss. If sample sizes were unequal and a seasonality variable was not included in models that assumed the number of individuals was log-normally distributed, the models severely under- or overestimated the true effect size. Results did not improve when seasonality and number of trapping days were included in these models as offset terms, but only performed well when the response variable was specified as following a negative binomial distribution. Finally, if seasonal variation of a species is unknown, which is often the case, seasonality can be added as a free factor, resulting in well-performing negative binomial models. Based on these results we recommend (a) add sampling effort (number of trapping days in our example) to the models as an offset term, (b) if precise information is available on seasonal variation in detectability of a study object, add seasonality to the models as an offset term; (c) if information on seasonal variation in detectability is inadequate, add seasonality as a free factor; and (d) specify the response variable of count data as following a negative binomial or over-dispersed Poisson distribution. [ABSTRACT FROM AUTHOR]

Species rich semi-natural grasslands are disappearing across Europe, affecting invertebrate diversity negatively. In NW Spain, the recent abandonment of traditional farming practices and the gradual decrease in grazing pressures are reducing the number and extent of montane grasslands. In this context, we investigated the composition of carabid beetle (Coleoptera, Carabidae) assemblages that inhabit semi-natural grasslands situated in long-term managed oak and beech forested landscapes. According to their spatial arrangement, the studied grasslands were classified into: (1) interior or gap grasslands (small and completely surrounded by continuous forest) and (2) exterior grasslands (large and connected to a variety of habitat types). Our results indicate that, within each forested landscape, the gap and exterior grasslands harboured particular carabid assemblages (i.e. exclusive or abundantly collected species), which were also distinct from the surrounding forest carabid fauna. Dissimilarities between gap and exterior grasslands in each landscape suggest great carabid diversity at the regional scale. We also detected species-specific responses as several carabids were mainly associated with gap or exterior grasslands. Consequently, in highly modified forested landscapes, semi-natural grassland remnants may constitute great value for the protection of the carabid fauna. Specifically, we recommend conservation strategies that preserve variety in grassland features and maintain proper management activities to prevent the loss of specialised species and a decrease in regional carabid diversity. [ABSTRACT FROM AUTHOR]

1. Anthropogenic pressures have produced heterogeneous landscapes expected to influence diversity differently across trophic levels and spatial scales. 2. We tested how activity density and species richness of carabid trophic groups responded to local habitat and landscape structure (forest percentage cover and habitat richness) in 48 landscape parcels (1 km2) across eight European countries. 3. Local habitat affected activity density, but not species richness, of both trophic groups. Activity densities were greater in rotational cropping compared with other habitats; phytophage densities were also greater in grassland than forest habitats. 4. Controlling for country and habitat effects, we found general trophic group responses to landscape structure. Activity densities of phytophages were positively correlated, and zoophages uncorrelated, with increasing habitat richness. This differential functional group response to landscape structure was consistent across Europe, indicated by a lack of a country × habitat richness interaction. Species richness was unaffected by landscape structure. 5. Phytophage sensitivity to landscape structure may arise from relative dependency on seed from ruderal plants. This trophic adaptation, rare in Carabidae, leads to lower phytophage numbers, increasing vulnerability to demographic and stochastic processes that the greater abundance, species richness, and broader diet of the zoophage group may insure against. [ABSTRACT FROM AUTHOR]

Abstract: Urbanisation causes similar landscape patterns across the world; cities are characterised by a densely populated and highly disturbed urban core, a less disturbed suburban zone and a least disturbed rural surroundings. In 1998, we set up a project to investigate the effects of this urbanisation gradient on the responses of carabid beetles (Carabidae, Coleoptera) in different cities across the globe. To date, eight cities have participated in this project and the findings can be summarised as follows. In general, carabid abundance and species richness increased from the city centres to the rural surroundings. Forest specialist species tended to be more common in suburban and rural zones, while open-habitat species predominate in the urban core. The highly disturbed urban environments were also generally characterised by a few dominant species and species capable of flight, while suburban and rural areas were characterised by larger-sized species and species incapable of flight. Deviations from these general patters do occur, notably the occurrence and high abundance of introduced carabid species in urban Edmonton, Canada. The challenge now is to infer process from these patterns. In particular, community and species specific responses need to be related to characteristics of the urbanised landscape, i.e. the urban–rural gradient needs to be operationalised in terms of specific disturbance features. Furthermore, the results should now be communicated to decision-makers so that they can be considered in planning. [Copyright &y& Elsevier]

Copyright of Basic & Applied Ecology is the property of Urban & Fischer Verlag and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

As compared to natural forests, managed boreal forests are younger, more homogeneous in terms of tree age and species composition, and consist of smaller fragments. Here we examine the effects of such characteristics caused by forestry on carabid beetles (Coleoptera, Carabidae) in the boreal region. The main results are the following. (1) Fragmentation of forests and the size of a fragment appear not to be crucial for the survival of the majority of forest carabids, as they tend to be distributed over various successional stages, but species requiring old-growth habitats suffer. (2) For carabids there appear to be no or very few edge specialist species, and forest-open land edges appear to be effective barriers for species associated with forest or open habitat. However, generalist species easily cross the edge, and edges of forest fragments may be invaded by species from the surrounding open habitat. (3) Habitat change following clear-cutting dramatically changes the composition of carabid assemblages: species restricted to mature forests disappear and open-habitat species invade, while habitat generalists survive at least in the short term. Carabid diversity can probably best be maintained if forest management mimics natural processes, maintains natural structures and includes the natural composition of vegetation and other structural elements (such as dead wood) within the stands, provided that these forest features can be maintained and recreated through forest management practices. At a larger scale, the whole spectrum of forest types and ages (especially old-growth forests), and different successional processes (especially fire) should be maintained. These require the development and use of innovative logging methods, and the planning, implementation, and assessment of landscape-scale ecological management strategies. [ABSTRACT FROM AUTHOR]

Abstract: We studied the effects of traditional forest management practices (i.e. forest exploitation activities such as burning, cutting and livestock grazing) on carabid beetle (Coleoptera, Carabidae) assemblages in Pyrenean oak forests of NW Spain. A total of 11370 carabid individuals representing 61 species were collected by pitfall trapping from May to October 2004 in four types of traditionally managed oak ecosystems: “dehesa”, “mature open”, “mature closed” and “young”. These four management types experienced a variety of anthropogenic activities, resulting in differences in the structure and composition of the tree and understorey vegetation layers. We showed that the four management types were quite similar at the carabid assemblage level, mainly supporting open habitat and generalist species. The “dehesa” system was most distinct with a higher species richness (not significantly) and with several unique species, probably travelling from the adjacent grassland. However, many species responded significantly to the type of management, depending on the habitat associations of the species. We also found strong responses of some of the species to one type of management, either positive (exclusively collected from one management type) or negatively (completely absent). Shrub cover and soil organic matter content were the main environmental variables determining the carabid assemblage structure. At the regional scale, the four management types accounted for a high carabid beetle diversity. This diversity appears to be threatened by landscape homogenization, since traditional management practices are disappearing due to recent land-use changes in the area. [Copyright &y& Elsevier]

We investigated some of the causes of ground beetle decline using atlas data from Belgium, Denmark and the Netherlands, countries in which natural environments have all but disappeared. We used ordinal regression to identify characteristics that are significantly correlated with the decline of carabid beetle species over the last 50–100 years, using a stepwise selection procedure to select the optimal model according to the Akaike Information Criterion. The results showed that large-bodied carabid populations have declined more than smaller ones, possibly because of their lower reproductive output and lower powers of dispersal. Habitat specialist populations (i.e. species with small niche breadths) have also decreased more than habitat generalist populations. Species with both long- and short-winged individuals have been less prone to decline than those that are exclusively either short-winged or long-winged. Dimorphic species may survive better in highly altered environments because long-winged individuals are good at dispersing between suitable habitats and short-winged individuals are good at surviving and reproducing in these newly colonised habitats. Finally, populations of large carabids associated with coastal, woodland or riparian habitat types were less prone to decline than populations of large carabids associated with various, open or grassland habitat types. The pattern is reversed for carabid species smaller than 8 mm in size. These results are explained in the context of habitat restoration and destruction in these highly modified western European countries. [ABSTRACT FROM AUTHOR]

To investigate the effects of urbanization on carabid beetles (Carabidae) and ground dwelling spiders (Araneae) a study was completed along a 20 km urban–rural forest gradient in the Helsinki–Espoo area of southern Finland. To study changes in assemblage structure, abundance and species richness, these taxa were collected in the year 2000 using pitfall traps, which had been placed in four forest sites within each of the urban, suburban and rural zones. We expected to find changes in the abundances and species richnesses in the two taxa across the urban–rural gradient, but did not find any. Our second and third hypotheses, stating that generalist species and small-bodied species should gain dominance along the gradient from rural to urban sites, were partly supported as carabid specialists were more characteristic of suburban and rural environments whereas generalists were more likely to be collected from rural areas compared to suburban or urban sites. Furthermore, medium to large-sized carabid individuals were more likely to be collected in the rural sites compared to urban forests. We found no evidence for significant changes in spider abundance or species richness across the urban–rural gradient in relation to body size or habitat specialization. We suggest that urbanization does not have significant effects on the total abundances and species richnesses in these two taxa. However, individual species responded differently to urbanization, and there were significant differences in the specialization and body sizes of carabids across the gradient. [ABSTRACT FROM AUTHOR]

Abstract Aims (1) To test whether there is a significant increase in carabid species richness with an increase in island size and, if so, if it is due to island area per se or habitat diversity. (2) To investigate whether scattered islands accumulate species quicker than islands close to each other, per island size. (3) To investigate changes in the proportions of carabid wing morphs between the Finnish mainland and islands in the Baltic Sea. Location Islands in the south-western archipelago of Finland, in the Baltic Sea. Methods Carabid beetles were collected using pitfall traps (diameter, 65 mm; volume, 170 mL), half-filled with an ethylene-glycol–water mixture, from 22 May to 20 September 1993 on 24 islands. Island size varied between 0.5 and c. 7000 ha, and each island had between one and four habitat types sampled. Results A total of 61 carabid species were captured on these islands. Pterostichus niger was numerically dominant on 15 of the 24 islands and made up 34.5% of the total catch. The islands had a significantly higher proportion of brachypterous species compared to the Finnish mainland. The islands also accumulated species at a much slower rate (z = 0.06) than that generally observed in the literature, and, for carabids, a mainly predacious group, habitat diversity had little predictive power in explaining species richness. Islands close to each other (a few hundred metres apart) accumulated species at a slower rate than did scattered islands, as island size increased. Main conclusions Although carabids disperse relatively easily to remote islands (perhaps a result of low Baltic Sea salinity and short interisland distances), colonization success appears to depend on a multitude of factors, including availability of suitable habitat on these islands, competitive superiority, survival ability during dispersal and island arrival sequence. [ABSTRACT FROM AUTHOR]