Structure Of Carabid Assemblages Research Articles

Long-term responses of ground beetles (Coleoptera: Carabidae) to clear-cutting and wildfire in lodgepole pine stands of western Alberta, Canada

Abstract We studied responses of carabid beetles (Coleoptera: Carabidae) to clear-cutting and wildfire in lodgepole pine forests in the foothills of Alberta, Canada during 2013–2014 and compared the results with those from a similar study conducted in the same area during 1989–1990. Assemblages from stands regenerating 12–53 years after harvest gradually recovered towards their presumed preharvest condition represented by old pyrogenic stands. Assemblage structure in postharvest stands of similar age had also largely converged with that in stands that had burned in 1957 and 1997. Composition of ground vegetation, mineral soil cover, and basal area of trees and shrubs were significantly correlated with carabid assemblage structure, suggesting that plant successional gradients and patterns in carabid assemblages are driven by similar factors. We found that no carabid species was strictly associated with old pyrogenic stands, although assemblages in pyrogenic stands were distinctive. We predict that composition of carabid assemblages in harvested stands will recover and roughly match the variable structure of assemblages remaining in old, never-cut pyrogenic stands, given sufficient time (≥ 50 years). Nonetheless, the carabid fauna of the eastern slopes of Alberta’s Rocky Mountains appears to be changing in response to factors other than forestry. Warming climate is an explanation consistent with the changes observed.

Converting forests to agriculture decreases body size of Carabid assemblages in Zambia

AbstractBody size affects both intraspecific and interspecific competition. Land‐use affects such interactions within assemblages of species and should, therefore, also change the size structure of these assemblages. In particular one expects a decrease of mean body size with disturbances. We compared interspecific size structure of carabid assemblages between agricultural fields (frequent disturbances) and forests in Zambia using pitfall traps operated across 1 year. Mean body length across species co‐occurring within sites in agricultural fields was significantly smaller than in natural forests. Furthermore, in both habitats, we found evidence for ecological clustering in respect to body size, although in forests, body size differences between adjacent‐sized species tended to be overdispersed. We also found a positive relationship between log10‐transformed body length and log10‐transformed activity abundance in forests, suggesting competitive asymmetries between large and small species. Overall, these observations suggest that the size structure of carabid assemblages depends on disturbances as well as competitive interactions. Such interactions seem to be, however, of lower importance within agricultural fields.

Boreal ground-beetle (Coleoptera: Carabidae) assemblages of the mainland and islands in Lac la Ronge, Saskatchewan, Canada

AbstractWe tested the applicability of the “passive sampling” hypothesis and theory of island biogeography (TIB) for explaining the diversity of forest-dwelling carabid assemblages (Carabidae: Coleoptera) on 30 forested islands (0.2–980.7 ha) in Lac la Ronge and the adjacent mainland in Saskatchewan, Canada. Species richness per unit area increased with distance to mainland with diversity being highest on the most isolated islands. We detected neither a positive species-area relationship, nor significant differences in species richness among island size classes, or between islands and the mainland. Nonetheless, carabid assemblages distinctly differed on islands <1 ha in area and gradually approached the structure of mainland assemblages as island area increased. Small islands were characterised by abundant populations of small-bodied, winged species and few if any large-bodied, flightless species like Carabus taedatus Fabricius. Our findings suggest that neither the “passive sampling” hypothesis nor the theory of island biogeography adequately explain carabid beetle diversity patterns observed among islands in Lac la Ronge. Instead, we hypothesise that population processes such as higher extinction rates of large-bodied, flightless species and the associated release of smaller-bodied, flying species from intra-guild predation on small islands contribute to observed differences in the structure of carabid assemblages between islands.

Microhabitats and fragmentation effects on a ground beetle community (Coleoptera: Carabidae) in a mountainous beech forest landscape

The aim of this investigation was to analyze the effects of microhabitats and forest fragmentation on the composition and species abundance of a ground beetle community from three different beech forest patches on Mt. Osogovo (Macedonia), as well as to analyze the mobility (based on mark-recapture of individuals) and seasonal dynamics and sex ratio of the ground beetle community. The study site included three localities (A, B, C), one of them fragmented (A), with four microhabitats (open area, ecotone, forest stand, and forested corridor). Ground beetles were collected using pitfall traps during four sampling months (June-September 2009) that were operational for three continuous days per month. Species richness, abundance, diversity, homogeneity, and dominance were compared between the localities. Dissimilarities in carabid assemblages between localities and microhabitats were analyzed with Bray-Curtis UPGMA cluster analysis. In total 1320 carabid individuals belonging to 19 species were captured. The carabid assemblage structure of the continuous forest locality was substantially different from the other two smaller forest patches, indicating that microhabitat structure affects ground beetle communities through changes of species composition and richness.

Landscape effects of disturbance, habitat heterogeneity and spatial autocorrelation for a ground beetle (Carabidae) assemblage in mature boreal forest

Ground beetle (Carabidae) assemblages are speciose and frequently employed as indicators of ecosystem function. It is thus important to understand the factors that affect their spatial distributions so as to better interpret how ecosystem variation influences the structure of their assemblages. We evaluated how anthropogenic disturbances, habitat heterogeneity, and spatial autocorrelation (unmeasured spatially structured habitat variables and/or dispersal limitation) influence the distribution of carabids on a mature boreal forest landscape. We worked with a large sample of carabids from 194 sites from a near‐regular grid covering 70 km2. Data about forest floor cover, vegetation structure, soil drainage, and topography were associated with each site. We modelled the structure of carabid assemblages using these variables together with Moran’s eigenvector maps (MEM) as spatial constraints. Overall, our model explained about half of the variation in ground beetle assemblages. Forest floor cover, soil drainage, and vegetation structure were the principal factors useful for explaining carabid assemblages. The spatial patterns described by the MEMs for the ground beetle assemblages seem to result from spatial autocorrelation in soil drainage, floor cover, topography, and vegetation structure; however, this spatial autocorrelation independently and uniquely explained only 1.4% of the variation in assemblages. This was much less important than the explanatory power of the environmental variables considered; e.g. ground cover descriptors and vegetation structure by themselves accounted, respectively, for 12.1 and 4.5% of the variation in the carabid data. The spatial distribution of ground beetles in undisturbed forest was only mildly affected by surrounding anthropogenic disturbances, but clearly small patches were invaded by species characteristic of open habitat. We conclude that to help conserve ground beetle diversity at the landscape scale in boreal forests, mature forest patches should be large and connected to other patches and the surrounding forest.

Riparian field margins: can they enhance the functional structure of ground beetle (Coleoptera: Carabidae) assemblages in intensively managed grassland landscapes?

Summary In Europe and North America, there is growing concern that biodiversity declines associated with agricultural intensification will adversely impact the functioning and sustainability of agricultural ecosystems. Enhancing habitat heterogeneity in agricultural landscapes promotes biodiversity and, whilst erecting fences adjacent to watercourses is widely advocated as a means of mitigating diffuse pollution, associated biodiversity benefits have been largely overlooked. A range of riparian margins and their adjacent grassland fields were investigated to determine the effects of riparian management on the diversity and functional structure of carabid assemblages. Carabid assemblages of fields and open margins (i.e. unfenced watercourses) were more diverse and species rich than those of fenced margins. The functional structure of carabid assemblages in fenced margins differed from grassland fields and open margins. This disparity was greater in wide margins (i.e. fences erected over 5·4 m from watercourses) than narrow margins (i.e. fences erected within 2·6 m of watercourses). Wide margins had the highest relative proportions of carabids which had pushing body forms, were flightless, very small in size and Collembola specialists. During early summer, wide margins also had the highest proportion of carabids that overwinter as adults. The taxonomic and functional structure of carabid assemblages was more sensitive for detecting impacts of agricultural management than measurements of diversity. It is likely that this also applies to other taxa, thus emphasising the need to consider a wide range of assemblage attributes when investigating agricultural impacts on biodiversity. Synthesis and applications. Fenced riparian margins, particularly those over 5·4 m wide, harbour carabids with poor dispersal ability which are vulnerable to habitat fragmentation. While lack of management benefits sedentary species, a wider range of taxa (e.g. pollinators, foraging birds and flowering plants) are enhanced by management to obtain a more open vegetation structure (e.g. restricted grazing or mowing). It is important that management practices are implemented at a sufficiently fine spatial scale to allow recolonisation of species with restricted dispersal from adjacent undisturbed habitats. Wide riparian margins have the potential to enhance taxonomic and functional diversity at the landscape scale. Management actions must, however, be carefully balanced to ensure that they promote a wide range of taxa without unduly interfering with the margin's ability to mitigate diffuse pollution.

Effects of habitat edges and trampling on the distribution of ground beetles (Coleoptera, Carabidae) in urban forests

Urban forest patches are generally small with highly contrasting edges bordering non-forest habitat, landscape features that increase with urbanisation. These forest patches are also subject to high human foot traffic resulting in trampling and other user disturbances that affect their quality as habitat for invertebrates. We studied the effects of these factors on carabid beetles in urban forests in the cities of Helsinki (Finland) and Edmonton (Canada). In both cities, the structure of carabid assemblages was affected by trampling intensity and distance to the forest edge. Moderate intensity of trail use was associated with increased beetle captures, especially in Edmonton. The effects on individual species were apparent in Edmonton but harder to demonstrate in Helsinki where forest specialist species may have been largely extirpated already. We suggest that these differences result because there has been a long history of fragmentation of urban forest patches in Helsinki, species loss from such patches is gradual, and understorey vegetation structure constrains human foot traffic in forest patches more in Edmonton than it does in Helsinki.

Effects of crop rotation and genetically modified herbicide-tolerant corn on ground beetle diversity, community structure, and activity density

AbstractGround beetles (Coleoptera: Carabidae) were sampled in conventional and genetically modified herbicide-tolerant (GMHT) corn, Zea mays L. (Poaceae), planted under rotation with canola, Brassica L. (Brassicaceae), or continuously cropped corn to investigate the influence of corn variety and rotation on the structure of carabid assemblages. Corn variety, cultivation regime, and their interaction all influenced overall carabid activity density. Weed management associated with corn variety influenced the activity density of a few carabid species and this was attributed to changes in vegetation. Some smaller bodied carabids such as Bembidion quadrimaculatum L. were less abundant in GMHT plots, probably because weed density was higher in midseason, but the opposite was observed for larger bodied carabids such as Pterostichus melanarius (Illiger). Overall, rotating corn with canola had a stronger effect on carabid community structure than did corn variety. We suggest that GMHT corn has little impact on the overall carabid fauna but may influence the activity of certain species through effects on the weed community.

The influence of riparian buffer strips on carabid beetle (Coleoptera, Carabidae) assemblage structure and diversity in intensively managed grassland fields

The use of riparian buffer strips as a means of reducing diffuse pollution in European grassland systems is becoming more common and consequently there is a need for comprehensive research on the influence of buffer strip management, placement and structure on biodiversity. Carabid assemblages were examined in a range of riparian zones in intensively managed grassland in Scotland. Carabids were monitored by pitfall trapping in riparian zones open to grazing, wide riparian buffer strips (>5 m wide), narrow boundary strips (<2 m wide) and adjacent fields in order to determine factors influencing carabid diversity and assemblage structure. While carabid diversity was greater in open riparian zones and narrow boundary strips when compared to the adjacent fields, it was actually poorer in wide riparian buffers when compared to open zones thus indicating wide buffers may actually be detrimental to carabid diversity. Carabid assemblages in wide riparian buffers were, however, more distinct from the adjacent field than narrow boundary strips or riparian zones open to grazing. Consequently, while the presence of wide riparian buffers may not promote carabid diversity within the actual buffer strips, by adding an additional habitat that supports a distinct carabid assemblage, riparian buffer strips may promote diversity at the landscape level. Carabid assemblage structure was driven by a combination of soil and vegetation characteristics in addition to physical attributes including distance from the watercourse and width of the strip. Only when we have a better understanding of the factors influencing biodiversity within riparian buffer strips can we start to formulate effective management prescriptions that fuse their dual function of pollution mitigation and biodiversity promotion.

Traditional forest management: Do carabid beetles respond to human-created vegetation structures in an oak mosaic landscape?

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 11 370 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.

Distribution of carabid beetles among regenerating and natural forest types in Southwestern China

Heterogeneity in species assemblages of carabid beetles was studied between regenerating larch plantations of different forest ages and natural deciduous broad-leaved forests in Southwestern China. Larch plantations that were dominated by the non-native tree species ( Larix kaempferi) interspersed with a small proportion of native tree species ( L. mastersian) were established after the clear-cutting of the natural deciduous broad-leaved forests. Using pitfall traps, we compared the distribution of carabid beetles in recently planted (5 years old), young (15 years old), mature plantation (45 years old) and adjacent natural deciduous broad-leaved forests (ca. 100 years old). Four replicated plots for each plantation and five replicated transects in natural broad-leaved forest were chosen, and each plot or transect was investigated with four trap locations twice each month during the growing season (May–October) in 2004. Our results showed that species richness, abundance and Shannon diversity were significantly higher in the natural forest than in the regenerating plantations. In addition, these indices were not significantly different in 15- and 45-year-old plantations but were higher than those in 5-year-old plantation. Principal coordinate analysis (PCoA) ordination grouped the carabid assemblages according to forest type and forest age, suggesting that there is a general pattern of recovery after logging. Moreover, indicator species analysis detected significant species associated with forest types and ages. Based on the specificity and fidelity, carabids can be distinguished into six species groups: habitat generalists, generalists in forests with closed canopy, specialists in natural broad-leaved forest, generalists in plantations with closed canopy, young closed canopy larch plantation-associated species and open canopy larch plantation-associated species. Multiple linear regression showed that the depth of leaf litter, the cover of canopy and shrub layer had significant effects in determining richness, abundance and diversity of carabid beetles. Therefore, the regenerating larch plantations, even mature plantations, could not replace the role of the natural deciduous broad-leaved forests in sustaining the diversity of carabid assemblages. Furthermore, establishments of large areas of relatively homogeneous larch plantations may have detrimental long-term effects on the composition and structure of carabid assemblages. Thus, it is important for us to understand the subtle variations in habitat and take appropriate actions for maintaining the invertebrate diversity before the logging of natural forests and establishments of plantations.

Responses of boreal carabid beetle assemblages (Coleoptera, Carabidae) to clear-cutting and top-soil preparation

Today, forestry is the most important disturbance force in Fennoscandian boreal forests, having remarkably altered fauna and flora in this biome. However, since the late 1900s, forest-management practices have been modified to better consider biodiversity while harvesting timber. For example, green-tree retention, gap felling, and lighter top-soil preparation methods (harrowing) have been introduced, but little is known about the ecological effects of these changes. We sampled carabid beetles in seven clear-cut stands that were subsequently harrowed. We studied the effects of (1) clear-cut size by comparing carabid catches of small gaps (ca. 0.16 ha) with those of larger clear-cuts (ca. 2 ha), and (2) micro-site type within stands by comparing carabid catches of strips of bare soil to those of drifted humus (adjacent to bare-soil strips) and undisturbed (not scarified) forest floor. We detected only slight effects of clear-cut size on the assemblage structure, but clearer differences at species and ecological-group levels among the three compared micro-site types. The catches of forest carabids, and flightless carabids, were higher in the undisturbed micro-sites as compared to bare-soil ones, whereas open-habitat carabids showed the opposite abundance pattern. The variation among study blocks, and logging per se (compared to un-logged mature stands), had more pronounced effects on carabid assemblage structure than either clear-cut size or micro-site.

Year‐to‐year variation in carabid beetle (Coleoptera, Carabidae) assemblages on the Åland Islands, south‐west Finland

Aims(1) To investigate changes in structure of carabid assemblages between sites on the main island of Åland and five small nearby islands between 1982 and 1999. (2) To determine whether island differences observed in one year is mirrored in another one. (3) To examine changes in abundance levels of individual carabid species on these islands since 1982. (4) To compare the proportion of flightless species on the main island of Åland with those on the small islands.LocationIslands in the Baltic Sea, Finland; the main island of Åland (90,000 ha) and five small, nearby islands (8–29 ha).MethodsCarabid beetles were collected, using pitfall traps, during 4 years (1982, 1987, 1988 and 1999). Sampling took place in moist, spruce‐dominated, lush forest patches.ResultsOverall, 12,127 individuals representing forty‐six carabid species were collected; forty‐one species (8580 individuals) on the main island of Åland, and thirty‐one species (3547 individuals) on the small islands. Carabid assemblage structure, measured using ordination techniques, was consistently and significantly different between the main island and the small island sites. Carabid assemblage structure and abundances of individual species did change significantly between years, possibly because of a combination of climatological and habitat changes in the Åland archipelago. The six most abundant species collected on the small islands, and the three most abundant species overall, were all short‐winged. Furthermore, the small islands had a higher proportion and number of short‐winged species compared with the main island of Åland.Main conclusionsCarabid assemblage structure was significantly different between the main island and the small islands in all years sampled, indicating that single‐year studies are sufficient to demonstrate differences in carabid assemblages on Baltic islands. Small islands host a non‐random proportion of species pools available on the main island of Åland and mainland Finland. It appears that dispersal to islands in the Baltic Sea is easy for carabid beetles of all wing forms, but that short‐winged species are more successful colonizers.

Invertebrate conservation at the interface between the grassland matrix and natural Afromontane forest fragments

Diversity patterns of amphipods, carabid beetles and ants were investigated in five naturally-fragmented Afromontane forest remnants, and in the surrounding grassland matrix. Forests were architecturally similar. In contrast, grasslands surrounding these forests are subject to great differences in anthropogenic impacts. Consequently, transition from forest to grassland ranged from being abrupt (heavy disturbance) to gradual (little disturbance). Significantly different mean numbers of carabid individuals and species were captured between sites and multivariate analyses showed clear separation in carabid assemblage-structure with level of disturbance. Carabids were, furthermore, significantly more diverse in forests, compared to grasslands. Ants, however, were equally species rich between sites but were significantly more abundant and species rich in grasslands than forests. Amphipods, represented here by a single species, Talistroides africana, was significantly less abundant at highly disturbed sites and significantly more abundant in forests than grasslands. Results support the hypothesis that the dynamics of remnants are influenced by their surrounding landscape. Here, the dynamics of amphipods and carabids (predominantly forest taxa) were influenced by different disturbance regimes in grasslands surrounding these forests. Epigaeic ants, a predominantly grassland taxon here, also showed significant differences in assemblage-composition between sites with varying disturbance. Conserving Afromontane grasslands should be of prime concern because this will include the protection of forest/grassland ecotones and forest remnants.