Boreal carabid-beetle (Coleoptera, Carabidae) assemblages along the clear-cut originated succession gradient

We examined the occurrence of carabid beetles along a forest successiongradient in central Finland (forest age classes: 5, 10, 20, 30 and 60years since clear-cutting). Species richness of carabids was higherin the two youngest age classes, while no clear differences were detected incarabid abundance. The high species richness in the young, open sites was due toinvasion of open-habitat species. Many forest species were absent from or scarcein the young sites and became gradually more abundant towards the older forestage classes. The catches indicated a drastic decrease and assemblage-levelchange in concert with canopy closure, i.e. 20–30 years afterclear-cutting. Some forest specialists with poor dispersal ability may facelocal extinction, if the proportion of mature forest decreases further and theremaining mature stands become more isolated. We recommend that, whileharvesting timber, connectivity between mature stands is ensured, mature standsare maintained close (a few tens of metres) to each other and the matrix qualityis improved for forest species by green tree retention.     

Assemblages of carabid beetles (Coleoptera, Carabidae) in humid forest habitats of different stages of succession in the Puszcza Knyszyńska Forest (northeastern Poland)

During a period of three years (2006-2008) the carabid fauna in wet and humid forest habitats of different stages of succession was studied at the Puszcza Knyszynska (north-east part of Poland). The aim of this study was to determine how the assemblages of the carabid fauna change in relation to the ongoing process of succession. Using pitfall traps, 24 plots were sampled. The plots were located in stands of different age, from two year old plantations to more than 100 year old forests. Additionally, the stands were ordered in three moisture classes (wet, humid and very humid) and two classes of soil richness. As indicators for change in the carabid fauna in relation to age of the stands Mean Individual Biomass (MIB), species diversity and share of forest species were used. By applying multivariate statistics the relation of the different habitat characteristics to changes in the carabid fauna was examined. During the study 8903 individuals belonging to 57 species were collected. Pterostichus niger represented 28% of the total catches and therefore the most common species. Another common species, Pterostichus melanarius, contributed to 13% of the total catch. This species was caught at every plot, even in the old forests. In contrast to the results obtained by Szyszko (1990) for fresh and dry pine stands, in this study the relation of MIB with the age of forest was not significant. Although the number of species was rather constant, the number of individuals belonging to the group of forest species significantly increased with the ageing of the forest. The multivariate analysis showed a relationship with ageing of the stands and soil richness rather than with moisture and size of the forest. According to the present paper, clear cuttings in wet and humid habitats do not cause a strong degradation of the carabid fauna.     

Changes in ground beetle diversity and community composition in age structured forests (Coleoptera, Carabidae)

We examined diversity, community composition, and wing-state of Carabidae as a function of forest age in Piedmont North Carolina. Carabidae were collected monthly from 396 pitfall traps (12×33 sites) from March 2009 through February 2010, representing 5 forest age classes approximately 0, 10, 50, 85, and 150 years old. A total of 2,568 individuals, representing 30 genera and 63 species, were collected. Carabid species diversity, as estimated by six diversity indices, was significantly different between the oldest and youngest forest age classes for four of the six indices. Most carabid species were habitat generalists, occurring in all or most of the forest age classes. Carabid species composition varied across forest age classes. Seventeen carabid species were identified as potential candidates for ecological indicators of forest age. Non-metric multidimensional scaling (NMDS) showed separation among forest age classes in terms of carabid beetle community composition. The proportion of individuals capable of flight decreased significantly with forest age.     

Relevance of exotic pine plantations as a surrogate habitat for ground beetles (Carabidae) where native forest is rare

Plantation forests are of increasing importance worldwide for wood and fibre production, and in some areas they are the only forest cover. Here we investigate the potential role of exotic plantations in supporting native forest-dwelling carabid beetles in regions that have experienced extensive deforestation. On the Canterbury Plains of New Zealand, more than 99% of the previous native forest cover has been lost, and today exotic pine (Pinus radiata) plantations are the only forest habitat of substantial area. Carabids were caught with pitfall traps in native kanuka (Kunzea ericoides) forest remnants and in a neighbouring pine plantation, grassland and gorse (Ulex europaeus) shrubland. A total of 2,700 individuals were caught, with significantly greater abundance in traps in young pine, grassland and gorse habitats than in kanuka and older pine. Rarefied species richness was greatest in kanuka, a habitat that supported two forest specialist species not present in other habitat types. A critically endangered species was found only in the exotic plantation forest, which also acts as a surrogate habitat for most carabids associated with kanuka forest. The few remaining native forest patches are of critical importance to conservation on the Canterbury Plains, but in the absence of larger native forest areas plantation forests are more valuable for carabid conservation than the exotic grassland that dominates the region.     

Estimated density of four carabid beetle species in Mongolian oak and Korean red pine forest ecosystems on Baekdudaegan mountain range (Mt. Oade and Mt. Guryong) of South Korea

The estimation of animal population size is a primary field of interest for wildlife biologists, and such numerical estimation of wild animals is a very important factor in establishing national policy towards nature. Therefore, we performed this study to estimate the population density of carabid beetles preying on soil biota at the Mongolian oak (Quercus mongolica) forests and Korean red pine (Pinus densiflora) forests of two mountains, Mt. Odae and Mt. Guryong. We used the trapping web method with pitfall traps to collect the beetles. We calculated the estimated density of a total of four carabid beetle species in two specific regions and converted them to an estimated beetle population size within a certain area by using the study area. From our estimates, one beetle species, Leptocarabus seishinensis seishinensis L., displayed statistically significant results. Although there was no appreciable difference in the makeup of different carabid beetle species between the two forest communities, the population size of the beetle species was larger in Mongolian oak forests than in Korean red pine forests. The spatial distribution of carabid beetles by forest type did not show any preference for particular spots. Our results showed that carabid beetles did not have specific home ranges and that they were not density dependent. We expect to use the raw data to recognize the response of soil organisms to changes in the habitat environment and to track the patterns of change more accurately over long passages of time.     

Ecological Succession of a Relict Central European Peat Bog and Variability of Its Insect Biodiversity

The isolated habitat of the ervené Blato bog (South Bohemia, Czech Republic) and its relict insect fauna have been the subject of long-term monitoring. The species composition and abundance of Lepidoptera (light traps) and Coleoptera (pitfall traps) were monitored for 4 years (1994–1997) simultaneously on two sites – in the edaphic climax pine forest and in wetland successional habitats. The method of statistical evaluation by RDA and CCA ordination, representing the habitat preference of species of Coleoptera (Carabidae only) and Lepidoptera (all nocturnal phototactic taxa) between the edaphic climax forest and succession stages, was used. All categories of the peatland taxa (tyrphobiontic, tyrphophilous and tyrphoneutral species) were analysed. Ten highly stenotopic tyrphobiontic species and 23 tyrphophilous species of Lepidoptera (out of 487) were most characteristic of the bog habitat. Only two tyrphophilous carabid species (out of 20) were characteristic of the bog. The most important relict species (tyrphobionts) of Lepidoptera are most diverse and abundant within the successional habitats and in the open wet forest. The relict fauna of the closed climax pine forest is much less diverse and composed mostly of abundant tyrphophilous and tyrphoneutral forest species. Preservation or restoration of sufficiently constant hydrological conditions, which prevents formation of the closed forest, is the basic management for habitat conservation of all relict tyrphobiontic species of the ervené Blato bog and similar peat land habitat islands. The peat bog is a unified complex system of specific diverse and relict taxa. The most specific taxa are tyrphobiontic Lepidoptera, but a number of other vulnerable tyrphophilous and tyrphoneutral insects are associated with the peat bog as well.     

Response of carabid beetles (Coleoptera: Carabidae) and spiders (Araneae) to coastal heathland succession

We analyzed the impacts of succession and grass encroachment on carabid beetle and spider assemblages in a coastal heathland. Further, indicator species for different successional stages (grey dunes, dwarf-shrub heath, grassy heath, heath with shrubs, birch forest) were identified, and their relations to habitat parameters were analyzed. The study was conducted on the Baltic island of Hiddensee, Germany. Ground-dwelling arthropods were sampled using pitfall traps along a successional gradient containing five stages. Ordination by nonmetric multidimensional scaling (NMDS) and analysis of similarities (ANOSIM) revealed a clear separation of species composition among the successional stages. Both in carabid beetles and spiders, most indicator species were obtained in the youngest stage (grey dunes) and fewest in the intermediate stages (grassy heath, heath with shrubs). Also the proportion of endangered species was highest in grey dunes. Based on our results, conservation management of coastal heathlands should preserve a mosaic of different successional stages with a clear preference on younger stages (grey dunes and dwarf-shrub heath).     

Life-history trait and functional diversity patterns of ground beetles and spiders along a coastal heathland successional gradient

We investigated patterns in species richness and diversity, life-history traits and functional diversity of carabid beetles and spiders along a coastal heathland successional gradient. We sampled in five successional stages on the island of Hiddensee, Germany. Species richness of carabids and spiders and Simpson diversity for spiders did not differ among stages. Functional dispersion (FDis), a measure of functional richness, was lowest in the youngest stage for both carabids and spiders. Older successional stages represent more heterogeneous habitats and offer a broader range of niches, which might enhance functional dispersion. Functional evenness (FEve) differed among successional stages for spiders, indicating an uneven distribution of species abundances in the functional trait space. Functional divergence (FDiv) did not differ among stages for either taxon. Shifts in life-history traits were noted in both arthropod groups, but not always in the same direction: Body size of carabid beetles increased towards older successional stages, but decreased for spiders. The number of flightless carabid species increased towards older habitats. Each successional stage seemingly favors species with distinct life-history traits (species sorting). We conclude that a trait-based approach including the use of functional diversity measurements (FDis) could contribute valuable information for biodiversity conservation.     

Comparison between the soil seed banks of a burnt and an unburnt Quercus pyrenaica Willd. forest

Soil samples from burnt and unburnt sites dominated by Quercus pyrenaica Willd. forest in León province (NW Spain) were collected, separated into an upper layer (0–2 cm depth) from a lower layer (2–5 cm), put in a greenhouse, and seeds allowed to germinate.A total of 670 identified seedlings comprising 56 species and belonging to 24 families were recorded. Most seedling were herbaceous perennials (hemicryptophytes: 59%), followed by annuals (therophytes: 23%). Many species that germinated from buried seeds were not observed as plants at any site, and came from exogenous communities. The principal means of seed dissemination were anemochory (45%) and autochory (23%).The number of species as well as seedlings was not significantly different between soils from the burnt and unburnt sites, but seedlings were more numerous in samples from the unburnt sites, as the number of seedlings was always highest in the upper soil layer. Germination behaviour of four particular species was characterized.Seedlings from the seed bank temporarily were found in the early stages of recovery of the burnt Quercus pyrenaica forests.     

Effects of Clearfell Harvesting on Lucanid Beetles (Coleoptera: Lucanidae) in Wet and Dry Sclerophyll Forests in Tasmania

The effects of commercial forestry harvest and regeneration practices (clearfelling and slash-burning) on the lucanid fauna of the wet sclerophyll forests of southern Tasmania and the dry sclerophyll forests of eastern Tasmania were examined using pitfall catches. Lucanids are saproxylic beetles, dependent on dead, moribund and decaying wood. Samples taken from old-growth forest and from a chronosequence of sites regenerating after logging, in each forest type, were used to compare the species richness and abundance of the lucanid assemblages. In both forest types, species richness and abundance was highest in the youngest regeneration sites (1–3 year), reflecting the species richness of the original and adjacent unlogged forest, lowest in the older (20–25 year) sites, and variable in the old-growth sites. TWINSPAN cluster analysis showed no clear distinction between regeneration and old-growth forest. The post-harvest slash and stump residue provided an important refugium and initial habitat, but our research indicates that some species may not maintain populations in the long term. Our results suggest that most species of lucanids will find a continuous supply of suitable habitat only in old-growth forests; and such species may become less common as clearfell harvesting leads to a replacement of heterogeneous old-growth forest with single-aged monospecific stands. Continuity of supply of wood in all decay stages, the maintenance of sufficient source areas, and biological connectivity between old-growth stands to enable dispersal, are all likely to be essential to maintain lucanid beetle community integrity. If similar principles apply to other saproxylic species of invertebrate, then clearfelling and slash-burning may cause a gradual extinction of an important element of the forest biota.     

Changes in carabid beetle diversity within a fragmented agricultural landscape

The distribution of carabid and cicindelid (Coleoptera: Carabidae) beetles in five distinct habitats (riparian, mature orchard, pine windbreak, young orchard, natural veld), within Tambuti Citrus Estate (Swaziland) was examined by pitfall trapping over 18 months. Habitats with high vegetation and litter cover had the highest species diversity and larger specimens, e.g. riparian border and pine windbreak, while the lowest diversity was observed in intensively managed mature citrus orchards. While species such as Tefflus delagorguei Guérin occurred in all the habitats sampled, certain species illustrated habitat specificity; e.g. Dromica ambitiosa Péringuey was observed only in the pine windbreaks while Haplotrachelus sp. Chaudoir occurred mainly in the vegetated riparian and natural veld habitats. Four unidentified carabid beetles were exclusive to the riparian border habitat. This habitat was the only one with a distinct assemblage of species in the agricultural mosaic studied. Multivariate analyses were used to assess the role of soil and environmental variables in relation to the ground beetle diversity within the agricultural mosaic studied.     

Effects of narrow roads on the movement of carabid beetles (Coleoptera,Carabidae) in Nopporo Forest Park,Hokkaido

Forest-dwelling carabid beetles that have no flight ability were studied using mark-recapture methods in late-June to mid-October 2007. This study was done to determine the effects of narrow roads in Nopporo Forest Park, Hokkaido on carabid beetle movement and habitat use. The investigation was conducted at four sites: one site was an abandoned grassy road with a width of 3.5 m, two sites were gravel roads with widths of 3.5 and 4.5 m, and another site was an asphalt-paved road with a width of 4.5 m. A total of 3,580 individuals from six species of carabid beetles were collected using dry pit-fall traps, and recapture rates ranged from 6.1 to 36.2%. All examined roads acted as barriers against the movement of Leptocarabus arboreus ishikarinus. All roads, except the abandoned grassy road, acted as a barrier against Carabus granulatus yezoensis movement. Forest–roadside verge comparisons demonstrated that some carabid beetles avoid even narrow roadside verges. Harmful effects increase with increasing road width and both paved roads and narrow roads negatively affect the movement of carabid beetles inhabiting the bordering forest. Therefore, forest specialist beetles are influenced by a barrier effect that starts at the forest road verge, and this barrier effect may be exacerbated by vehicular traffic. Therefore, these barrier effects on carabid beetles should be considered when planning and implementing road construction and maintenance in forests.     

Carabid Beetle and Spider Assemblages along a Forested Urban–Rural Gradient in Southern Finland

To investigate the effects of urbanization on carabid beetles (Carabidae) and ground dwelling spiders (Araneae) a study was completed along a 20km 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.     

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

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

Clonal organization of populations of Asarum europaeum and Maianthemum bifolium in contrasting woodland habitats

Populations of two rhizomatous species, Asarum europaeum (asarabacca) and Maianthemum bifolium (May lily), were examined in two, and four forest habitats respectively, in the Roztocze National Park (south-eastern Poland). May lily populations were studied in habitats: the Carpathian beechwood, upland mixed fir forest, subboreal moist mixed coniferous forest and bog-alder forest. Asarabacca was studied in two habitats: beechwood and Scots pine community (an 80-year-old plantation). In both the species studied intra- and inter-populational differences of the size of genets in terms of above- and below-ground parts of individuals as well as the biomass and area occupied were observed. In May lily populations the greatest mean number of shoots per genet was found in the fir forest (11.62±3.29), a value almost twice as great as that in the moist coniferous forest and nearly three times greater than in the bog-alder forest. Total rhizome length was also the greatest in the fir forest (351.9±98.7 cm) followed by moist coniferous forest, beechwood and alder forest habitats. In all populations of May lily a greater part of total dry weight biomass is in below-ground organs. The greatest biomass value of a genet was found in the fir forest (4.275 g), the smallest in the bog-alder forest (0.110 g). All populations differed significantly in terms of leaf area, leaf length (with the exception of fir forest and beechwood habitats where the values were the greatest), and leaf width (excluding moist coniferous and bog-alder forests which had the smallest values). In the case of asarabacca, both the mean number of ramets per genet (3.36±0.45 vs. 2.49±0.20) and total rhizome length (40.3±6.4 cm vs. 21.1±1.8 cm) were greater in the beechwood habitat than in the pine community. In the first population genets had 3–5 times greater the total biomass of those from the pine community. Only genets of the latter had proportionately more dry weight biomass in above-ground parts. It seems to be correlated with greater rhizome dieback and disintegration of genets into smaller units. Both populations were significantly different in terms of all examined parameters of leaves. Genets of both the species studied were found to have their own structure of developmental phases that often differed for shoots and rhizomes.     

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

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

Changes in ant communities along an age gradient of cocoa cultivation in the Oumé region,central Côte d'Ivoire

We identified the extent to which ant diversity occurs despite conversion of forests into cocoa plantations by examining the communities across four age classes of plantations (classes I–IV with increasing age from 0–5 to 21–40 years) and in their original forests. An extensive sampling protocol consisting of pitfall trapping, leaf litter sampling, soil sampling and hand sampling was used to characterize ant species richness and composition in three replicates of each age class and in the remaining forest patches. A total of one hundred ant species was found in all habitats combined. While the forest was the richest habitat (73 species), species richness in the different plantation age classes varied as follows (sorted in descending order): class IV (69 species) > class III (57 species) > class I (52 species) > class II (43 species). Age gradient was thus significantly positively correlated with mean species richness and with the relative abundance of some subfamilies. The species composition differed greatly between some plantation age classes and the forest. The two youngest cocoa age classes (I and II) were most dissimilar to the forest. In contrast, forest ants were well represented in the old cocoa age classes (III and IV). Three functional guilds (generalist predators, specialist predators and territorially dominant arboreal species) were in their relative abundance significantly correlated to the age gradient. Overall, cocoa cultivations retaining a floristically diverse and structurally complex forest structure are a suitable management system for the conservation of ant species of the formerly forested habitats.     

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

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

Habitat Specificity and Variation of Coleopteran Assemblages Between Habitats in a Southern African (Swaziland) Agricultural Landscape

Assessment of Coleopteran diversity and abundance was carried out in the lowveld region of Swaziland by pitfall trapping in five distinct habitats. Additionally, the study was to ascertain if any of the families collected illustrated habitat fidelity. 18 coleopteran families, comprising 2903 individuals were collected, with an additional 29 unidentified specimens, totalling 2932 beetles. Numerically, the top five families were the Scarabaeidae (2425), Carabidae (211), Tenebrionidae (149), Nitidulidae (37) and Curculionidae (22). 66.6% of all specimens collected were harboured within the pine windbreak while the lowest number (2.6%) was collected from the mature citrus orchard. The highest proportion (77%) of scarabaeid beetles collected occurred within the pine windbreak. Habitat specificity was illustrated by one family, Meloidae, which was found only in the young orchard. Community analysis was further carried out to ascertain distribution patterns of the dominant coleopteran families. Three scarabaeid species were found only in the pine windbreak while three carabid species occurred only in the indigenous savanna. Significant differences between habitats were observed in the number of beetles collected while no significant differences were observed in terms of the number of families observed in each habitat (p<0.05). Results indicate that conservation of the various habitat patches within the mosaic studied could facilitate conservation of whole communities rather than individual species thus facilitating effective conservation of the agricultural landscape.     

The effects of forestry on carabid beetles (Coleoptera: Carabidae) in boreal forests

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.