How does landscape context contribute to effects of habitat fragmentation on diversity and population density of butterflies?

Aim Studies on habitat fragmentation of insect communities mostly ignore the impact of the surrounding landscape matrix and treat all species equally. In our study, on habitat fragmentation and the importance of landscape context, we expected that habitat specialists are more affected by area and isolation, and habitat generalists more by landscape context. Location and methods The study was conducted in the vicinity of the city of Göttingen in Germany in the year 2000. We analysed butterfly communities by transect counts on thirty‐two calcareous grasslands differing in size (0.03–5.14 ha), isolation index (2100–86,000/edge‐to‐edge distance 55–1894 m), and landscape diversity (Shannon–Wiener: 0.09–1.56), which is correlated to percentage grassland in the landscape. Results A total of 15,185 butterfly specimens belonging to fifty‐four species are recorded. In multiple regression analysis, the number of habitat specialist (n = 20) and habitat generalist (n = 34) butterfly species increased with habitat area, but z‐values (slopes) of the species–area relationships for specialists (z = 0.399) were significantly steeper compared with generalists (z = 0.096). Generalists, but not specialists, showed a marginally significant increase with landscape diversity. Effects of landscape diversity were scale‐dependent and significant only at the smallest scale (landscape context within a 250 m radius around the habitat). Habitat isolation was not related to specialist and generalist species numbers. In multiple regression analysis the density of specialists increased significantly with habitat area, whereas generalist density increased only marginally. Habitat isolation and landscape diversity did not show any effects. Main conclusions Habitat area was the most important predictor of butterfly community structure and influenced habitat specialists more than habitat generalists. In contrast to our expectations, habitat isolation had no effect as most butterflies could cope with the degree of isolation in our study region. Landscape diversity appeared to be important for generalist butterflies only.     

Trait-Specific Responses of Wild Bee Communities to Landscape Composition,Configuration and Local Factors

Land-use intensification and loss of semi-natural habitats have induced a severe decline of bee diversity in agricultural landscapes. Semi-natural habitats like calcareous grasslands are among the most important bee habitats in central Europe, but they are threatened by decreasing habitat area and quality, and by homogenization of the surrounding landscape affecting both landscape composition and configuration. In this study we tested the importance of habitat area, quality and connectivity as well as landscape composition and configuration on wild bees in calcareous grasslands. We made detailed trait-specific analyses as bees with different traits might differ in their response to the tested factors. Species richness and abundance of wild bees were surveyed on 23 calcareous grassland patches in Southern Germany with independent gradients in local and landscape factors. Total wild bee richness was positively affected by complex landscape configuration, large habitat area and high habitat quality (i.e. steep slopes). Cuckoo bee richness was positively affected by complex landscape configuration and large habitat area whereas habitat specialists were only affected by the local factors habitat area and habitat quality. Small social generalists were positively influenced by habitat area whereas large social generalists (bumblebees) were positively affected by landscape composition (high percentage of semi-natural habitats). Our results emphasize a strong dependence of habitat specialists on local habitat characteristics, whereas cuckoo bees and bumblebees are more likely affected by the surrounding landscape. We conclude that a combination of large high-quality patches and heterogeneous landscapes maintains high bee species richness and communities with diverse trait composition. Such diverse communities might stabilize pollination services provided to crops and wild plants on local and landscape scales.     

Local species immigration,extinction, and turnover of butterflies in relation to habitat area and habitat isolation

Temporal dynamics of insect communities in terrestrial habitat fragments have been rarely studied. Here it was tested whether immigration, extinction, and turnover of butterfly species change with area and isolation of 31 calcareous grasslands. The area ranged from 0.03 to 5.14 ha, the isolation index from 2,100 to 86,000 (edge-to-edge distance 55–1,894 m). In both study years (1996, 2000), the total number of individuals (16,466, 15,101) and species (60, 54) sampled across all sites were similar and number of species increased with area in both years indicating an equilibrium. Rates of extinction (38% for habitat specialists vs. 20% for generalists) and turnover (51% vs. 35%) were higher, and rates of immigration (11% vs. 30%) were lower for habitat specialists than for generalists. Extinction and turnover rates decreased with increasing fragment size for both specialist (n =25 species) and generalist (n =36) butterflies, but specialists showed a significantly steeper decrease with increasing fragment size than generalists. Immigration rates increased with area. As a result, species number of habitat specialists declined in small habitats but not in large habitats between 1996 and 2000. No significant impact of habitat isolation on the butterfly community was found. The data suggest that large habitat fragments are of special importance for the conservation of the specialized, most endangered butterfly species. Habitat isolation appears to be less important, as butterflies can cope with the habitat mosaic in our study region.Due to an error in the citation line, this revised PDF (published in December 2003) deviates from the printed version, and is the correct and authoritative version of the paper.     

After the hotspots are gone: Land use history and grassland plant species diversity in a strongly transformed agricultural landscape

Question: We asked how landscape configuration and present management influence plant species richness and abundance of habitat specialists in grasslands in a ‘modern’(much exploited and transformed) agricultural Swedish landscape. Location: Selaön, south‐eastern Sweden (59°24’ N, 17°10’ E). Methods: Present and past (150 and 50 years ago) landscape pattern was analysed in a 25 km² area. Species richness was investigated in 63 different grassland patches; grazed and abandoned semi‐natural grasslands, and grazed ex‐arable fields. Influence of landscape variables; area, past and present grassland connectivity, present management on total species richness, density and abundance of 25 grassland specialists was analysed. Results: Semi‐natural grasslands (permanent unfertilised pastures or meadows formed by traditional agricultural methods) had declined from 60% 150 years ago to 5% today. There was a significant decline in species richness and density in abandoned semi‐natural grasslands. Total species richness was influenced by present management, size and connectivity to present and past grassland pattern. Landscape variables did not influence species density in grazed semi‐natural grassland suggesting that maintained grazing management makes grassland patches independent of landscape context. The abundance of 16 grassland specialists was mainly influenced by management and to some extent also by landscape variables. Conclusion: Although species richness pattern reflect management and to some extent landscape variables, the response of individual species may be idiosyncratic. The historical signal from past landscapes is weak on present‐day species richness in highly transformed, agricultural landscapes. Generalizations of historical legacies on species diversity in grasslands should consider also highly transformed landscapes and not only landscapes with a high amount of diversity hotspots left.     

Tracking the effects of one century of habitat loss and fragmentation on calcareous grassland butterfly communities

Habitat loss and fragmentation are known to reduce patch sizes and increase their isolation, consequently leading to modifications in species richness and community structure. Calcareous grasslands are among the richest ecosystems in Europe for insect species. About 10% (1,150 ha) of the total area of a calcareous ridge region (Calestienne, Belgium) and its butterfly community was analysed over a timeframe of about 100 years. Since 1905 to present day (2005), the Calestienne region has undergone both calcareous grassland loss and fragmentation: not only did calcareous grassland size decrease and isolation increase, but also, the number of calcareous grassland patches within the landscape increased until 1965, and subsequently decreased, clearly reflecting the effects of fragmentation. These processes have had a profound effect on the butterfly community: extinction and rarefaction affected significantly more often specialist species, which means that generalist species are more and more overrepresented. This ecological drift, i.e. the replacement of specialists by generalists in species assemblages is likely to be a general effect of habitat loss and fragmentation on natural communities.     

Effects of Wildflower Strip Quality,Quantity, and Connectivity on Butterfly Diversity in a Swiss Arable Landscape

The effects of habitat restoration measures designated to promote farmland biodiversity have been documented at the field scale, but little is known about their role in restoring the agricultural mosaic. In this study, we analyzed the effects of wildflower strips (WFS) at the field scale and in the landscape context on butterflies in a Swiss arable landscape. Three hypotheses were tested: (1) butterfly diversity and abundance are higher in WFS than in conventional fields; (2) butterfly diversity and abundance are enhanced by the amount, proximity and connectivity of WFS in the landscape context; (3) additional factors influence butterfly diversity and abundance according to individual site conditions and landscape context characteristics linked to other landscape elements. WFS had more species and individuals of butterflies than conventional habitats. However, promoted species were mainly generalists; few specialists were enhanced. The diversity of all butterflies and of generalists increased linearly with percent cover of WFS, reflecting an effect of restoration measures depending on the landscape context. The influence of proximity and connectivity of WFS were, however, not significant. The occurrence of specialists was conditioned by plant species richness, while the effect of WFS for overall diversity was affected by the amount of grassland in the surroundings. We conclude that to increase the effectiveness of biodiversity‐orientated restoration measures, their implementation should be steered toward increasing the share of WFS in the landscape. However, the combination of WFS with additional restoration measures might be needed to halt the decline of specialist species.     

Dispersal capacity and diet breadth modify the response of wild bees to habitat loss

Habitat loss poses a major threat to biodiversity, and species-specific extinction risks are inextricably linked to life-history characteristics. This relationship is still poorly documented for many functionally important taxa, and at larger continental scales. With data from five replicated field studies from three countries, we examined how species richness of wild bees varies with habitat patch size. We hypothesized that the form of this relationship is affected by body size, degree of host plant specialization and sociality. Across all species, we found a positive species–area slope (z = 0.19), and species traits modified this relationship. Large-bodied generalists had a lower z value than small generalists. Contrary to predictions, small specialists had similar or slightly lower z value compared with large specialists, and small generalists also tended to be more strongly affected by habitat loss as compared with small specialists. Social bees were negatively affected by habitat loss (z = 0.11) irrespective of body size. We conclude that habitat loss leads to clear shifts in the species composition of wild bee communities.     

Do asynchronies in extinction debt affect the structure of trophic networks? A case study of antagonistic butterfly larvae–plant networks

Habitat loss and fragmentation affect species richness in fragmented habitats and can lead to immediate or time‐delayed species extinctions. Asynchronies in extinction and extinction debt between interacting species may have severe effects on ecological networks. However, these effects remain largely unknown. We evaluated the effects of habitat patch and landscape changes on antagonistic butterfly larvae–plant trophic networks in Mediterranean grasslands in which previous studies had shown the existence of extinction debt in plants but not in butterflies. We sampled current species richness of habitat‐specialist and generalist butterflies and vascular plants in 26 grasslands. We assessed the direct effects of historical and current patch and landscape characteristics on species richness and on butterfly larvae–plant trophic network metrics and robustness. Although positive species‐ and interactions–area relationships were found in all networks, structure and robustness was only affected by patch and landscape changes in networks involving the subset of butterfly specialists. Larger patches had more species (butterflies and host plants) and interactions but also more compartments, which decreased network connectance but increased network stability. Moreover, most likely due to the rescue effect, patch connectivity increased host‐plant species (but not butterfly) richness and total links, and network robustness in specialist networks. On the other hand, patch area loss decreased robustness in specialist butterfly larvae–plant networks and made them more prone to collapse against host plant extinctions. Finally, in all butterfly larvae–plant networks we also detected a past patch and landscape effect on network asymmetry, which indicates that there were different extinction rates and extinction debts for butterflies and host plants. We conclude that asynchronies in extinction and extinction debt in butterfly–plant networks provoked by patch and landscape changes caused changes in species richness and network links in all networks, as well as changes in network structure and robustness in specialist networks.     

Impacts of weeping lovegrass (<Emphasis Type="Italic">Eragrostis curvula</Emphasis>) invasion on native grasshoppers: responses of habitat generalist and specialist species

We investigated invasion impacts of a grass species (Eragrostis curvula) on native grasshoppers by periodic censuses of these insects on gravelly floodplains of the Kinu River, Japan. Our hypothesis was that there are greater impacts on natives when they are habitat specialists, as opposed to habitat generalists. The study area comprised two main habitat types: gravelly areas and riparian grasslands. Among 12 grasshopper species identified, five were more abundant in one of the habitat types and all of them were significantly negatively affected by coverage of weeping lovegrass, whereas seven occurred at the both habitat types simultaneously and a significantly smaller portion of species (two of the seven) was negatively affected by the alien plants. The results suggest that habitat specificity is related to the grasshopper species’ sensitivity to the plant, indicating that habitat specialist herbivores living on open gravelly floodplains are likely highly vulnerable to this plant invasion.     

Do forest plants conform to the theory of island biogeography: the case study of bog islands

Biodiversity conservation is confronted with increasing risk of extinction in isolated small-area remnants and the limitation of species to colonize recently formed habitats. We hypothesized that the equilibrium pattern of forest herb layer in long-term fragmented landscape should comply with the theory of island biogeography. Forests on mineral soil islands located in large mires of western Estonia were considered as dispersal target habitats, and forests on mainland and peninsulas in mires as sources. Species richness was the lowest in mainland forests and the effect was confounded by habitat structure, suggesting a negative effect of silvicultural management in easily accessible forests. We observed the ‘small island effect’, i.e. greater overall species richness in small-area habitats, which was determined by the habitat preference of shade tolerant generalists. The average species richness of common mainland forest specialists varied little, but capitalizing on the traditional approach and analyzing only island data, weak effects of distance and habitat quality were detected. At single species level, unexpectedly, many habitat specialists were observed to have successfully dispersed to islands, indicating insufficient knowledge of the long-distance dispersal mechanisms of forest-dwelling plants. In fragmented forest landscapes the theory of island biogeography can be applied to habitat specialist plant species, but only regarding the effect of isolation and in conditions of persistent forest structural quality. In the light of global changes, optimized conservation planning should primarily target on (i) the conservation of ancient habitat fragments independent of their current area, and (ii) the promotion of diversity of potential dispersal vectors in the landscape.     

The interplay between local and landscape scales on the density of pond-dwelling anurans in subtropical grasslands

We investigated the role of local and landscape environmental variables on anurans density classified as habitat specialists and generalists in grassland landscapes, known as South Brazilian grasslands (SBG). In this region, we surveyed 187 ponds distributed over 40 landscape sampling units. For each pond, 31 local environmental variables were measured. Each landscape sampling unit was embedded within a larger regional sampling unit with different landscape properties. For each landscape and regional sampling units, 16 landscape metrics were extracted from a land cover and use map. We recorded 35 species, eleven of which are specialists in the SBG. The specialists were affected by 11 local and 2 landscape environmental variables, while generalists were affected by 14 local and one landscape environmental variable. Thus, specialists and generalists presented different relationships with local and landscape variables, but in general local variables had a greater influence on the density of anurans than the landscape variables. However, the landscape indirectly influenced local variables because higher quality ponds were in landscapes with higher percentages of natural habitat. In conclusion, reproductive sites with higher local quality and located within landscapes with higher percentages of natural grasslands are essential to conserve anurans in this habitat. Effective conservation of such sites would benefit from further studies that assess effects of land use and biotic integrity of ponds, which can help to determine (a) the relative effects of local habitat quality of ponds and (b) the effectiveness of protecting ponds and their local surroundings for anuran conservation in SBG. Abstract in Portuguese is available with online material.     

Species richness of vascular plants, bryophytes and lichens in dry grasslands: The effects of environment, landscape structure and competition

We studied the relative importance of local habitat conditions and landscape structure for species richness of vascular plants, bryophytes and lichens in dry grasslands on the Baltic island of Öland (Sweden). In addition, we tested whether relationships between species richness and vegetation cover indicate that competition within and between the studied taxonomic groups is important. We recorded species numbers of vascular plants, bryophytes and lichens in 4 m² plots (n=452), distributed over dry grassland patches differing in size and degree of isolation. Structural and environmental data were collected for each plot. We tested effects of local environmental conditions, landscape structure and vegetation cover on species richness using generalized linear mixed models. Different environmental variables explained species richness of vascular plants, bryophytes and lichens. Environmental effects, particularly soil pH, were more important than landscape structure. Interaction effects of soil pH with other environmental variables were significant in vascular plants. Plot heterogeneity enhanced species richness. Size and degree of isolation of dry grassland patches significantly affected bryophyte and lichen species richness, but not that of vascular plants. We observed negative relationships between bryophyte and lichen species richness and the cover of vascular plants. To conclude, effects of single environmental variables on species richness depend both on the taxonomic group and on the combination of environmental factors on a whole. Dispersal limitation in bryophytes and lichens confined to dry grasslands may be more common than is often assumed. Our study further suggests that competition between vascular plants and cryptogams is rather asymmetric.     

The role of patch area and habitat diversity in explaining native plant species richness in disturbed suburban forest patches in northern Belgium

Relatively easy measurable patch characteristics (especially habitat diversity measures) have proven to be valuable indicators of forest plant species richness in forest fragments of relatively undisturbed areas. Urban and suburban forest patches, however, are characterized by a specific landscape ecological context implying that specific processes may influence ecosystem functioning and hence that other abiotic indicators for plant diversity are more appropriate. We studied the relation between functional ecological plant species groups and suburban forest patch characteristics such as patch area, habitat diversity and isolation. Some components of species richness were related to the isolation of the patches. In contrast to previous similar large-scale fragmentation studies in more rural areas, further results stressed the overwhelming importance of patch area relative to habitat variables in determining species richness. This suggests (1) the occurrence of density-dependent species extinction processes in small forest patches; or (2) the existence of external deterministic factors which put a major constraint on species richness in small patches. We tend to support the latter hypothesis and propose forest disturbance and associated black cherry (Prunus serotina Ehrh.) invasion as such a possible external factor. Small forest patches may be more sensitive to disturbance and biological invasion due to various reasons. Hence large forest patches are to be preferred for plant conservation in the suburban area.     

Invertebrate herbivory along a gradient of plant species diversity in extensively managed grasslands

Increasing plant diversity has long been hypothesized to negatively affect levels of invertebrate herbivory due to a lower number of specialist insect herbivores in more diverse sites, but studies of natural systems have been rare. We used a planned comparison to study herbivory in a set of 19 semi-natural montane grasslands managed as hay meadows. Herbivory was measured in transects through the plant communities, and in individuals of Plantago lanceolata and Trifolium pratense that were transplanted into each meadow. In addition, plant community biomass and arthropod abundances were determined in the grasslands. Before the first mowing in June, mean herbivory levels correlated negatively with plant species richness, as predicted by theory, but they were also significantly affected by plant community biomass and plant community composition. After mowing, herbivory levels were only significantly related to plant community composition. Damage levels in the transplants were lower than herbivory levels in the established plant communities. Most insect herbivores were generalists and not specialists. The number of insect herbivores and spiders were positively correlated and tended to increase with increasing plant species richness. Herbivory levels were correlated negatively with spider abundances. We conclude that while the predicted negative relationship between plant species richness and insect herbivory can be found in grasslands, the underlying mechanism involves generalist rather than specialist herbivores. Our data also suggest a role of natural enemies in generalist herbivore activities.Electronic Supplementary Material Supplementary material is available to authorised users in the online version of this article at .     

Soil phosphorus availability determines the contribution of small,individual grassland remnants to the conservation of landscape-scale biodiversity

Questions

Small, remnant habitats embedded in degraded, human-dominated landscapes are generally not a priority in conservation, despite their potential role in supporting landscape-scale biodiversity. To warrant their inclusion in conservation management and policy, we question under which conditions they may exhibit the largest conservation value.

Location

Nine landscapes spread across the counties of Stockholm and Södermanland, Sweden.

Methods

Per landscape, plant communities were surveyed in 6 and 12 1 × 1 m² plots across large, intact semi-natural grasslands and small remnant grasslands, respectively. These two contrasting grassland types served as a model system. A topsoil sample was taken in each plot to determine habitat quality in terms of soil pH, plant-available P, and C:N ratio. We used a joint species distribution model to analyse the extent to which grassland type and habitat quality define and predict resident community diversity and composition, including whether they support grassland specialists.

Results

At the landscape scale, the combined remnant grasslands sustained diverse plant communities which did include a significant subset of habitat specialists. Yet, the contribution of individual remnants clearly varied with local-scale habitat quality; soil phosphorus availability lowered plot-level species richness, mostly by constraining the occurrence of grassland specialists. Semi-natural grassland communities were comparatively insensitive to variation in soil phosphorus availability.

Conclusions

The combined habitat amount and the significant number of habitat specialists sustained by remnant grasslands with high habitat quality, shows they can represent a valuable resource to support landscape-scale biodiversity conservation. This offers no wildcard to neglect the continued biotic and abiotic threats on semi-natural grassland plant diversity such as chronic and accumulating P eutrophication, discontinuation of management or poor matrix permeability, as semi-natural grasslands harbour the majority of habitat specialists, while sourcing surrounding remnant grassland communities.

     

Species Richness, Community Specialization and Soil-Vegetation Relationships of Managed Grasslands in a Geologically Heterogeneous Landscape

The increasing importance of the conservation value of managed grasslands has led to many studies exploring edaphic determinants of grassland biodiversity. Most studies, however, come either from very large areas, where biogeographical factors such as dispersal limitation may play a role, or from small, but ecologically rather uniform, regions. In addition, few studies further distinguish between plant specialists and generalists in the interpretation of the observed patterns. Here we studied species richness in semi-natural, managed grasslands in the Strá?ovské vrchy Mountains in the West Carpathians, Slovakia, where there is a matrix of different bedrocks (crystalline, sandstone, claystone, limestone) on a steep altitudinal gradient. In 89 vegetation plots we sampled the species composition of vascular plants and bryophytes and measured soil chemistry, slope angle, heat index, altitude and soil depth. We further applied Ellenberg indicator values and classified species into community specialists or generalists based on the analysis of a large phytosociological database. Using cluster analysis, we delimited five vegetation types that clearly differed in response to soil characteristics. Species richness varied between 19 and 64 species per 16?m². The main compositional gradient correlated with measured soil pH and calcium, but species richness was not significantly correlated with these factors. Soil available phosphorus was not associated with species composition as has been found elsewhere, but it did correlate negatively with species richness and the richness of specialists. Overall, species richness was largely driven by the number of specialists in the plot and particular vegetation types differed conspicuously in their number. We further found significant effects of iron, potassium and sodium on species richness, species composition and the representation of specialists and generalists. Our results provide new insights into the determinants of diversity in managed grasslands as well as to the theoretical species pool concept, explaining species richness variation along a pH gradient.     

垫状植物囊种草对群落物种多样性的影响

在甘肃盐池湾国家级自然保护区内海拔4137 m处,选择典型的囊种草垫状植被设置研究样地,研究了垫状植物囊种草对群落物种组成和群落物种多样性的影响,并且定量的研究了囊种草对群落物种丰富度的影响能力和维持潜力。研究结果表明:囊种草为群落中增加了新的植物种类,并且提高了部分生境一般种的多度;囊种草的出现提高了群落物种密度和物种丰富度,进而提高了群落物种多样性;囊种草斑块的增加将会引起景观水平物种丰富度的增加,表明囊种草具有为群落中引入新的植物种类进而提高群落物种丰富度的能力;在景观水平,囊种草所创造的生境多样性则成为一种保障,可以维持景观中物种丰富度从而降低物种损失的风险,表明囊种草具有较高的群落物种丰富度维持潜力。     

Neotropical savanna ants show a reversed latitudinal gradient of species richness,with climatic drivers reflecting the forest origin of the fauna

Aim

To evaluate the extent to which ant species richness in Neotropical savannas varies with macrogeographic variables, and to identify the potential climatic drivers of such variation.

Location

The Cerrado savanna biome of central Brazil, in a region spanning ca. 20° of latitude and 18°of longitude.

Methods

Standardized sampling of the arboreal and ground‐dwelling faunas was performed in 29 well‐preserved savanna sites using pitfall traps. Species were classified according to their habitat affinities: open‐savanna specialists, forest‐associated species or habitat generalists. We used generalized linear models to evaluate the importance of geographic (latitude, longitude and elevation) and climatic (mean temperature and three metrics of rainfall) variables as predictors of species richness.

Results

The total number of species recorded at each site varied more than twofold (from 59 to 144), and latitude was the best geographic correlate of overall species richness. However, contrary to the expected pattern, more species were found at higher than lower latitudes. This reversed latitudinal pattern of diversity occurred for both the arboreal and ground‐dwelling faunas, and for the habitat generalists and forest specialists. The savanna specialists showed a mid‐latitudinal peak in diversity. Overall, there was a significant positive association between rainfall and species richness, but the strength of this relationship varied with ant habitat affinity.

Main conclusions

The Cerrado ant fauna shows a reverse latitudinal gradient in species diversity, and this can be explained by increasing rainfall during the warmest months of the year (and therefore in plant productivity) with increasing latitude. The sensitivity of Cerrado ant diversity to declining rainfall contrasts with the high resilience to aridity of the Australian savanna ant fauna, and this reflects the contrasting evolutionary histories of these faunas. Our findings highlight the importance of historical processes as drivers of intercontinental contrasts in macroecological patterns.     

Fragmentation in calcareous grasslands: species specialization matters

Habitat fragmentation resulting from anthropogenic land-use change may negatively affect both biodiversity and ecosystem structure and function. However, susceptibility to fragmentation varies between species and may be influenced by for instance specialization, functional traits and trophic level. We examined how total and specialist species richness, species composition and functional trait composition at two trophic levels (vascular plants and sap-feeding hoppers) vary with habitat fragmentation (patch size and connectivity) in dry calcareous grasslands in southeast Norway. We found that fragmentation affected plant and hopper species composition both totally and of habitat specialists, but with a net species loss only for the specialists, indicating greater susceptibility of specialized species. Reductions in patch size and increasing isolation negatively affected plant specialists with different sets of traits, effectively reducing the number of species with trait combinations suitable to persist in small and isolated patches. Fragmentation influenced trait composition of the total hopper community, but not of habitat specialists. A lesser degree of habitat association could explain why hoppers, despite belonging to a higher tropic level, seemed to be less susceptible to fragmentation than plants. Nonetheless, our study shows that habitat fragmentation affects both species richness, species composition and trait composition of plants and hoppers, indicating that fragmentation leads not only to a loss of species, but also alters dominance hierarchies and the functionality of grassland communities.