Partitioning of arthropod species diversity in temperate meadows,wildflower areas and pastures

To counteract the rapidly ongoing species decline in modern agroecosystems, most European countries have developed and adopted agri-environment schemes. The efficiency of these schemes, however, ranges from successful to nearly ineffective. To estimate the efficiency of the Swiss agri-environment scheme in particular, we investigated the contribution of extensively managed pastures and meadows and wildflower areas to beetle, heteropteran bug and spider diversity. Extensively managed meadows were shown to contribute most to landscape-scale richness (highest species richness for beetles and bugs), followed by wildflower areas (bugs). Meadows harboured approximately twice as many beetle species unique to this habitat type than wildflower areas and pastures. Bug species unique to a specific habitat type were similar between meadows and wildflower areas, but much lower (approximately 30%) in pastures. To increase beetle species richness, extensively managed meadows should be represented more often in the landscape because meadows harboured the highest number of species and most uniquely found species. To increase species richness of true bugs, both meadows and wildflower areas should be represented more often in the landscape because they harboured more species and more uniquely found species compared to pastures. Across arthropod taxa and habitat types, β diversity was more important for γ diversity than α diversity, indicating that distinctiveness, rather than within-site diversity, was key in determining the contribution of sites to γ (landscape) diversity. This substantiates the argument that increasing the number of sites is efficient to increase landscape species richness. The turnover component of β diversity was far more important than the nestedness component for all arthropod taxa and habitat types and accounted for 79.0% to 95.4% of total β diversity. In conclusion, extensively managed meadows and wildflower areas should be particularly promoted by the Swiss agri-environment scheme, as they contributed more to landscape species richness and species uniqueness than pastures.     

What can sown wildflower strips contribute to butterfly conservation?: an example from a Swiss lowland agricultural landscape

The objective of this study was to compare butterfly abundances and diversity between wildflower strips and extensively used meadows to identify which butterfly species can be supported by establishing wildflower strips. Butterflies were recorded along transects during one season in twenty-five sown wildflower strips and eleven extensively used meadows in a Swiss lowland agricultural landscape (600 ha). In total 1,669 butterflies of 25 species were observed (25 in the strips, 18 in meadows). This can be related to 38 species recorded in the region (lowland part of Kanton Fribourg) within the Swiss Biodiversity Monitoring Programme. In wildflower strips the number of butterflies per transect meter was significantly higher than in the meadows, but there was no significant difference in species richness. Butterfly communities, though, were quite different between the two habitat types. Habitat type, abundances of flowering plants and presence of forest within 50 m were identified as factors influencing butterfly species richness. Butterfly abundances were affected by habitat type and abundance of flowering plants. In wildflower strips, 65% of all flower visits by butterflies were observed on Origanum. It can be concluded that sown wildflower strips can support a substantial part of a regions species pool. This is mostly true for common species, but can apply to rare species when, for example, larval food plant requirements are met.     

Staphylinidae and Carabidae overwintering in wheat and sown wildflower areas of different age

Species richness and abundance of staphylinid and carabid beetles overwintering in winter wheat fields and 1- to 3-year-old wildflower areas were investigated during 2000/2001 on 16 study sites in Switzerland. Abundance and species richness of overwintering staphylinids significantly increased with successional age of the wildflower areas and were always higher in older wildflower areas than in winter wheat. A similar but less distinct pattern was observed for the abundance and species richness of carabid beetles. The influence of habitat parameters (vegetation cover, fine sand content, organic matter, pH, soil pore volume, surrounding landscape structure, habitat area) on the staphylinid and carabid assemblages based on the number of individuals per species and site was analysed using canonical correspondence analysis. Vegetation cover was the most significant parameter significantly characterizing both staphylinid and carabid assemblages. The amount of vegetation cover explained 15.7% of the variance, fine sand content accounted for 13.3% and surrounding landscape structure for 10.9% of the variance in the staphylinid assemblage. In the carabid assemblage, vegetation cover was the only significant factor, explaining 24.7% of the variance. This study showed for the first time that the significance of wildflower areas as a reservoir for hibernation for generalist predatory beetles increases with progressing successional age.     

农田及生态补偿区甲虫群落结构的差异

为了调查冬麦田和不同年龄生态补偿区甲虫群落结构和物种多样性,从2003年7到10月和2004年5到6月在瑞士农业区周围不同景观中进行了实地调查,并采用对应及典范对应分析方法,对冬麦田和1~4a不同年龄阶段的野花地中的甲虫群落结构及物种多样性进行了比较系统的研究。结果,共捕甲虫6009只,分别属于150种,25科,其中,麦田共计38种445个体,1~4a不同年龄的野花地中分别计46种,2760个体,81种,1325个体,73种,668个体,75种,811个体。根据食性,植食性种类有98种(65.33%),5189个体(86.35%)、肉食性种类有40种(26.67%),240个体(3.99%)、食菌性种类有10种(6.67%),578个体(9.62%)、食腐性种类有2种(1.33%),2个体(0.03%)。冬麦田中栖息的甲虫种类及其物种丰富度和多度与1~4a不同年龄阶段的野花地有明显差异。这主要由于冬麦田中植物种类多样性低和植被结构简单而导致的。在不同演替阶段野花地中甲虫群落物种的丰富度一般在1~3a型野花地之间有差异。1年型野花地具有比较典型的甲虫群落结构,不同演替阶段的野花地对甲虫群落的定居,扩散及其演替过程中具有非常重要的作用。对甲虫提供丰富的食物资源和栖息,繁殖场所。因此,人为在农业区建立生态补偿区,有利于提高无脊椎动物和昆虫多样性,对物种保护方面具有重要意义。     

Grassland management for meadow birds in the Netherlands is unfavourable to pollinators

Agricultural intensification and loss of semi-natural grassland have contributed to biodiversity decline, including pollinator species, in pastures around the world. To reverse the decline, agri-environmental schemes have been implemented, varying widely in effectiveness. In addition, many countries, including the Netherlands, have established nature reserves in which semi-natural grasslands are restored and are often managed for specific groups of species, e.g. meadow birds or plants. The effects of such measures on insect biodiversity are not well known but recent reports on the dramatic decline of insect biomass in nature reserves have put even more attention to the impact of land use and management on biodiversity. This study compares pollinator abundance and species richness in three common semi-natural grassland management types in the Netherlands: (1) hay meadows, (2) herb-rich grasslands and (3) meadow bird grasslands. Pollinator abundance and species richness were assessed in eleven study areas, each with all three management types present. Standardized transects, insect sampling within a standard 20 min time frame and plot-based flower surveys were used in spring and summer to assess the relationships between management regime, floral abundance and diversity and pollinator communities. The results show that meadow bird grasslands have lower pollinator abundance and diversity and a less unique pollinator assemblage than both other types. Moreover, flower abundance has a positive effect on pollinator abundance and flower diversity has a positive effect on pollinator species richness. These results indicate that meadow-bird grasslands are a comparatively unfavourable habitat for bees, hoverflies and butterflies, which may be explained by a lack of flowers as well as unsuitable mowing practices. Measures benefitting both insectivorous birds and flower-visiting insects, such as rotational mowing, could remediate this imbalance.     

The effects of grassland management and aspect on Orthoptera diversity and abundance: site conditions are as important as management

Calcareous grasslands represent local hotspots of biodiversity in large parts of Central and Northern Europe. They support a great number of rare species which are adapted to these xerothermic habitats. Due to massive changes in land use, calcareous grasslands have become a rare habitat type and their conservation has been given a high priority in the habitats directive of the European Union. It is well known that grassland management may affect biodiversity substantially. However, the quality of calcareous grasslands is also influenced by abiotic conditions, such as aspect (i.e. sun exposure), which affects the local mesoclimate. We studied the combined effects of aspect and grassland management on Orthoptera diversity on 16 sites in Central Germany, in an unbalanced crossed design with three factors: aspect, management type and management intensity. For both response variables (diversity and abundance) we obtained a similar pattern. South-facing pastures maintained a greater diversity than north-facing pastures, but both had a greater diversity than extensively used meadows. Intensively used meadows maintained the lowest diversity and abundances. A multivariate analysis revealed that the abundance of rare Orthoptera species correlated with bare ground cover and forb cover, both of which were greatest at south-facing pastures. Our results suggest that grazing is a more suitable management for maintaining a high biodiversity in calcareous grasslands than mowing. Moreover, the mesoclimate (in this studied measured by its surrogate: aspect) is a crucial factor determining species richness and needs to be considered in reserve planning.     

Influence of abandonment on syrphid assemblages in mountainous meadows

Grasslands are often managed with different intensities in the European Alps. Studies have shown that a medium management can benefit plant and animal biodiversity in these ecosystems. However, in recent decades abandonment of extensively managed meadows is an ongoing global challenge. Syrphids (hoverflies) have been recognized as a threatened group due to environmental drivers, and these managed grasslands provide preferred habitats for them. Yet, at what extent syrphids respond to grassland management strategies is little known. We investigated whether abandonment of managed mountain meadows (mown once a year, no fertilizer use) affects syrphid abundance, richness and species assemblages. Moreover, the influence of plant richness, flower frequency and surrounding landscape on syrphids were assessed. Four managed meadows were compared with four abandoned meadows in a mountainous region in Austria. Adult syrphids were sampled over two consecutive years (June and August 2015–2016) by sweep netting using line transects and observation plots. Syrphid abundance was significantly higher in managed than abandoned meadows and increased with increasing plant richness and flower frequency across management types. Management and sampling time also significantly affected syrphid species assemblages. Syrphid richness and abundance were not influenced by surrounding landscape. We conclude that both abandoned and managed meadows provide important habitat types for syrphids. Therefore, efforts should be made to maintain both managed and abandoned meadows in order to protect syrphid species within mountainous landscapes.     

Plant diversity declines with recent land use changes in European Alps

Against a background of increasing land use intensification on favorable agricultural areas and land abandonment on less arable areas in the Alps, the aim of this investigation was to detect whether and how 10 differently used types of grassland can be distinguished by site factors, plant species composition, and biodiversity. By using a very large number of vegetation surveys (936) that were widely distributed in the Central Alps, site parameters and species composition of the different land use types were compared by discriminant analyses and various biodiversity indices. Results showed that land use is a significant factor affecting the development of different grassland communities with site factors playing a subordinate, yet important role. The 10 land use types studied can be clearly differentiated from one another by single species as well as by species composition. Our study found that the number of plant communities along with the number of species decreases constantly and significantly with increasing land use intensity and on abandoned land. For example, on average, extensively used meadows have more than three times as many species as intensively used meadows. Further, the most even distribution of species (Evenness index) is reached in intensively used meadows, whereas on pastures and abandoned land, some species become dominant forcing other species to recede. The results confirm that due to current trends in agriculture, such as land abandonment and land use intensification, plant diversity in the Alps is decreasing considerably.     

Amphibian species and functional diversity as indicators of restoration success in tropical montane forest

Tropical forest restoration is increasingly seen as an activity that may counteract or reduce biodiversity loss. However, few studies monitor fauna or consider measures of functional diversity to assess restoration success. We assessed the effect of a tropical montane forest restoration program on species and functional diversity, using amphibians as the target group. We compared amphibian assemblages in three types of land use: restoration areas, tropical montane cloud forest (TMCF; reference ecosystem) and cattle pastures (degraded ecosystem) in southern Mexico. We also described microclimate, microhabitat heterogeneity, woody vegetation structure and diversity for each type of land use, and their relationship to amphibian species and functional diversity. Compared to TMCF, restoration areas had similar environmental conditions. However, amphibian species richness was similar in the three types of land use and abundance was lower in the restoration areas. In TMCF, the amphibian assemblage was dominated by forest-specialist species, the pastures by generalist species, and the restoration areas by a combination of both species types. Interestingly, functional richness, functional evenness and functional divergence did not vary with land use, though the number of functional groups in restoration areas and TMCF was slightly higher. Overall, the results suggest that after seven years, active restoration provided habitat heterogeneity and recovered woody vegetation capable of maintaining amphibian species and functional groups similar to those inhabiting TMCF. Forest fragments adjacent to restoration areas seem to facilitate fauna recolonization and this emphasizes the importance of the conservation of the reference ecosystems to achieving restoration success.     

Phylogenetic and functional relationships in pastures and meadows from the North Adriatic Karst

Probably due to its phytogeographic position, the grasslands in the North Adriatic Karst are among the richest grasslands in the world and harbour the highest small-scale density of plant species found in terrestrial habitats. Different moisture and soil conditions determine distinct vegetation types, such as meadows, composed by mesophyllous plants and on mesic conditions, and semi-natural pastures, composed by sclerophyllous plants and on oligotrophic conditions. Even though plants in these two vegetation types differ in some of their attributes, their functional and phylogenetic relationships remain to be tested. We used a dataset comprising 180 species, in which 48 plots in the meadows and 52 plots in the pastures had been sampled, and tested the phylogenetic and functional relationships between the two vegetation types. The pastures contained more original species, but both the pastures and the meadows are expected to be important to increase biodiversity at landscape level. Different community assembly processes occurred in the two vegetation types, with limiting similarity leading to functional overdispersion in the meadows and environmental filtering leading to functional clustering in the pastures. Overall, traits were convergent, leading to a clustered phylogenetic structure in the meadows, probably due to pair-wise competition, and an overdispersed phylogenetic structure in the pastures, where species from different clades were filtered by the oligotrophic conditions. Transhumance may have contributed to the random pattern of trait diversity we found across the nodes of the phylogenetic tree.     

Attractiveness of sown wildflower strips to flower-visiting insects depends on seed mixture and establishment success

Establishing wildflower strips has been suggested as an effective measure to promote pollination services, pest control or general insect biodiversity, but little is known about the integration of these different objectives when selecting flower seed mixtures. In ten agricultural landscapes in the Netherlands, we established a wildflower strip (0.4 – 4.9 ha) with half of each strip sown with a mixture targeting longer-tongued pollinators and the other half sown with a mixture targeting shorter-tongued pollinators and natural enemies. We determined establishment success of sown wildflowers and evaluated the attractiveness of the established flower communities to multiple functional groups of flower visitors: bumblebees (long-tongued pollinators), hoverflies (short-tongued pollinators and natural enemies), and butterflies and total flower-visitor richness (indicators of wider biodiversity values). Bumblebees clearly preferred the pollinator-targeted seed mixture and were positively associated with cover of Fabaceae and negatively with Apiaceae. Hoverflies consistently preferred the natural enemy mixture and were positively associated with Apiaceae. The other target groups displayed no clear responses to seed mixture type but instead were associated with local flower richness within strips. Across sites, responses of flower-visitors to sown mixture types did not depend on wildflower strip size, proportion of surrounding semi-natural habitat, or flower variables. However, all flower-visitors except butterflies increased with increasing established cover or richness of (sown) flower species across sites. Our results suggest that, although species-rich wildflower strips may benefit several species groups, maximising different objectives involves trade-offs between functional groups that prefer short- or long-corolla flowers. Furthermore, our study suggests that sowing a wildflower mixture does not necessarily result in a vegetation with the same composition as the seed mixture as species may establish poorly or not at all. Selection of flower species for seed mixtures should therefore, in addition to insect target group, take the establishment characteristics of plant species into account.     

A multi-site experiment to test biocontrol effects of wildflower strips in different French climate zones

Sowing of wildflower strips has been integrated in agri-environment schemes of several European countries. Their beneficial effects on natural enemies of pest insects are well documented but (1) the desired spill-over into crop fields has not always been demonstrated, and (2) the need to adapt sown mixtures to regional climatic differences has been rarely addressed.We set up a multi-site experiment in different French climatic regions to compare effects of a wildflower strip with a grass mixture and spontaneous vegetation. The design included five regions, three to five fields per region and the three strip treatments being repeated in each field. We tested strip treatment effects on vegetation (plant species richness, plant and flower cover) and on natural enemies (hoverflies, ladybirds, aphid predation). In a subset, we further analysed the spill-over into winter wheat fields including natural enemies and pest insects (cereal aphids, leaf beetles).The wildflower strip mixture developed well in all regions and increased plant species richness and flower cover compared with grass strips and spontaneous vegetation. We found a corresponding higher hoverfly abundance and aphid predation in wildflower strips that were consistent in all regions, whereas ladybird abundance was not affected. A significantly higher hoverfly abundance, aphid predation and aphid parasitism in wheat fields close to wildflower strips indicated a spill-over. No corresponding margin treatment effects were observed for aphid and leaf beetle abundance in the field. A multivariate analysis comparing the influence of climate and vegetation parameters showed that floral cover better explained variation in natural enemy abundance and predation than climate. Our results demonstrated that similar mixtures of native plants can be used over large climatic gradients to improve biocontrol. Further research is needed to improve spill-over into crop fields and to obtain consistently strong effects in different climate zones.     

Wild bees respond complementarily to ‘high-quality’ perennial and annual habitats of organic farms in a complex landscape

Agricultural intensification leads to large-scale loss of habitats offering food and nesting sites for bees. This has resulted in a severe decline of wild bee diversity and abundance during the past decades. There is an urgent need for cost-effective conservation measures to mitigate this decline. We analysed the impact of five different high-quality habitats on species richness and abundance of wild bees in a complex landscape of north-western Switzerland at six sites. The five habitat types included 45 plots situated on eight organic farms and were composed of 16 low-input meadows, six low-input pastures, seven herbaceous strips adjacent to hedges, five sown flower strips and eleven organic cereal fields. All of them are financially subsidised by the Swiss agri-environmental scheme. Wild bees were sampled between the end of April and end of August 2014 by using trio-pan traps and complementary sweep netting on these five habitat types. On 45 plots we recorded 3973 bee specimens, belonging to 91 species, 16 of which are red listed, revealing a high bee species richness in the study area. Wild bee species richness and abundance were best explained by habitat type, number of flowering plants and site. A strong relationship of increasing number of flowering plants and bee species richness and abundance was found. Grassland habitats, especially low-input meadows, harboured the highest species richness and abundances. Organic cereal fields showed a potential to conserve bee species relevant to nature conservation (harbouring exclusively two red list species and four rare species). Ordination analysis of the bee communities showed a relative dissimilarity between the habitat types and indicates their complementary effects to benefit the diversity of wild bees. Our results demonstrate that a matrix of low-input habitats are needed to sustain rich assemblages of wild bees in agroecosystems.     

Species richness and composition patterns across trophic levels of true bugs (Heteroptera) in the agricultural landscape of the lower reach of the Tisza River Basin

River basins are among the most threatened ecosystems. The species diversity of several European river basins decreased seriously during the last decade due to loss of habitats and increasing land use pressure on the remaining habitats. We studied true bug assemblages in various land use types of grassland fragments and dikes as linear grassland habitats in the agricultural landscape of the lower reach of the Tisza River Basin. We tested the effects of the recorded variables of habitat quality, surrounding landscape and land use type on the abundance, species richness and composition of true bugs. Altogether, 5,389 adult Heteroptera individuals representing 149 species in 13 families were collected. The factors which influenced significantly the species richness of different trophic levels (i.e. herbivors, predators) and degrees of food specialization (i.e. generalist and specialist herbivors) were concordant. Contrary to this, the factors which influenced the abundance of the different feeding groups varied strongly. We emphasise the vegetation and land use types as primarily influential factors for insects. Excluding the grass-feeding species, the number of both generalist, specialist herbivorous and predaceous species were lower in agricultural swards, i.e. hay-meadows and pastures than in old field and dike habitats and their number increased with increasing vegetation diversity. Due to the high species richness and abundance observed in dike and old field habitats compared to agricultural swards, we emphasise their importance for conservation of insect diversity and we stress the negative effects of agricultural intensification on the remaining grasslands of the lower reach of the Tisza River Basin.     

Succession of bee communities on fallows

Wild bee communities were studied on one- to five-year-old set-aside fields with naturally developed vegetation (n = 20). and old orchard meadows (n = 4) to analyse effects of secondary succession on species diversity, resource use and associated life history traits. General theory predicts a steady increase of species richness with age of succession. In contrast, we found a first maximum in species richness of bees on two-year-old set-aside fields and a second on old meadows. Successional changes of bee communities were related to changes of vegetation. The transition from pioneer successional stages, dominated by annuals, to early successional stages, dominated by perennials, resulted in the highest species richness of flowering plants in the second year within the first five years of succession. Species richness of flowering plants was the best predictor variable for species richness of bees, whereas the cover of flowering plants correlated with the abundance of bees. Annual plants were visited more often and perennials less often than expected from their flower cover. Halictidae tended to prefer flowers of annuals, whereas Megachilidae. Apidae and Anthophoridae significantly preferred perennials. In departure from successional theory, body size, proportion of specialised bees and proportion of parasitic bees did not significantly increase with successional age, but number of generations and the proportion of soil-nesting bees decreased with successional age. Comparison of different management types showed that set-aside fields with naturally developed vegetation supported much more specialised and endangered bee species than set-aside fields sown with Phacelia tanacetifolia.     

Interaction diversity within quantified insect food webs in restored and adjacent intensively managed meadows

1. We studied the community and food-web structure of trap-nesting insects in restored meadows and at increasing distances within intensively managed grassland at 13 sites in Switzerland to test if declining species diversity correlates with declining interaction diversity and changes in food-web structure. 2. We analysed 49 quantitative food webs consisting of a total of 1382 trophic interactions involving 39 host/prey insect species and 14 parasitoid/predator insect species. Species richness and abundance of three functional groups, bees and wasps as the lower trophic level and natural enemies as the higher trophic level, were significantly higher in restored than in adjacent intensively managed meadows. Diversity and abundance of specific trophic interactions also declined from restored to intensively managed meadows. 3. The proportion of attacked brood cells and the mortality of bees and wasps due to natural enemies were significantly higher in restored than in intensively managed meadows. Bee abundance and the rate of attacked brood cells of bees declined with increasing distance from restored meadows. These findings indicate that interaction diversity declines more rapidly than species diversity in our study system. 4. Quantitative measures of food-web structure (linkage density, interaction diversity, interaction evenness and compartment diversity) were higher in restored than in intensively managed meadows. This was reflected in a higher mean number of host/prey species per consumer species (degree of generalism) in restored than in intensively managed meadows. 5. The higher insect species and interaction diversity was related to higher plant species richness in restored than in intensively managed meadows. In particular, bees and natural enemies reacted positively to increased plant diversity. 6. Our findings provide empirical evidence for the theoretical prediction that decreasing species richness at lower trophic levels should reduce species richness at higher trophic levels, and in addition lead to even stronger reductions in interaction diversity at these higher levels. Species at higher trophic levels may thus benefit relatively more than species at lower trophic levels from habitat restoration in the grassland ecosystems studied. We also demonstrate enhanced compartment diversity and lower interaction evenness in restored than in intensively managed meadows, both of which are theoretically positively associated with increased ecosystem stability in restored meadows.     

A landscape ecology approach identifies important drivers of urban biodiversity

Cities are growing rapidly worldwide, yet a mechanistic understanding of the impact of urbanization on biodiversity is lacking. We assessed the impact of urbanization on arthropod diversity (species richness and evenness) and abundance in a study of six cities and nearby intensively managed agricultural areas. Within the urban ecosystem, we disentangled the relative importance of two key landscape factors affecting biodiversity, namely the amount of vegetated area and patch isolation. To do so, we a priori selected sites that independently varied in the amount of vegetated area in the surrounding landscape at the 500‐m scale and patch isolation at the 100‐m scale, and we hold local patch characteristics constant. As indicator groups, we used bugs, beetles, leafhoppers, and spiders. Compared to intensively managed agricultural ecosystems, urban ecosystems supported a higher abundance of most indicator groups, a higher number of bug species, and a lower evenness of bug and beetle species. Within cities, a high amount of vegetated area increased species richness and abundance of most arthropod groups, whereas evenness showed no clear pattern. Patch isolation played only a limited role in urban ecosystems, which contrasts findings from agro‐ecological studies. Our results show that urban areas can harbor a similar arthropod diversity and abundance compared to intensively managed agricultural ecosystems. Further, negative consequences of urbanization on arthropod diversity can be mitigated by providing sufficient vegetated space in the urban area, while patch connectivity is less important in an urban context. This highlights the need for applying a landscape ecological approach to understand the mechanisms shaping urban biodiversity and underlines the potential of appropriate urban planning for mitigating biodiversity loss.     

Analysis of macrofungal communities reveals a complex reciprocal influence between Mediterranean montane calcareous grassland and surrounding forest habitats

Fungi are essential components of all terrestrial ecosystems. Despite the crucial ecological role of soil fungi in grasslands, knowledge about fungal community diversity and structure in Mediterranean meadow habitats is still fragmentary. We analyzed macrofungal communities in three geographically distinct Mediterranean montane calcareous grasslands and surrounding forests, by means of fruit body surveys. We investigated a number of biotic and abiotic factors influencing the studied fungal communities, including plant species composition. Out of 6365 fruit bodies, a total of 268 species belonging to 84 genera were found. In general, there was a significant correlation between plant species richness and fungal richness. Variation in vegetation and plant community structure accounted for approximately 20% of variance in fungal community structure. Tree and shrub vegetation played a dominant role in shaping the analyzed fungal communities, both in meadows and surrounding forests, with particular influence on ectomycorrhizal, litter, and lignicolous saprotrophic fungi. Fungal biodiversity in the studied meadows was increased by the presence of tree and shrub species from the adjacent forests, but was reduced by the increasing vegetation cover.     

Landscape- and time-dependent benefits of wildflower areas to ground-dwelling arthropods

Wildflower areas are a popular agri-environment scheme to counteract agro-biodiversity loss. Yet, their benefits are controversially discussed. Since inconsistent benefits may be owed to landscape context and temporal dynamics, we applied a multi-year study to unravel effects of permanent and transient habitats on ground-dwelling arthropods in wildflower areas and cereal fields.Across three consecutive years, we studied activity density, species richness and community composition of rove beetles, carabid beetles and spiders in ten pairs of wildflower areas and cereal fields along independent gradients of proportions of permanent semi-natural habitats or transient wildflower areas.Arthropod responses to the proportions of permanent semi-natural habitats often followed a hump-shaped pattern, whereas transient wildflower areas seemed to drive linear responses. An interactive effect on rove beetle richness in wildflower areas implies that benefits were highest either at intermediate proportions of permanent semi-natural habitats or at lower proportions, but with additional availability of transient wildflower areas or in landscapes with low proportions of permanent semi-natural habitats, but high proportions of wildflower areas. However, ground-dwelling arthropod activity density or species richness did not systematically increase over the three study years.Our results suggest that both permanent and transient habitats differ in how they affect biodiversity, possibly due to different temporal continuity and resource diversity. Benefits of permanent semi-natural habitats seemed highest at an equilibrium between an increasing resource-related species pool and an increasing diversity dilution, whereas benefits of transient wildflower areas seemed to increase with resource complementarity and connectivity at the landscape scale. Nevertheless, both habitats seem to complement each other and considered in concert, seem to be most effective in promoting benefits of wildflower areas to ground-dwelling arthropods at intermediate landscape complexity. The substantial variation in diversity patterns among years with weather extremes, suggests that optimizing benefits of wildflower areas requires further multi-year studies.     

Butterflies and bumblebees in greenways and sown wildflower strips in southern Sweden

Greenways have recently been established in some intensively farmed areas of South Sweden in order to enhance recreation opportunities and biodiversity, but the effects of these green structures on biodiversity have not yet been determined. In this study, greenways and experimental sown wildflower strips were investigated for butterfly and bumblebee diversity. In total, 1,769 butterflies of 18 species and 1,216 foraging bumblebees of eight species were recorded. Sown wildflower strips proved to support much higher abundances and species numbers of butterflies and bumblebees than greenways, with 86% of all butterflies and 83% of all bumblebees being observed in the sown flower strips. However, in both types of green structure mostly common species were found. Counts of flower visits showed that Knautia, Centaurea and Cirsium were the most commonly visited plant species. The greenways studied did not seem to fulfil their function of enhancing biodiversity—at least not for butterflies and bumblebees. However, these greenways could easily be improved for common bumblebee and butterfly species by sowing wildflower strips along their margins.