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.     

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.     

Novel management to enhance spider biodiversity in existing grass buffer strips

• 1 Grass buffer strips have been widely sown to mitigate against intensive agricultural management practices that have negatively impacted on invertebrate and plant biodiversity in arable farming systems. Typically, such strips are floristically species poor and are dominated by grasses. In the present study, we developed management practices to enhance the floristic and structural diversity of these existing strips for the benefit of spiders, a key provider of natural pest control in crops.
• 2 Across three UK arable farms, we investigated the benefits of: (i) scarification to create germination niches into which wildflower seeds were sown and (ii) the effect of graminicide applications to suppress grass dominance. Spiders were sampled twice per year (July and September) during 2008 and 2009.
• 3 The combination of scarification with wildflower seeds, as well as graminicide, resulted in the greatest wildflower cover and lowest grass cover, with a general trend of increased abundance of adult and juvenile spiders. The abundance of Pachygnatha degeeri, Bathyphantes gracilis and juvenile wolf spiders of the genus Pardosa was positively correlated with wildflower cover, probably reflecting increased prey availability. Sward structure was negatively correlated with Erigone atra, Oedothorax fuscus and juvenile Pardosa abundance.
• 4 Management that utilizes existing commonly adopted agri‐environment options, such as grass buffer strips, represents a potentially important conservation tool for increasing the quantity and quality of invertebrate habitats. This can maximize opportunities for the provision of multiple ecosystem services, including pest regulation by predators such as spiders. These management practices have the potential to be incorporated into existing U.K. and European agri‐environment schemes.

     

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.     

Seed mixture strongly affects species-richness and quality of perennial flower strips on fertile soil

Within the frame of the EU Common Agricultural Policy, most countries subsidise the establishment and maintenance of perennial flower strips on arable land within Agri-Environmental Schemes to provide foraging habitats and refuges for wildlife.In a replicated field experiment, we studied the effects of different types of seed mixtures on the establishment and maintenance of perennial flower strips on fertile arable land in the federal state of Saxony-Anhalt, Germany over seven years. The seed mixtures were commonly applied within recent Common Agricultural Policy funding periods: (1) a low-diversity cultivar standard seed mixture (CULTIVAR), (2) a high-diversity cultivar and native plant mixture (MIX), and (3) a high-diversity native plant mixture (WILDFLOWER). All plots were mulched every year in March and at the beginning of August.The low success of CULTIVAR triggered the massive encroachment of spontaneously established perennial grasses. In MIX, too, cultivars have disappeared after the first year. Both wildflower variants were successful in maintaining a high cover of sown perennial native forbs and a high ratio of established sown species, even after seven years. WILDFLOWER always tended to show better values than MIX. Furthermore, spontaneously establishing species began to spread their cover in MIX in the fifth year, with a very strongly increasing tendency, whereas in WILDFLOWER cover of spontaneously immigrating species stayed satisfyingly low.Using native wildflowers to establish perennial wildflower strips was very effective in maintaining high species diversity within the Agri-Environmental Schemes funding period of five years and beyond. WILDFLOWER was especially successful. On the other hand, CULTIVAR failed completely. On fertile soils in regions with rather low yearly precipitation, mulching twice a year supported the maintenance of perennial wildflower strips.     

Establishment and management of wildflower areas for insect pollinators in commercial orchards

Sown wildflower areas are increasingly recommended as an agri-environmental intervention measure, but evidence for their success is limited to particular insect groups or hampered by the challenges of establishing seed mixes and maintaining flower abundance over time. We conducted a replicated experiment to establish wildflower areas to support insect pollinators in apple orchards. Over three years, and across 23 commercial UK orchards with and without sown wildflowers, we conducted 828 transect surveys across various non-crop habitats. We found that the abundance of flower-visiting solitary bees, bumblebees, honeybees, and beetles was increased in sown wildflower areas, compared with existing non-crop habitats in control orchards, from the second year following floral establishment. Abundance of hoverflies and other non-syrphid flies was increased in wildflower areas from the first year. Beyond the effect of wildflower areas, solitary bee abundance was also positively related to levels of floral cover in other local habitats within orchards, but neither local nor wider landscape-scale context affected abundance of other studied insect taxa within study orchards. There was a change in plant community composition on the sown wildflower areas between years, and in patterns of flowering within and between years, showing a succession from unsown weedy species towards a dominance of sown species over time. We discuss how the successful establishment of sown wildflower areas and delivery of benefits for different insect taxa relies on appropriate and reactive management practices as a key component of any such agri-environment scheme.     

Larger patches of diverse floral resources increase insect pollinator density,diversity, and their pollination of native wildflowers

Native wildflower plantings can be used to provide nutritional resources to support pollinating insects, yet the effects of planting size and bloom richness on the density, diversity, and function of these insects are not well understood. We established stands of twelve native flowering perennial plant species in replicated plots ranging in size from 1 to 100 m². These plots were sampled for insect pollinators, bloom richness, and seed production by three wildflower species. Honeybees, wild bees, and hoverflies all responded positively to increasing flower richness, whereas particular insect pollinator groups responded differently to the size of the flowering plant area. The density of honeybees and hoverflies was not affected by increasing flowering patch size, whereas in general, wild bees were observed at higher density and diversity in the 30 and 100 m² patches. Increasing wildflower patch size, and thus wild bee density, resulted in greater seed set in the sampled wildflowers. These results indicate that wild bees are sensitive to the area and richness of floral resources in patches, even at relatively small scales. Therefore, larger wildflower plantings with more diverse flower species mixes are more suitable for the conservation of wild pollinators and reproduction of sown species.     

Evaluating butterflies as surrogates for birds and plants in semi-natural grassland buffers

Semi-natural grasslands can support diverse faunal and floral communities, including grassland birds, beneficial insects, and native wildflowers. Monitoring biodiversity of this type of ecosystem is important to assess abundance and richness of grassland-associated species, evaluate success of establishing grasslands, and to assess overall ecosystem health. We tested butterflies as surrogates for birds and plants to assess establishment success of semi-natural grassland buffers in north-central Mississippi using Spearman rank correlation (Spearman’s ρ). Disturbance and grassland butterfly guilds were generally not suitable surrogates for grassland bird metrics, non-grassland bird metrics, or nest density metrics. Butterflies did have consistent positive correlations with plant species richness and forb metrics, as well as consistent negative correlations with grass metrics, but these correlations were generally smaller than what is considered suitable to serve as surrogates. In general, butterflies were not suitable surrogates for birds or plants in semi-natural grassland buffers.     

Wildflower-pollinator interactions: Which phytochemicals are involved?

The intensification of agricultural practices contributes to the decline of many taxa, such as insects and weeds. Wildflower species have an important environmental impact on rural biodiversity since plant-pollinator networks play a key role in both landscape aesthetics and environmental functionality. Due to their scarcity and/or disappearance in conventional agroecosystems, wildflowers are now being used in strips to restore the agro-environment.In this study, fifteen wildflower species were sown in order to verify their ecological performance in terms of a plant-pollinator interaction while in laboratory the several chemicals emitted by the flowers were identified. Flowering periods were concentrated in the spring, although flowering periods extended to the hot and dry summer months in some species. An extreme variability was found in terms of quantitative and qualitative pollinator-attractiveness (i.e., bees, bumblebees, hoverfly, bee flies and butterflies). Most wildflower species emit a volatiles belonging above all to one of the several chemical classes. A hierarchical cluster analysis of the different volatile emissions did not fully correlate with the botanical taxa of the respectives wildflowers. Often, single chemical compounds prevailed, such as β-ocimene and limonene among monoterpenes hydrocarbons, santolina alcohol in the case of oxygenated monoterpenes, or (Z)- or (E)-3-hexenol acetate for non-terpenes derivatives. It is believed that these chemical compounds can play an ecological role in plant-pollinator food webs. The hypothesis that the chemistry of the volatiles implies a specialized plant-pollinator co-evolution was confirmed by a significant regression (p < 0.05), which showed an inverse relationship between chemical diversity (H’) and pollinator dominance (D) indexes. The chemical specificity indicates the specificity of pollinators and vice versa.     

Habitat quality and surrounding landscape structures influence wild bee occurrence in perennial wildflower strips

Perennial wildflower strips (WFS) are known to have positive effects on wild bees in intensively used agricultural landscapes. Little knowledge exists, however, about the drivers of wild bee occurrence and if Red List species also profit from this agri-environmental scheme (AES). Therefore, we studied wild bees on transects along 20 four- to five-year-old WFS and in 10 cereal fields without AES (CONTROL sites) in differently structured landscapes across Saxony-Anhalt (Germany). In addition to local site parameters, we measured parameters of landscape structure in a 1 km radius of the WFS and CONTROL sites. The overall species richness of wild bees (125 species in total, 23 on average), including numerous specialist and Red List species, indicates a high attractiveness of perennial WFS sown with 30 native forbs. In CONTROL fields, 11 bee species (on average only one) were found.The species richness and abundance of wild bees were positively affected by local site conditions of the WFS and CONTROL sites, such as the overall number of sown and spontaneous forbs, the amount of flower rewards of sown forbs available to pollinators (Pollinator Feeding Index), and negatively by the cover of grasses. Therefore, seed mixtures of future AES should comprise a high diversity of wildflower species relevant as pollen sources for wild bees. The share of Red List wild bee species was strongly influenced by the landscape context and increased e.g. with Shannon landscape diversity and the availability of non-forest woody habitats and water bodies in the 1 km surroundings. These results suggest that besides the establishment of high-diversity WFS, semi-natural habitat structures have to be promoted to preserve rare wild bees especially in structurally simple agricultural landscapes.     

Proximity to wildflower strips did not boost crop pollination on small,diversified farms harboring diverse wild bees

The yield of many agricultural crops depends on pollination services provided by wild and managed bees, many of which are experiencing declines due to factors such as reductions in floral resources. Thus, improving pollinator habitat on farmlands using management strategies like planting wildflower strips is vital for wild bee conservation and sustainable crop pollination. Yet, few studies have examined whether and at what spatial scales wildflower strips enhance crop pollination and yields, and most research has been conducted in large-scale commercial agriculture. Therefore, we investigated the effects of wildflower strips on crop pollination on small, diversified farms (i.e., those growing a variety of crop species) where wild bee diversity and abundance is predicted to be comparatively high. Over three years, on four diversified farms in Montana USA, we tested the hypothesis that distance (20, 60, and 180 m) of crops from native perennial wildflower strips planted alongside crop fields affected wild bee visitation, pollination, and yields of squash and sunflower crop plants. We found that distance to wildflower strips did not affect bee visitation or pollination in crops. Squash yield was pollen-limited in the growing season prior to wildflower strip establishment, and in one of the two years after wildflower strip establishment, but proximity to wildflower strips did not influence the magnitude of pollen limitation. Sunflower seed production was not pollen-limited in any year. Our findings demonstrate that even on diverse farms with wildflower strips and a demonstrated high diversity of bees, some crops do not necessarily receive maximum pollination, regardless of distance from the wildflower strips. However, the value of wildflower strips for supporting wild bee diversity, and other ecological or economic benefits, needs consideration for a full understanding of this pollinator habitat management strategy.     

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.     

Redundancy in wildflower strip species helps support spatiotemporal variation in wild bee communities on diversified farms

Wildflower strips are a management practice increasingly used to provide floral resources to wild bees in agroecosystems. Yet, despite known spatiotemporal variation in wild bee communities, the degree to which different wildflower strip species consistently support wild bee communities is poorly understood. Additionally, whether such consistency is related to the functional roles wildflower species play (e.g., in supporting diverse, rare, or unique suites of bee species) has not been considered. Over three years and on four diversified farms, we evaluated spatiotemporal variation in wild bee communities and bee-flower interactions in wildflower strips to better understand the roles of flower strip species in supporting bees. We documented spatiotemporal variation in the abundance, richness, and composition of local wild bee communities. Certain wildflower species consistently supported the highest richness of wild bees across years. These wildflower species were regularly core members of the bee-flower interaction network, visited by both generalist and specialist bees. By contrast, wildflower species supporting the most unique suites of bees were variable in this role among farms. In order to select plant species for wildflower strips that consistently support a high diversity of wild bee communities within farm landscapes, it is useful to consider several different functional roles that plants may play. Whereas a handful of wildflower species may be visited by the majority of local wild bee species, achieving support for the remaining, and perhaps rarer, bee species will require planting additional flower species, which may appear redundant until the spatiotemporal variation in wild bee communities is more thoroughly considered. This functional approach to selecting wildflower species for bee conservation efforts is important for making practical recommendations to land managers and for guiding best management practices in different regions and with diverse management goals.     

Environmental determinants of geographic butterfly richness pattern in eastern China

A long-standing task for ecologists and biogeographers is to reveal the underlying mechanisms accounting for the geographic pattern of species diversity. The number of hypotheses to explain geographic variation in species diversity has increased dramatically during the past half century. The oldest and the most popular one is environmental determination. However, seasonality, the intra-annual variability in climate variables has been rarely related to species richness. In this study, we assessed the relative importance of three environmental hypotheses: energy, seasonality and heterogeneity in explaining species richness pattern of butterflies in Eastern China. In addition, we also examined how environmental variables affect the relationship between species richness of butterflies and seed plants at geographic scale. All the environmental factors significantly affected butterfly richness, except sampling area and coefficient of variation of mean monthly precipitation. Energy and seasonality hypotheses explained comparable variation in butterfly richness (42.3 vs. 39.3 %), higher than that of heterogeneity hypothesis (25.9 %). Variation partitioning indicated that the independent effect of seasonality was much lower (0.0 %) than that of energy (5.5 %) and heterogeneity (6.3 %). However, seasonality performed better in explaining butterfly richness in topographically complex areas, reducing spatial autocorrelation in butterfly richness, and more strongly affect the association between butterflies and seed plants. The positive relationship between seed plant richness and butterfly richness was most likely the result of environmental variables (especially seasonality) influencing them in parallel. Insufficient sampling may partly explain the low explanatory power of environmental model (52.1 %) for geographic butterfly richness pattern. Our results have important implications for predicting the response of butterfly diversity to climate change.     

Assessing a farmland set-aside conservation program for an endangered butterfly: USDA State Acres for Wildlife Enhancement (SAFE) for the Karner blue butterfly

Private lands provide critical habitat for threatened and endangered species, but only recently have farm-based conservation programs focused on at-risk, invertebrate species. The USDA Conservation Reserve Program State Acres for Wildlife Enhancement (CRP-SAFE) is one of the first federal programs to do so with a Wisconsin-based initiative for the US federally endangered Karner blue butterfly (KBB). This study is the first to evaluate how well the KBB-SAFE provides suitable habitat for the Karner and other butterflies. It also provides a critical foundation for better understanding the potential of new USDA programs that create pollinator habitat including for declining species such as the Monarch butterfly. Here we compare data (2009–2014) on assemblages of grassland communities, blooming floral resource availability, and abundance and richness of butterflies, between KBB-SAFE and native prairie sites. We found that KBB-SAFE and native sites had distinctly different forb species assemblages, with SAFE sites having fewer native blooming species available during the first flight of the KBB yet similar availability during second flight. Butterfly abundance was ultimately greater on native sites compared to SAFE sites, but richness was comparable between sites. We conclude that KBB-SAFE can provide habitat for many grassland species, and serve as surrogate KBB habitat. We provide straightforward management recommendations designed to better meet the needs of the Karner blue and other sensitive butterfly species and we provide further evidence that increased abundance and richness of native forbs and grasses on land formerly used for agriculture can provide habitat for butterflies adapted to early successional habitats.     

The promotion of grassland forb abundance: A chemical or biological solution?

Techniques that increase the biodiversity value of species-poor grassland are required if conservation targets aimed at reversing the decline in species-rich grassland are to be met. This study investigated the diversification of swards dominated by Lolium perenne by testing the efficacies of two treatments applied to reduce competitive exclusion of species introduced as seed. The ‘biological’ treatment was the addition of the hemiparasitic plant species Rhinanthus minor, whilst the ‘chemical’ approach was the application of a selective graminicide, fluazifop-P-butyl (Fusilade 250EW). Changes in plant community composition were monitored for a period of 2 years. Values of plant species richness increased significantly between years regardless of treatment, but to a greater extent in plots sown with R. minor. The number of established sown species and their cover values were also significantly greater in association with R. minor. Fluazifop-P-butyl had no significant effect on species richness and tended to promote unsown species rather than those introduced as seed. Overall, the R. minor treatment was associated with the greatest impact on sward composition, facilitating establishment and development of the introduced species and promoting forb abundance.     

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.     

Impact of urbanization and gardening practices on common butterfly communities in France

We investigated the interacting impacts of urban landscape and gardening practices on the species richness and total abundance of communities of common butterfly communities across France, using data from a nationwide monitoring scheme. We show that urbanization has a strong negative impact on butterfly richness and abundance but that at a local scale, such impact could be mitigated by gardening practices favoring nectar offer. We found few interactions among these landscape and local scale effects, indicating that butterfly‐friendly gardening practices are efficient whatever the level of surrounding urbanization. We further highlight that species being the most negatively affected by urbanization are the most sensitive to gardening practices: Garden management can thus partly counterbalance the deleterious effect of urbanization for butterfly communities. This holds a strong message for park managers and private gardeners, as gardens may act as potential refuge for butterflies when the overall landscape is largely unsuitable.     

Vegetation development and floristical diversity of newly created sown and unsown field margin strips on ex arable land during the first 3 successional years

Early succesion of newly created sown/unsown margin strips on ex arableland, managed by two cuttings per year with/without removal of cuttings was characterised by the replacement of annuals in favour of perennials, a steadily increase in the importance of monocots and a decrease in non N-fixing dicots. Mowing with removal of cuttings delayed this succession pattern. Sorenson's qualitative similarity index (based solely on species occurrence) revealed that species composition of the sown communities (in terms of species occurrence) became increasingly similar to the unsown plots. Furthermore convergence in vegetation composition between sown and unsown plots occurred also in terms of species importance as assessed by Sorenson's quantitative index (based on the combination of species occurrence and importance). Similarity in species importance (but not of species occurrence) was significantly enhanced by cutting with removal of cuttings. During the first 3 successional years, species diversity of sown and unsown communities converged in time, irrespective of mowing regime or location. The decrease in species diversity, number of sown wildflower species and wildflower density of sown communities was more pronounced under a mowing regime without removal of cuttings. The annual addition of mown roadside herbage significantly enhanced species richness but not the importance of dicots.     

Effects of managing semi-natural grassland buffers on butterflies

Butterflies are important components of biodiversity in grassland ecosystems and provide ecosystem services such as pollination. Although agricultural intensification has led to a scarcity of native grassland habitats within most agricultural landscapes of North America, fragmented remnants and semi-natural habitats may support diverse communities, including butterflies, as long as vital resources such as host plants are available. The United States Department of Agriculture’s (USDA) Conservation Reserve Program practice CP33 Habitat Buffers for Upland Birds (USDA 2004) provides semi-natural grassland habitat in agricultural landscapes, but a knowledge gap exists about impacts of prescribed disturbance (e.g. burning or disking) on butterflies. We monitored butterfly habitat and butterfly communities on experimentally manipulated CP33 grassland buffers in Clay County, Mississippi from 2007 to 2009. Disturbance guild butterfly species richness did not differ among treatments. However, disturbance guild abundance was positively affected by disking in both the first and second growing seasons following disking, and the magnitude of this response varied between years. Effects of burning on disturbance guild abundance did not differ from the control treatment. There were no treatment differences for grassland guild butterfly abundance and species richness suggesting that periodic disturbance does not unduly impact grassland-associated butterflies in the southeastern US. Our results support current USDA practice standards that require periodic disturbance during the 10-year contract, but restrict the disturbance to 1/3 or 1/4 of grassland buffer area in a given year.