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Biodiversity is declining at unprecedented rates worldwide due largely to land use change and abnormal disturbance events. The high species diversity and endemicity found in California's coastal sage scrub (CSS) are especially at risk from urban development and ongoing disturbance. However, several CSS plant species have disturbance adaptations which may allow them to serve as vital resources for insect pollinators when native plant diversity is threatened. Common fiddleneck (Boraginaceae; Amsinckia menziesii var. intermedia) is one of the first annual forbs to germinate in CSS and as a result, it occurs in high density patches in early spring which temporarily creates a near monoculture. Although fiddleneck is a prominent CSS plant, particularly in areas that have experienced a disturbance event, its larger ecological role is not well explored. Therefore, we monitored ten sites across a disturbance gradient for two spring seasons to assess the composition of plant-pollinator networks in fiddleneck-dominated plots. We found fiddleneck supported a diverse pollinator community with 68% of recorded taxa visiting fiddleneck. The plants most frequently visited included two native annual forbs (common fiddleneck and Phacelia distans) and two invasive annual forbs (Erodium cicutarium and Brassica tournefortii). Increased mean precipitation resulted in increased plant abundance but decreased native pollinator diversity. Additionally, plant-pollinator networks changed over time; the number of links per species increased throughout the season but did not differ among disturbance types. Despite the numerical dominance of fiddleneck, CSS supported a diversity of pollinator taxa and exhibited complex plant-pollinator networks across the disturbance gradient. [ABSTRACT FROM AUTHOR]

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California's sage scrub habitats support a diversity of nectar and host plants for migrating and resident populations of painted lady butterflies (Vanessa cardui) throughout all seasons. North America experiences spring V. cardui migrations involving butterflies totaling in the millions in some years. These irruptive years are thought to be driven by winter weather patterns at breeding grounds near the US–Mexico border and due to their irregularity, it is difficult to study floral resource use along the migration route. Here we used the community science platform iNaturalist to quantify patterns in V. cardui nectar resource use in sage scrub over time and space during irruptive and nonirruptive years. We identified over 329 different nectaring plant species of varying functional types (72% native to California) visited by adult V. cardui, 195 of which had not been previously identified as known nectar plants for V. cardui. Vanessa cardui butterflies were observed in similar locations regardless of whether an irruptive migration occurred, indicating the presence of either sparse migrants or resident populations across California. Moreover, irruptive years were positively correlated with warmer and wetter local conditions at observation locations. Our results provide new insights into patterns of floral resource use by North American V. cardui by harnessing the power of community science data and while highlighting the factors associated with its North American migration. [ABSTRACT FROM AUTHOR]

Farmland birds can suppress insect pests, but may also consume beneficial insects, damage crops and potentially carry foodborne pathogens. As bird communities shift in response to farming practices, so too do the benefits (services) and costs (disservices) from birds. Understanding how and why ecosystem services and disservices covary can inform management interventions that enhance synergies, avoid trade‐offs and promote multifunctionality.We investigated how farmland diversification practices influence the services and disservices provided by wild birds on 21 California strawberry farms. Specifically, we coupled 285 bird surveys, metabarcoding and other molecular analyses of ~1,000 faecal samples representing 55 bird species (mostly passerines) to determine which individuals consumed pests, natural enemies, and crops and carried foodborne pathogens. Then, we explored how farming practices shape ecosystem service bundles, or suites of consistently co‐occurring services/disservices.Avian services and disservices were shaped by interactions between local farming practices and landscape context. We found that the amount of semi‐natural habitat surrounding each farm was the single most important driver of ecosystem services, with the best outcomes (highest multifunctionality) occurring on farms surrounded by semi‐natural habitat.Bundles were primarily influenced by landscape context. Increasing semi‐natural habitat around farms was associated with more multifunctional bird communities that maximized services and minimized disservices. However, not all trade‐offs were minimized in landscapes with more semi‐natural habitat, suggesting that specific farming contexts can exacerbate or mitigate trade‐offs as bird communities shift in response to diversification practices.Synthesis and applications. Though growers are often pressured to remove non‐crop habitat to reduce food‐safety risks, our work suggests that conserving habitat can support bird conservation, mitigate food‐safety risks and decrease crop damage from birds. More broadly, by considering the multiple roles that communities play in ecosystems, managers can simultaneously maximize services and minimize disservices to achieve multifunctionality. [ABSTRACT FROM AUTHOR]

In human-modified landscapes, understanding how habitat characteristics influence the diversity and composition of beneficial organisms is critical to conservation efforts and modeling ecosystem services. Assessing turnover, or the magnitude of change in species composition across sites or through time, is crucial to said efforts, yet is often overlooked. For pollinators such as wild bees, variables influencing temporal turnover, particularly across seasons within a year, remain poorly understood. To investigate how local and landscape characteristics correlate with bee diversity and turnover across seasons, we recorded wild bee and flowering ornamental plant assemblages at 13 plant nurseries in California between spring and autumn over 2 years. Nurseries cultivate a broad diversity of flowering plant species that differ widely across sites and seasons, providing an opportunity to test for correlations between turnover and diversity of plants and bees. As expected, we documented strong seasonal trends in wild bee diversity and composition. We found that local habitat factors, such as increased cultivation of native plants, were positively associated with bee diversity in sweep netting collections, whereas we detected moderate influences of landscape level factors such as proportion of surrounding natural area in passive trap collections. We also detected a moderate positive correlation between the magnitude of turnover in plant species and that of bee species (as number of taxa gained) across consecutive seasons. Our results have implications for the conservation of wild bees in ornamental plant landscapes, and highlight the utility of plant nurseries for investigating hypotheses related to diversity and turnover in plant–pollinator systems. [ABSTRACT FROM AUTHOR]

1. An ongoing challenge in ecology is predicting how characteristics of communities correspond to habitat features. Examining variation in functional traits across species may reveal patterns not discernible from measures of mere abundance or richness. For beneficial insects like wild bees, functional trait‐based approaches are often used to characterise communities in different agricultural habitats. 2. However, no such approach has yet been applied in horticultural plant nurseries, which represent intensively managed artificial flowering plant assemblages. Certain nurseries mostly cultivate regionally native flowering plants, allowing one to test how differences between local plant assemblages may correlate with bee functional traits. 3. We surveyed bee assemblages at native and conventional plant nurseries in southern California from spring through autumn over 2 years, while also documenting the native status of blooming plants in sampling plots. Bees were classified into different functional categories based on their diet breadth, nesting location, and social organisation. 4. At native plant nurseries, we netted proportionally more specialist bee species and fewer generalist species than at conventional nurseries. Nesting location and social organisation of bee samples did not differ between nursery types. Meanwhile, landscape‐level features were not associated with any observed functional trait metrics of bee collections. Furthermore, network‐level specialisation of bee‐plant interactions was higher at conventional nurseries. 5. Our results suggest that a horticultural cultivation practice is quantifiably correlated with the functional distribution of resident bee assemblages. These results are important and encouraging to pollinator conservation efforts in nursery systems and other human‐modified landscapes dominated by ornamental plants. [ABSTRACT FROM AUTHOR]

Mark-recapture experiments reveal foraging behavior and plant fidelity of native bees in plant nurseries Keywords: agroecosystems; California; foraging fidelity; Halictus; native plants; ornamental plants EN agroecosystems California foraging fidelity Halictus native plants ornamental plants 1 4 4 06/04/20 20200601 NES 200601 Understanding the spatial and temporal foraging patterns of pollinators is essential to conserving these organisms in human-modified landscapes, such as agroecosystems (Cranmer et al. [3]). These bees not only foraged in the same general location the next day, but of the 106 recaptured bees, 102 (96.2%) foraged on the same plant species as the previous day despite the broad diversity of plants flowering in nurseries. Although more bees were recaptured on native plants overall, some bees still displayed relatively high rates of fidelity to nonnative plants, though we found no preference for or against any nonnative plant species. [Extracted from the article]

Agricultural intensification and expansion have degraded biodiversity in agroecosystems, jeopardizing the ecosystem services provided by wildlife. Birds can act as particularly important purveyors of ecosystem services to farmers by consuming arthropod pests. Some bird species, however, may sometimes act as pests themselves by consuming crops. Further, on-farm management practices (e.g., crop diversity, vegetative structure) and the complexity of the surrounding landscape can shift the balance of bird-mediated ecosystem services and disservices through changes in bird community composition. Here, we explored how organic strawberry farms in California could be managed to bolster bird biodiversity and shift community composition from strawberry-consuming to pest-eating species. Using multi-species N-mixture models we found that semi-natural habitat at the landscape (1000 m) and farm (50 m) scales were positively associated with mean abundance of all birds, with varying effects on different species. In particular, we found that the mean local abundance of species that consume Lygus spp. (a major pest), but not strawberry-consuming species, increased with semi-natural habitat at the farm scale. Nest density in developed areas within farms also increased with greater semi-natural habitat in the landscape, while nest density in semi-natural habitat within farms decreased with increasing semi-natural habitat in the landscape. Further, nest density of Lygus spp. eating birds increased with increasing local semi-natural habitat. These results suggest that increasing semi-natural habitat at the landscape and local scales can bolster bird abundance across farms, while pest control can be promoted locally by conserving or restoring semi-natural vegetation at the farm scale. • We paired bird surveys with molecular diet data to identify key ecosystem service/disservice providers of strawberry farms. • N-mixture models show that community-wide bird abundance responds to seminatural habitat at local and landscape scales. • Birds that consume Lygus increase with local seminatural habitat, suggesting local seminatural habitat promotes biocontrol. [ABSTRACT FROM AUTHOR]