Pollinator Community Assembly Tracks Changes in Floral Resources as Restored Hedgerows Mature in Agricultural Landscapes

AbstractIn intensive agricultural landscapes semi-natural habitats for pollinators are often limited, although willingness to establish pollinator habitat is increasing among farmers. A common pollinator enhancement measure is to provide flower strips, but existent or improved hedgerows might be more effective. In this study, we compare the effectiveness of three pollinator enhancement measures at edges of conventional apple orchards: (i) perennial flower strips, (ii) existent hedgerows, and (iii) existent hedgerows complemented with a sown herb layer. We used orchard edges without any enhancement as control. The study took place over three consecutive years in Southern Germany. Wild bee abundance and species richness were highest in flower strips followed by improved hedges. Hoverflies were also most abundant in flower strips, but not more species rich than at control sites. Wild bee but not hoverfly community composition differed between control and enhancement sites. The overall pollinator community included only few threatened or specialized species. Flower abundance was the main driver for wild bee diversity, whereas hoverflies were largely unaffected by floral resources. Pollinator enhancement had neither an effect on the abundance or species richness within the orchards nor on apple flower visitation. Perennial flower strips seem most effective to enhance wild bees in intensive agricultural landscapes. Additionally, flower-rich hedgerows should be promoted to complement flower strips by extending the flowering period and to increase connectivity of pollinator habitat in agricultural landscapes.

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Dryland organic farming increases floral resources and bee colony success in highly simplified agricultural landscapes

Agriculture Ecosystems & Environment ◽

10.1016/j.agee.2018.10.010 ◽

2019 ◽

Vol 270-271 ◽

pp. 9-18 ◽

Cited By ~ 8

Author(s):

Subodh Adhikari ◽

Laura A. Burkle ◽

Kevin M. O’Neill ◽

David K. Weaver ◽

Fabian D. Menalled

Keyword(s):

Organic Farming ◽

Agricultural Landscapes ◽

Floral Resources ◽

Bee Colony

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Biotic and abiotic drivers of plant–pollinator community assembly across wildfire gradients

Journal of Ecology ◽

10.1111/1365-2745.13530 ◽

2020 ◽

Author(s):

Joseph A. LaManna ◽

Laura A. Burkle ◽

R. Travis Belote ◽

Jonathan A. Myers

Keyword(s):

Community Assembly ◽

Pollinator Community ◽

Plant Pollinator

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Modeling the Supporting Ecosystem Services of Depressional Wetlands in Agricultural Landscapes

Wetlands ◽

10.1007/s13157-020-01297-2 ◽

2020 ◽

Vol 40 (5) ◽

pp. 1061-1069

Author(s):

David M. Mushet ◽

Cali L. Roth

Keyword(s):

Ecosystem Services ◽

Crop Production ◽

System Modeling ◽

Integrated Approach ◽

Agricultural Landscapes ◽

Floral Resources ◽

Depressional Wetlands ◽

Native Plant ◽

Des Moines Lobe ◽

Des Moines

Abstract We explored how a geographic information system modeling approach could be used to quantify supporting ecosystem services related to the type, abundance, and distribution of landscape components. Specifically, we use the Integrated Valuation of Ecosystem Services and Tradeoffs model to quantify habitats that support amphibians and birds, floral resources that support pollinators, native-plant communities that support regional biodiversity, and above- and below-ground carbon stores in the Des Moines Lobe ecoregion of the U.S. We quantified services under two scenarios, one that represented the 2012 Des Moines Lobe landscape, and one that simulated the conversion to crop production of wetlands and surrounding uplands conserved under the USDA Agricultural Conservation Easement Program (ACEP). While ACEP easements only covered 0.35% of the ecoregion, preserved wetlands and grasslands provided for 19,020 ha of amphibian habitat, 21,462 ha of grassland-bird habitat, 18,798 ha of high-quality native wetland plants, and 27,882 ha of floral resources for pollinators. Additionally, ACEP protected lands stored 257,722 t of carbon that, if released, would result in costs in excess of 45-million USD. An integrated approach using results from a GIS-based model in combination with process-based model quantifications will facilitate more informed decisions related to ecosystem service tradeoffs.

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Taxon-specific temporal shifts in pollinating insects in mass-flowering crops and field margins in Ireland

Journal of Pollination Ecology ◽

10.26786/1920-7603(2021)628 ◽

2021 ◽

Vol 28 ◽

pp. 90-107

Author(s):

Irene Bottero ◽

Simon Hodge ◽

Jane Stout

Keyword(s):

Agricultural Landscapes ◽

Floral Resources ◽

Field Margins ◽

Flowering Period ◽

Field Margin ◽

Mass Flowering ◽

Insect Abundance ◽

Insect Pollinators ◽

Pollinating Insects ◽

Hover Flies

In intensively cropped agricultural landscapes, the vegetation in edges and hedges (henceforth “field margins”) represents an important semi-natural habitat providing fundamental resources for insect pollinators. We surveyed the pollinating insects associated with two mass-flowering crops, apple and oilseed rape, and compared the insect fauna of the main crop with that in the field margins in the grass-dominated agricultural landscapes of Ireland. Different insect groups responded differently to the presence of the flowering crop, with honey and bumble bees more abundant in crops than margins during crop flowering, but more hover flies and butterflies in margins throughout. The composition of the insect assemblage also shifted over time due to taxon-specific changes in abundance. For example, solitary bees were most abundant early in the season, whereas hover flies peaked, and butterflies declined, in mid-summer. The temporal shift in insect community structure was associated with parallel changes in the field margin flora, and, although we found no relationship between insect abundance and abundance of field margin flowers, Bombus abundance and total insect abundance were positively correlated with floral diversity. After the crop flowering period, floral abundance and diversity was maintained via margin plants, but by late summer, floral resources declined. Our results confirm the importance of field margins for insect pollinators of entomophilous crops set within grass-dominated landscapes, even during the crop flowering period, and provide additional support for agri-environment schemes that protect and/or improve field margin biodiversity. The results also demonstrate that although shifts in insect and plant communities may be linked phenologically there may not always be simple relationships between insect and floral abundance and richness.

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Modelling the effects of the repellent scent marks of pollinators on their foraging efficiency and the plant-pollinator community

PLoS ONE ◽

10.1371/journal.pone.0256929 ◽

2021 ◽

Vol 16 (9) ◽

pp. e0256929

Author(s):

Elise Verrier ◽

Emmanuelle Baudry ◽

Carmen Bessa-Gomes

Keyword(s):

Social Information ◽

Floral Resources ◽

Foraging Efficiency ◽

Scent Mark ◽

Scent Marks ◽

Agent Based ◽

Individual Fitness ◽

Pollinator Community ◽

Plant Pollinator ◽

Source Of Information

Pollinator insects forage in complex and unpredictable resource landscapes, often using social information from congeneric individuals to acquire knowledge about their environment. It has long been recognized that this process allows them to exploit floral resources more efficiently and thus increase individual fitness. However, by creating correlations between the behaviors of pollinators within a population, this could also indirectly influence the entire plant-pollinator community. One type of social information used by pollinators is the scent mark left on the corolla of flowers by previous visitors, which can be used as a cue to avoid recently depleted resources. We developed a spatially explicit agent-based model to examine the effects, at both individual and community levels, of pollinators using these scent marks. The model simulates a population of pollinators foraging on flowers in a continuous 2D space in which we can vary the density of pollinators. We showed that the use of scent marks as a source of information significantly increased the foraging efficiency of pollinators except when competition between pollinators was very low. At the community level, this also resulted in a marked homogenization between floral resources within the landscape: in the absence of scent marks, the coefficient of variation of the remaining nectar quantity per flower strongly increased with greater pollinator competition, but it remained low at all levels of competition when scent marks were used by the pollinators. Finally, the use of scent marks markedly decreased the number of pollinator flower visits, especially at high levels of pollinator competition, which can potentially reduce the pollination service.

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Evaluating Native Bee Communities and Nutrition in Managed Grasslands

Environmental Entomology ◽

10.1093/ee/nvaa009 ◽

2020 ◽

Vol 49 (3) ◽

pp. 717-725

Author(s):

D S Stein ◽

D M Debinski ◽

J M Pleasants ◽

A L Toth

Keyword(s):

Community Composition ◽

Tallgrass Prairie ◽

Native Species ◽

Management Strategies ◽

Health Indicators ◽

Flowering Plant ◽

Floral Resources ◽

Pollinator Community ◽

Bee Communities ◽

Bee Abundance

Abstract Native pollinators are important for providing vital services in agroecosystems; however, their numbers are declining globally. Bees are the most efficient and diverse members of the pollinator community; therefore, it is imperative that management strategies be implemented that positively affect bee community composition and health. Here, we test responses of the bee and flowering plant communities to land management treatments in the context of grasslands in the upper Midwestern United States, a critical area with respect to bee declines. Twelve sites were selected to examine floral resources and wild bee communities based on three different types of grasslands: tallgrass prairie remnants, ungrazed restorations, and grazed restorations. Total bee abundance was significantly higher in ungrazed restorations than remnants, but there were no significant differences among grasslands in community composition or Shannon diversity. Across the three grassland types we also examined mass and lipid stores as nutritional health indicators in three sweat bees (Halictidae), Augochlora pura, Agapostemon virescens, and Halictus ligatus. Although there were no differences in lipid content, total average bee mass was significantly higher in Ag. virescens collected from ungrazed restorations as compared to remnants. Floral abundance of native and non-native species combined was significantly higher in grazed restorations compared to remnants and ungrazed restorations. However, ungrazed restorations had higher abundance and richness of native flowering ramets. These data suggest that bee abundance and nutrition are driven by high abundance of native flowering plant species, rather than total flowering plants.

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Review for "Biotic and abiotic drivers of plant–pollinator community assembly across wildfire gradients"

10.1111/1365-2745.13530/v1/review1 ◽

2020 ◽

Keyword(s):

Community Assembly ◽

Pollinator Community ◽

Plant Pollinator

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Flower Strips in Wheat Intercropping System: Effect on Pollinator Abundance and Diversity in Belgium

Insects ◽

10.3390/insects9030114 ◽

2018 ◽

Vol 9 (3) ◽

pp. 114 ◽

Cited By ~ 4

Author(s):

Clara Amy ◽

Grégoire Noël ◽

Séverin Hatt ◽

Roel Uyttenbroeck ◽

Frank Van de Meutter ◽

...

Keyword(s):

Insect Pests ◽

Triticum Aestivum L ◽

Agricultural Landscapes ◽

Agricultural Systems ◽

System Effect ◽

Pollinator Abundance ◽

Pollinator Species ◽

Pollinator Community ◽

Abundance And Diversity ◽

Agricultural Areas

The decline of pollinators in agricultural areas has been observed for some decades, this being partly due to landscape simplification in intensive agrosystems. Diversifying agricultural landscapes by sowing flower strips within fields could reduce these adverse effects on biodiversity. In this context, the study presented here aimed at assessing and comparing the abundance and diversity of bees (Hymenoptera: Anthophila) and hoverflies (Diptera: Syrphidae) found and visiting flowers in three types of flower strips in Belgium: (i) a mixture of 11 wild flowers, (ii) a monofloral strip of Dimorphoteca pluvialis (Asteraceae) and (iii) a monofloral strip of Camelina sativa (Brassicaceae), where the last two are considered to be intercrops since they are valuable on the market, all sown within a field of winter wheat (Triticum aestivum L.). Pollinators were captured with pan traps and by netting in standardised transects from May to July 2017. One-thousand one-hundred and eighty-four individuals belonging to 43 bee species and 18 hoverfly species were collected. Significant differences in hoverfly diversity were found between the different flower strips. The multifloral treatment supported a greater diversity of syrphid species. Various pollinator species visited the different flowers composing the mixture and also D. pluvialis. The pollinator community proved to be predominantly generalist, with the exception of an oligolectic species in Belgium, Andrena nitidiuscula. Moreover, the three tested flower strips were effective in attracting hoverflies, among them natural enemies of insect pests. This study opens new perspectives in the design of intercropping systems with flower strips towards the design of sustainable agro-ecosystems. Improving economic profitability of sowing flower strips could encourage farmers to diversify their agricultural systems and foster conservation biology strategies.

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Bark beetle outbreak enhances biodiversity and foraging habitat of native bees in alpine landscapes of the southern Rocky Mountains

Scientific Reports ◽

10.1038/s41598-020-73273-z ◽

2020 ◽

Vol 10 (1) ◽

Author(s):

Thomas Seth Davis ◽

Paul R. Rhoades ◽

Andrew J. Mann ◽

Terry Griswold

Keyword(s):

Bark Beetle ◽

Forest Structure ◽

Bark Beetles ◽

Large Scale ◽

Tree Mortality ◽

Growing Season ◽

Floral Resources ◽

Foraging Habitat ◽

Pollinator Community ◽

Large Scale Disturbance

Abstract Landscape-scale bark beetle outbreaks alter forest structure with direct and indirect effects on plants and animals in forest ecosystems. Using alpine spruce forest and a native bee community as a study system, we tested how tree mortality from bark beetles impacts bee foraging habitats and populations. Bees were collected across the growing season (early-, middle-, and late-season) for two years using passive trapping methods, and collections were used to analyze patterns in species abundances and diversity. Three important findings emerged: (1) forest stands that were post-outbreak had 62% higher floral density and 68% more floral species during peak bloom, respectively, than non-affected stands; (2) bee captures were highest early-season (June) and were not strongly affected by bark beetle outbreak; however, mean number of bee species and Shannon–Weiner diversity were significantly higher in post-outbreak stands and this effect was pronounced early in the growing season. Corresponding analysis of β-diversity indicated higher accumulation of bee biodiversity in post-outbreak stands and a turnover in the ratio of Bombus: Osmia; (3) bee captures were linked to variation in foraging habitat, but number of bee species and diversity were more strongly predicted by forest structure. Our results provide evidence of increased alpine bee biodiversity in post-outbreak stands and increased availability of floral resources. We conclude that large-scale disturbance from bark beetle outbreaks may drive shifts in pollinator community composition through cascading effects on floral resources, mediated via mortality of overstory trees.

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