Landscape impacts on pollinator communities in temperate systems: evidence and knowledge gaps

Declines in native bee populations can limit pollination services that support native plant communities and global food production. Mitigating the impacts on pollinators and ecosystems requires conservation actions that promote biodiversity and remain practical for producers. We investigated plantpollinator interaction networks in working grassland landscapes, managed for cattle production and biodiversity, to advance conservation of pollinators in grazed systems. We compared and plotted interactions at the network level. We then used a regression framework to evaluate the influence of floristic availability on pollinator abundance in our system. Overall, we detected seasonal shifts at the network level, with increased specialization between flowers and bees occurring at the end of the sampling season. Furthermore, the response to floristic resources differed between honey bees (Apis mellifera) and native bees. While honey bee abundance increased with exotic floral abundance, native bee abundance showed no relationship with floral abundance and instead was positively associated with floral richness in our system. These findings could be an indication of seasonal shifts in bee activity and interactions with plants or a response to the subset of available resources in grazed systems. These interpretations, along with the detected difference in resource use between honey bees and native bees, suggest foraging preferences differ between these two groups and could influence conservation and management strategies. Furthermore, it demonstrates a need to consider how management practices could influence bee communities differentially across the growing season and suggests conservation actions should promote native floristic resources to benefit native bees.

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“…, Senapathi et al. ). Additionally, pollinator communities need these resources to be temporally distributed (Leong et al.…”

Section: Discussionmentioning

confidence: 99%

Plant–pollinator networks in grassland working landscapes reveal seasonal shifts in network structure and composition

et al. 2019

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“…The stronger decrease suggested for Bombus bumblebees is surprising, given that bumblebee densities and presences are assumed not to be determined by very local landscape characteristic and can benefit from urbanization (Carré et al, ; Kennedy et al, ; Senapathi, Goddard, Kunin, & Baldock, ). However, bumblebees might show an elevated susceptibility to rapid climate change (Kerr et al, ).…”

Section: Discussionmentioning

confidence: 99%

Assessing species richness trends: Declines of bees and bumblebees in the Netherlands since 1945

Dooren

2019

Ecology and Evolution

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Estimating and predicting temporal trends in species richness is of general importance, but notably difficult because detection probabilities of species are imperfect and many datasets were collected in an opportunistic manner. We need to improve our capabilities to assess richness trends using datasets collected in unstandardized procedures with potential collection bias. Two methods are proposed and applied to estimate richness change, which both incorporate models for sampling effects and detection probability: (a) nonlinear species accumulation curves with an error variance model and (b) Pradel capture–recapture models. The methods are used to assess nationwide temporal trends (1945–2018) in the species richness of wild bees in the Netherlands. Previously, a decelerating decline in wild bee species richness was inferred for part of this dataset. Among the species accumulation curves, those with nonconstant changes in species richness are preferred. However, when analyzing data subsets, constant changes became selected for non‐Bombus bees (for samples in collections) and bumblebees (for spatial grid cells sampled in three periods). Smaller richness declines are predicted for non‐Bombus bees than bumblebees. However, when relative losses are calculated from confidence intervals limits, they overlap and touch zero loss. Capture–recapture analysis applied to species encounter histories infers a constant colonization rate per year and constant local species survival for bumblebees and other bees. This approach predicts a 6% reduction in non‐Bombus species richness from 1945 to 2018 and a significant 19% reduction for bumblebees. Statistical modeling to detect species richness time trends should be systematically complemented with model checking and simulations to interpret the results. Data inspection, assessing model selection bias, and comparisons of trends in data subsets were essential model checking strategies in this analysis. Opportunistic data will not satisfy the assumptions of most models and this should be kept in mind throughout.

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“…Pollination efficiency of different crops is strongly related to wild bee species diversity (Földesi et al, ; Winfree et al, ) as well as functional diversity (Fontaine et al, ; Garibaldi et al, ). Research demonstrated that wild bees are threatened by intensive agricultural practices (Kremen, Williams, & Thorp, ) such as high pesticide application (Woodcock et al, ), and/or frequent soil tillage (Williams et al, ), which result in reduction of floral resource availability (Williams et al, ) and contribute to landscape simplification (Senapathi, Goddard, Kunin, & Baldock, ).…”

Section: Introductionmentioning

confidence: 99%

Response of wild bee diversity, abundance, and functional traits to vineyard inter‐row management intensity and landscape diversity across Europe

Kratschmer

Pachinger

Schwantzer

et al. 2019

Ecology and Evolution

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Agricultural intensification is a major driver of wild bee decline. Vineyards may be inhabited by plant and animal species, especially when the inter‐row space is vegetated with spontaneous vegetation or cover crops. Wild bees depend on floral resources and suitable nesting sites which may be found in vineyard inter‐rows or in viticultural landscapes. Inter‐row vegetation is managed by mulching, tillage, and/or herbicide application and results in habitat degradation when applied intensively. Here, we hypothesize that lower vegetation management intensities, higher floral resources, and landscape diversity affect wild bee diversity and abundance dependent on their functional traits. We sampled wild bees semi‐quantitatively in 63 vineyards representing different vegetation management intensities across Europe in 2016. A proxy for floral resource availability was based on visual flower cover estimations. Management intensity was assessed by vegetation cover (%) twice a year per vineyard. The Shannon Landscape Diversity Index was used as a proxy for landscape diversity within a 750 m radius around each vineyard center point. Wild bee communities were clustered by country. At the country level, between 20 and 64 wild bee species were identified. Increased floral resource availability and extensive vegetation management both affected wild bee diversity and abundance in vineyards strongly positively. Increased landscape diversity had a small positive effect on wild bee diversity but compensated for the negative effect of low floral resource availability by increasing eusocial bee abundance. We conclude that wild bee diversity and abundance in vineyards is efficiently promoted by increasing floral resources and reducing vegetation management frequency. High landscape diversity further compensates for low floral resources in vineyards and increases pollinating insect abundance in viticulture landscapes.

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Landscape impacts on pollinator communities in temperate systems: evidence and knowledge gaps

Cited by 173 publications

References 94 publications

Plant–pollinator networks in grassland working landscapes reveal seasonal shifts in network structure and composition

Plant–pollinator networks in grassland working landscapes reveal seasonal shifts in network structure and composition

Assessing species richness trends: Declines of bees and bumblebees in the Netherlands since 1945

Response of wild bee diversity, abundance, and functional traits to vineyard inter‐row management intensity and landscape diversity across Europe

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