DOI: 10.5061/dryad.1zcrjdg0b
title: Landscape simplification leads to loss of plant-pollinator interaction diversity and flower visitation frequency despite buffering by abundant generalist pollinators

description: Global change, especially landscape simplification, is a main driver of
 species loss that can alter ecological interaction networks, with
 potentially severe consequences to ecosystem functions. Therefore,
 understanding how landscape simplification affects the rate of loss of
 plant-pollinator interaction diversity (i.e., number of unique
 interactions) compared to species diversity alone, and the role of
 persisting abundant pollinators, is key to assess the consequences of
 landscape simplification on network stability and pollination services. We
 analysed 24 landscape-scale plant-pollinator networks from standardised
 transect walks along landscape simplification gradients in three
 countries. We compared the rates of species and interaction diversity loss
 along the landscape simplification gradient and then stepwise excluded the
 top 1-20% most abundant pollinators from the data set to evaluate their
 effect on interaction diversity, network robustness to secondary loss of
 species, and flower visitation frequencies in simplified
 landscapes. Interaction diversity was not more vulnerable than
 species diversity to landscape simplification, with pollinator and
 interaction diversity showing similar rates of erosion with landscape
 simplification. We found that 20% of both species and interactions are
 lost with an increase of arable crop cover from 30 to 80% in a landscape.
 The decrease in interaction diversity was partially buffered by persistent
 abundant generalist pollinators in simplified landscapes, which were
 nested subsets of pollinator communities in complex landscapes, while
 plants showed a high turnover in interactions across landscapes. The top
 5% most abundant pollinator species also contributed to network robustness
 against secondary species loss, but could not prevent flowers from a loss
 of visits in simplified landscapes. Although persistent abundant
 pollinators buffered the decrease in interaction diversity in simplified
 landscapes and stabilised network robustness, flower visitation frequency
 was reduced, emphasising potentially severe consequences of further
 ongoing land-use change for pollination services.
description: Plant-pollinator interactions (bees: Hymenoptera: Anthophila; and
 hoverflies: Diptera: Syrphidae) were sampled along transects (1 km x 2 m)
 in different flowering habitat types (e.g., meadows, forest edges,
 hedgerows, flowering crops) in each surveyed agricultural landscape (24
 landscapes in total, n=8 landscapes in Switzerland, Germany, and France).
 The transects were located within 500 m of the center of the landscapes,
 and 3 min were invested for sampling 25 m of the transect (stopping the
 clock when handling the pollinator or flower). Flowering plants were
 surveyed in quadrats of 1 m^2 along the same transects. Three sampling
 rounds were conducted in 2020 (the first in April, the second in May/June,
 and the third in July). Please see the methods section in the published
 manuscript for details about the sampling procedure.
description: # Landscape simplification leads to loss of plant-pollinator interaction
 diversity and flower visitation frequency despite buffering by abundant
 generalist pollinators
 [https://doi.org/10.5061/dryad.1zcrjdg0b](https://doi.org/10.5061/dryad.1zcrjdg0b) ## Description of the data and file structure The Data.zip folder contains three CSV files: ### LandscapeData.csv Data on landscape-scale arable crop cover per landscape was calculated using the R package *landscapemetrics* (Hesselbarth, 2019). * \[Site] = ID of the study landscape * \[arable_PLAND_1000] = Arable crop cover (%) was measured in a 1000 m radius around the center of the study landscapes * \[arable_PLAND_500] = Arable crop cover (%) was measured in a 500 m radius around the center of the study landscapes * \[Country] = Country where the landscapes were located (CH = Switzerland; FR = France; GE = Germany) ### InteractionData.csv Plant-pollinator interactions from transect data of the 24 landscapes (n=8 per country) and 3 sampling rounds. * \[Country] = Country where the landscapes were located (CH = Switzerland; FR = France; GE = Germany) * \[Sampling.Round] = 3 sampling rounds * \[Site] = ID of the study landscape * \[Landuse.Type] = major land-use types, very broad categorization * "Intensive.agriculture" and "Rural.habitat.mosaic" are factor levels * Intensive.agriculture = landscapes largely dominated by monocultures, few semi-natural habitat elements * Rural.habitat.mosaic = landscape also dominated by agriculture, but more small scale and with interspersed semi-natural habitat elements * \[Best.visited.flower.species] = species of the visited flower * \[Best.insect.ID] = species of the flower-visiting bee or hoverfly * \[insect.abundance] = the number of times the specific interaction was observed ### FlowerData.csv Flower survey data from the 24 landscapes (n=8 per country) and 3 sampling rounds. * \[Site] = ID of the study landscape * \[Sampling.Round] = 3 sampling rounds * \[Flower.species] = calculated as flower area, in cm^2, was approximated as circle area with flower diameter/2 = radius, Ammann et al. 2024. * \[Flower.abundance.cm2] = Flower abundance of each flowering plant species * \[Landuse.Type] = major land-use types, very broad categorization * "Intensive.agriculture" and "Rural.habitat.mosaic" are factor levels * Intensive.agriculture = landscapes largely dominated by monocultures, few semi-natural habitat elements * Rural.habitat.mosaic = landscape also dominated by agriculture, but more small scale and with interspersed semi-natural habitat elements * \[Country] = Country where the landscapes were located (CH = Switzerland; FR = France; GE = Germany)