DOI: 10.5061/dryad.wwpzgmsmb
title: Plant cover and plant-pollinator interactions in Central European grasslands (Poland/Czech Republic)

description: Complex socio-economic, political and demographic factors have driven the
 increased conversion of Europe’s semi-natural grasslands to intensive
 pastures. This trend is particularly strong in some of the most biodiverse
 regions of the continent, such as Central and Eastern Europe. Intensive
 grazing is known to decrease species diversity and alter the composition
 of plant and insect communities. Comparatively little is known, however,
 about how intensive grazing influences plant functional traits related to
 pollination and the structure of plant-pollinator interactions. In
 traditional hay meadows and intensive pastures in Central Europe, we
 contrasted the taxonomic and functional group diversity and composition,
 the structure of plant-pollinator interactions and the roles of individual
 species in networks. We found mostly lower taxonomic and functional
 diversity of plants and insects in intensive pastures, as well as strong
 compositional differences among the two grassland management types.
 Intensive pastures were dominated by a single plant with a specialized
 flower structure that is only accessible to a few pollinator groups. As a
 result, intensive pastures have lower diversity and specificity of
 interactions, higher amount of resource overlap, more uniform interaction
 strength and lower network modularity. These findings stand in contrast to
 studies in which plants with more generalized flower traits dominated
 pastures. Our results thus highlight the importance of the functional
 traits of dominant species in mediating the consequences of intensive
 pasture management on plant-pollinator networks. These findings could
 further contribute to strategies aimed at mitigating the impact of
 intensive grazing on plant and pollinator communities.
description: Sampling took place during peak flowering in the middle of June
 2018. We chose this point in time because it represents the period when
 most flowering plants are in bloom, and in the case of the hay meadows it
 reflects the maximum development of the vegetation before mowing (see also
 [38]). Within each of the five sites, we established 10 transects (with
 the exception of one pasture for which we could only place 6 transects),
 each measuring 30x2m. Transects were placed with a minimum distance of 30m
 between them, and towards the nearest field margins. In each transect, we
 visually estimated the percent cover of flowers/inflorescences of each
 plant species (i.e. [40]). We used the standardized transect walks to also
 quantify pollinator species and plant-pollinator interactions. One
 collector walked each transect for an active sampling period of 15 min. We
 thereby sampled over 3 days in total (for 300 min in pastures and 450 min
 in hay meadows), with two days in which a pasture and a hay meadow site
 were sampled in parallel, and a day in which the remaining hay meadow was
 sampled. All Hymenoptera, Diptera and Lepidoptera that
 contacted the reproductive structures of the flowers were treated as
 potential pollinators and collected using sweeping nets (we hereafter
 refer to these groups as pollinators for simplicity); easily identifiable
 species were identified on site and released, while all other individuals
 were collected and frozen for further processing. All plant species were
 identified to species level. Among pollinators, 85.5% of all individuals
 were identified to species level and 99.5% to genus level (see species
 lists in S2 Table, S3 Table).
description: <strong>Sampling location:</strong> Opawskie
 Mountains, at the border between Poland and the Czech Republic (for
 co-ordinates see datatable). <strong>Samling
 period:</strong> middle of June 2018. 
 <strong>Sampling method:</strong> Within each of the
 five sites, we established 10 transects (with the exception of one pasture
 for which we could only place 6 transects), each measuring 30x2m.
 Transects were placed with a minimum distance of 30m between them, and
 towards the nearest field margins. In each transect, we visually estimated
 the percent cover of flowers/inflorescences of each plant species. We used
 the standardized transect walks to also quantify pollinator species and
 plant-pollinator interactions. One collector walked each transect for an
 active sampling period of 15 min. We thereby sampled over 3 days in total
 (for 300 min in pastures and 450 min in hay meadows), with two days in
 which a pasture and a hay meadow site were sampled in parallel, and a day
 in which the remaining hay meadow was sampled. All
 Hymenoptera, Diptera and Lepidoptera that contacted the reproductive
 structures of the flowers were treated as potential pollinators and
 collected using sweeping nets (we hereafter refer to these groups as
 pollinators for simplicity); easily identifiable species were identified
 on site and released, while all other individuals were collected and
 frozen for further processing. All plant species were identified to
 species level. Among pollinators, 85.5% of all individuals were identified
 to species level and 99.5% to genus level."