DOI: 10.5061/dryad.9ghx3ffpn
title: Grassland extensification enhances nest densities of ground-nesting wild bees

description: Ground-nesting wild bees provide essential pollination services in
 agroecosystems, but they are jeopardized by intensive agricultural
 management. To mitigate such negative impacts, agri-environment schemes
 have been implemented. While the success of enhancing floral food
 resources is relatively well studied, the role of agri-environmental
 schemes in providing suitable nesting habitat remains underexplored. We
 studied the effectiveness of meadow extensification according to the Swiss
 agri-environment scheme in promoting nesting of ground-nesting bees. Using
 a paired design, we quantified their nests during four rounds (March-June)
 in pairs of nine randomly selected extensively (i.e. no fertilizer input,
 postponed first mowing) and nine intensively managed meadows with similar
 soil properties, slope, exposure and landscape context. Nest numbers and
 vegetation characteristics were surveyed in areas of 250 m2. Vegetation
 properties were also assessed in 0.5 m × 0.5 m plots around nest locations
 and randomly selected locations without nests within each meadow to assess
 their role as drivers of nesting incidence (nest presence/absence) at this
 plot scale. We found substantially higher nest numbers of ground-nesting
 bees in extensively (mean ± SE per sampling round = 46.8 ± 14.2) compared
 to intensively managed meadows (0.8 ± 0.3; no nests in three out of nine
 intensively managed meadows). Extensively managed meadows harboured nests
 of several dominant crop pollinator species, including aggregations of
 e.g. Lasioglossum malachurum contributing to high nest densities in some
 of them. Number of nests was negatively related to grass cover and
 vegetation height, which were lower in extensively compared to intensively
 managed meadows. Plot-level nesting incidence increased with bare ground
 and moss cover, and decreased with grass cover. Synthesis and
 applications. Our study shows that extensively managed meadows are better
 nesting habitats for ground-nesting bees than intensively managed meadows,
 if reduced management intensity is associated with altered vegetation
 characteristics such as reduced grass cover and vegetation height, and
 small-scale availability of bare ground, driving these effects. This
 highlights that maintaining and promoting extensive management of meadows
 can promote ground-nesting wild bees, including dominant crop pollinators,
 not only by enhancing floral resources but also by improving nesting
 opportunities in agroecosystems.
description: For a detailed description of the methods used to collect and
 analyse this data please see methods section of the article.
description: # Grassland extensification enhances nest densities of ground-nesting wild
 bees
 [https://doi.org/10.5061/dryad.9ghx3ffpn](https://doi.org/10.5061/dryad.9ghx3ffpn) Data on (1) nest densities of ground-nesting bees in extensively and intensively managed meadows, (2) captured bee species, (3) vegetation characteristics assessed in vegetation plots, (4) soil texture, soil organic carbon content and soil organic matter, as well as (5) soil bulk density are provided in separate data files. All variables and abreviations are explained below. All methods to collect and analyse the data are described in detail in the methods section of the article. ## Description of the data and file structure ### (1) Nest density per sampling round (`nestcount_per_round.csv`): Data containing information on the numbers of ground-nesting bee nests found within the 250 m2 sampling area per sampling round. * `field_id`: Unique field identifier (`[field_id]_[management]`) * `pair`: Meadow pair ID * `management`: Meadow management intensity (`extensive`, `intensive`) * `round`: Sampling round ### (2) Captured bees (`bees.csv`): Data containing information on the captured bee species. * `species`: Species name of the captured specimen * `genus`: Genus name of the captured specimen * `field_id`: Unique field identifier (`[field_id]_[management]`) * `pair`: Meadow pair ID * `management`: Meadow management intensity (`extensive`, `intensive`) ### (3) Vegetation characteristics (`vegetation.csv`): Data containing the results from the vegetation assessments taken at nest and control plots. * `field_id`: Unique field identifier (`[field_id]_[management]`) * `pair`: Meadow pair ID * `management`: Meadow management intensity (`extensive`, `intensive`) * `round`: Sampling round * `type`: Whether the soil sample was taken at the nest (`nest`) or randomly selected control location (`control`) * `nest_pa`: nest presence/absence, same as `type` but coded as `0`/`1` * `cov_bare_ground`: Bare ground cover (%) * `cov_herbs`: Herbaceous vegeation cover (%) * `cov_grass`: Grass cover (%) * `cov_moss`: Moss cover (%) * `cov_litter`: Litter cover (%) * `veg_height`: Vegetation height (cm) ### (4) Soil texture, soil organic carbon content, soil organic matter (`soil_texture.csv`): Data containing the results from mixed soil sample analysis. * `field_id`: Unique field identifier (`[field_id]_[management]`) * `pair`: Meadow pair ID * `management`: Meadow management intensity (`extensive`, `intensive`) * `soc`: Soil organic carbon content (%) * `som`: soil organic matter content (%) * `soil_sand`: sand content (%) * `soil_silt`: silt content (%) * `soil_clay`: clay content (%) ### (5) Soil bulk density (`soil_density.csv`): Data containing the results from the soil dry bulk density analysis from cylindrical soil cores. * `field_id`: Unique field identifier (`[field_id]_[management]`) * `pair`: Meadow pair ID * `management`: Meadow management intensity (`extensive`, `intensive`) * `bulk_density`: soil dry bulk density (g\\cm3)