DOI: 10.5061/dryad.nk98sf7vd
title: Woodland, cropland and hedgerows promote pollinator abundance in intensive grassland landscapes, with saturating benefits of flower cover

description: To enable reproduction of analyses in the linked journal article,
 we provide a table of habitats, woody linear features and elevation of all
 pollinator survey transect sections. This table can be linked to the
 publicly available data, based on square ID and section ID, to reproduce
 the analyses (except for one discontinued square with ID marked
 ‘NA’ in the publicly available data). Journal article abstract: 1.
 Pollinating insects provide economic value by improving crop yield. They
 are also functionally and culturally important across ecosystems outside
 of cropland. To understand landscape-level drivers of pollinator declines,
 and guide policy and intervention to reverse declines, studies must cover
 (1) multiple insect and plant taxa and (2) a range of agricultural and
 semi-natural land uses. Furthermore, in an era of woodland restoration
 initiatives and rewilding ideologies, the contribution of woodland and
 woody linear features (WLFs; e.g. hedgerows) to pollinator abundance
 demands further investigation. 2. We demonstrate fine-scale analysis of
 high-quality, co-located measurements from a national environmental
 survey. We relate pollinator transect counts to ground-truth habitat and
 WLF maps across 300 1km squares in Wales, UK. We look at effects of
 habitat type, flower cover, WLF density and habitat diversity on summer
 abundance (July and August) of eight insect groups, representing three
 insect orders (Lepidoptera, Hymenoptera and Diptera). 3. Compared with
 improved grassland (the dominant habitat in Wales), pollinator abundance
 is consistently higher in cropland and woodland - especially broadleaved
 woodland. For solitary bees and two hoverfly groups, abundance is
 predicted to be at least 1.5× higher in woodland ecosystems than
 elsewhere. Furthermore, we estimate contributions of WLFs to abundance in
 agriculturally improved habitats to be up to 14% for honeybees and up to
 21% for hoverflies. 4. The abundance of all insect groups increases with
 flower cover, which is a key mechanism through which woodland, cropland
 and grassland support pollinators. Importantly, we observe diminishing
 returns of increasing flower cover for abundance of non-Apis pollinator
 groups, expecting roughly twice the increase in abundance per % flower
 cover from 0-5%, as compared with 10-15%. However, the shape of the
 relationship was inverted for honeybees, which showed steeper increases in
 abundance at higher flower cover. 5. Synthesis & applications: We
 provide a holistic view of the drivers of pollinator abundance in Wales,
 in which flower cover, woodland, WLFs and cropland are critical. We
 propose a key role for woodland creation, hedge-laying and farmland
 heterogeneity within future land management incentive schemes. Finally, we
 suggest targeting of interventions to maximise benefits for non-Apis
 pollinators. Specifically, increasing floral provision in areas where
 existing flower cover is low – e.g. in flower-poor improved grasslands -
 could effectively increase pollinator abundance and diversity, while
 prioritising wild over managed species.
description: Further information on
 habitat and landscape feature survey methodology is available in
 supporting documentation for the published datasets (Maskell et al.,
 2020a, 2020b). This dataset represents an intersection of spatial versions
 of the published datasets with locations of a set of 200m pollinator
 transect sections. The main linked paper (Alison et al. 2021) also
 provides lots of additional information. Habitat, woody linear features
 (WLFs) and elevation variables were extracted for each transect section
 using ArcGIS Desktop 10.6 (ESRI, Redlands, California). To compare
 transect sections in different habitats, we classified the underlying
 broad habitat for 200m pollinator transect sections through intersection
 with habitat polygons. For each section, the broad habitat accounting for
 the greatest proportion of its length was assigned as the dominant habitat
 type. During this process we sought to maximise sample size, while
 avoiding unrepresentative classifications related to missing or ambiguous
 habitat data. As such, we made no dominant habitat assignment if (1) the
 dominant broad habitat accounted for &lt;100m of the section, (2) a
 section had incomplete (&lt;90%) overlap with habitat survey data or
 (3) the dominant broad habitat was recorded as “Mosaic”. We also
 calculated the Shannon index of habitat diversity for each transect
 section, taking into account the total number of broad habitats and the
 dominance among them. To relate flower cover and insect counts to habitat
 classifications at the finest possible scale and resolution, our habitat
 intersections were length-based, and not area- or buffer-based. However, a
 Euclidean buffer was necessary to extract the total density of WLFs (m
 ha<sup>-1</sup>) within 10m of each transect section,
 including managed WLFs (hedges), unmanaged WLFs (lines of trees), and
 forestry linear features (belts of trees or scrub). Outside of GMEP survey
 data, a 5m resolution raster of elevation was provided by Welsh Government
 (the Nextmap Britain DTM by Intermap Technologies). The elevation of each
 transect section was taken as the mean elevation of all vertices in the
 digitised transect section. The final modelled dataset included pollinator
 counts from 4,449 section-visits across 295 1km squares. Maskell, L. C., Astbury, S., Burden, A., Emmett, B. A., Garbutt, A., Goodwin, A., Henrys, P., Jarvis, S., Norton, L. R., Owen, A., Sharps, K., Smart, S. M., Williams, B., Wood, C. M., & Wright, S. M. (2020a). Landscape and habitat area data from the Glastir Monitoring and Evaluation Programme, Wales 2013-2016. <i>NERC Environmental Information Data Centre. (Dataset).</i> https://doi.org/10.5285/82c63533-529e-47b9-8e78-51b27028cc7f Maskell, L. C., Astbury, S., Burden, A., Emmett, B. A., Garbutt, A., Goodwin, A., Henrys, P., Jarvis, S., Norton, L. R., Owen, A., Sharps, K., Smart, S. M., Williams, B., Wood, C. M., & Wright, S. M. (2020b). Landscape linear feature data from the Glastir Monitoring and Evaluation Programme, Wales 2013-2016. <i>NERC Environmental Information Data Centre. (Dataset).</i> https://doi.org/10.5285/f481c6bf-5774-4df8-8776-c4d7bf059d40
description: The headings should be self-explanatory after reading the paper.
 Units for elevation are metres, for WLFs are metres
 ha<sup>-1</sup>.