Data from: Enhancing plant diversity in agricultural landscapes promotes both rare bees and dominant crop-pollinating bees through complementary increase in key floral resources

1. Enhancing key floral resources is essential to effectively mitigate the
loss of pollinator diversity and associated provisioning of pollination
functions in agro-ecosystems. However, effective floral provisioning
measures may diverge among different pollinator conservation targets, such
as the conservation of rare species or the promotion of economically
important crop pollinators. We examined to what extent such diverging
conservation goals could be reconciled. 2. We analysed plant–bee
visitation networks of 64 herbaceous semi-natural habitats representing a
gradient of plant species richness to identify key resource plants of the
three distinct conservation target groups rare bees (of conservation
concern), dominant wild crop-pollinating bees, and managed
crop-pollinating bees (i.e. honey bees). 3. Considering overall flower
visitation, rare bees tended to visit nested subsets of plant species
which were also visited by crop pollinators (46% and 77% nestedness in the
dissimilarity between rare bees and wild crop pollinators or managed honey
bees, respectively). However, the set of preferred plant species,
henceforth ‘key plant species’ (i.e. those species disproportionately more
visited than expected according to their floral abundance) was
considerably more distinct and less nested among bee target groups. 4.
Flower visits of all bee target groups increased with plant species
richness at a similar rate. Importantly, our analyses revealed that an
exponential increase in the flower abundance of the identified key plant
species and complementarity in the bee visitation pattern across plant
species ─ rather than total flower abundance ─ were the major drivers of
these relationships. 5. Synthesis and applications. We conclude that the
multiple goals of preserving high bee diversity, conserving rare species
and sustaining crop pollinators can be reconciled if key plant species of
different target groups are simultaneously available, which is facilitated
by a high floral resource complementarity in the plant community. The list
of identified key resource plant species we provide here can help
practitioners such as land managers and conservationists to better design
and evaluate pollinator conservation and restoration measures according to
their goals. Our findings highlight the importance of identifying and
promoting such plant species for pollinator conservation in agricultural
landscapes.10-Mar-2017