Data from: Seasonal mass-flowering events dominate landscape effects on plant-pollinator network structure

Agricultural landscapes feature marked seasonal changes in the quality and
quantity of habitats and floral resources supporting pollinating insects.
Seasonal dynamics can affect the structure of plant-pollinator
interactions, yet the relative importance of both landscape elements with
spatio-temporal dynamics and those elements that are more static in space
and time remains largely unknown. Such an understanding is needed to
identify resource-mediated modifications of plant-pollinator network
structures and their functional and management implications. To understand
the spatio-temporal effects of landscape heterogeneity on the structure of
plant-pollinator networks, we sampled plant-pollinator (Apiformes - except
Apis mellifera; Syrphidae) communities over three seasonal periods in
twelve landscapes in central Germany. The landscapes comprised spatial
gradients in the proportion of semi-natural habitat cover and edge
density. To assess temporal changes, we evaluated the cover of
mass-flowering crops in bloom, floral diversity, and honey bee density at
each plant-pollinator sampling event. Spatio-temporally dynamic
characteristics, particularly the cover of mass-flowering crops, were more
important than static characteristics in explaining variation in
plant-pollinator network structure across the three seasonal periods. The
richness of plants and pollinators was generally lower when the proportion
of mass-flowering crops was high. Under such conditions, networks were
more connected, with greater niche overlap among pollinators, and
decreased network specialization (H2’). Richness was higher in landscapes
with high edge density, with an increasing effect on network connectance
up to a certain threshold. The proportion of semi-natural habitat cover
and floral diversity had differential effects on the richness of plants
and pollinators, with strong effects on the dietary niche overlap of the
pollinators, potentially indicating a decrease in competition when
semi-natural habitat cover and flower diversity are high. Synthesis and
application. To better support plant-pollinator communities in
agricultural-dominated landscapes, we suggest incentivizing the planting
of complementary floral resources and preserving or restoring semi-natural
habitat areas. Especially in intensively used agroecosystems, the negative
effects of mass-flowering crops can be mitigated by maintaining
flower-rich edge habitats and relatively small field sizes, which help
support plant and pollinator communities, avoid potential negative effects
of exploitative competition, and ensure the sustainability of pollination
services via increased functional redundancy.