Adjacent crop type impacts potential pollinator communities and their pollination services in remnants of natural vegetation.

Aim: Pollination plays a crucial role in the conservation of many
plant species persisting in fragmented, human-dominated landscapes.
Pollinators are known to be instrumental in maintaining genetic diversity
and metapopulation dynamics for many plant species and are important for
providing ecological services that are essential in agricultural
landscapes where populations of native plants are highly isolated.
Numerous studies have explored the value of remnant native vegetation for
supporting pollination services to crop species; yet the effect of
mass-flowering crops on the pollinator communities and the pollination
services they provide to native plant communities persisting in fragmented
landscapes are less well-understood. Here, we assess the
influence of the presence and phenology of a mass-flowering crop to
pollinator community structure, abundance and pollen load composition in
remnant vegetation in complex agricultural landscapes. 
Location: South-west Western Australia, Australia.
Methods: We recorded the composition and abundance of insect
flower visitors and their pollen loads in isolated remnants of York
gum-Jam woodlands adjacent to canola (insect-attracting) or wheat
(non-insect-attracting) fields over two years. 
Results: All bees were much more sensitive to adjacent crop type
(neighbouring canola or wheat) than non-bee pollinators. Honeybees were
the most abundant pollinators in canola fields during peak flowering.
Honeybee abundance increased in canola-adjacent reserves post-canola
bloom, potentially indicating a movement into reserves as crop flowering
waned. Native bees were the most diverse in remnant
vegetation.  Pollen loads of native bees were more mixed
(increased pollen richness and evenness) when sampled next to canola
fields compared to wheat fields.  Main conclusion: The
availability of potential insect pollinators to remnant wildflower
communities in agricultural landscapes is context dependent. Whether
sampled communities were adjacent to wheat or canola in a landscape
significantly impacted the abundance of potential pollinators in certain
landscape elements, but not others, and the composition of pollen loads
carried by these insects. Results offer novel insights about the influence
of landscape context on pollinator communities and the potential
pollination services available for the conservation of native plant
species in highly fragmented agricultural landscapes.