Extending Plant-Plant Facilitation Theory to Pollinators: Do Desert Shrubs Act as Magnets?

The magnet hypothesis proposes that flowering plants that attract pollinators can increase the relative pollination rates of neighbouring plants. The principal objective of this thesis was to 1) systematically review the theoretical and methodological trends in pollinator facilitation and magnet hypothesis literature, 2) to determine whether desert shrubs act as magnets for pollinators, and 3) extend the study of shrubs as magnets by exploring reciprocitytesting whether the floral island they facilitate in their understory can also act as a double magnet for pollinators. Video and in-situ observation techniques were used to monitor pollinator visitation for both insect and wind-pollinated shrubs and their understories. Shrubs were found to increase bee pollination frequency (but not duration) for understory plants, supporting the magnet hypothesis for shrubs. Evidence for the double magnet hypothesis was not found, as shrub flowers did not show increased pollination rates with the presence of understory annuals.