The influence of linear landscape features on pollinator behaviour

This thesis studied the influence of both natural and artificial linear features on pollinator behaviour at medium and landscape scales. Observations along 30m transect, perpendicular to eight different hedgerows revealed that non-foraging pollinators were far more likely to exhibit linear flight next to the hedgerow than they were further out in the field. Using a medium-scale experimental design, three patches of potted Phacelia tanacetifolia (Hydrophyllaceae) were arranged equidistantly with two of the patches being connected by an artificial linear feature. Results demonstrated that there was significantly greater inter-patch movement by bumblebees ( Bombus spp.) between the connected patches than the isolated patch even after the position of the feature was changed. The isolated patch, in contrast, was not approached from the other two patches. Bumblebees demonstrated high patch fidelity but their abundance in the connected patches was not necessarily greater than the isolated patch. There were no significant differences in hoverfly (Syriphidae) abundance between patches. Later, the same experimental array was scaled up to fit within the farm landscape structure, using an existing hedgerow as the connection. A similar pattern of flight directions emerged. In a landscape investigation, the reproductive success of Salvia pratensis (Labiatae) growing in patches with a high number of connecting hedgerows was compared with those plants growing within poorly connected patches. Pollinator abundance, pollen grains per stigma and seed yield, were greater in highly connected patches compared with patches with fewer connecting hedgerows. The overall connectedness of a landscape may therefore be important to both pollinator movement and those plants which depend on them for greater reproductive success. Linear landscape features might represent navigational aids with pollinators orient themselves.