'Bee aware' when weeding! Network analysis of bee-flower visits in the Victorian Alps

Abstract

Bees are known for their important pollination services for crops and wild plants, and are often used as indicators of ecosystem health. The broader public assumes much of this diligent work is primarily carried out by managed and feral populations of the introduced European honeybee (Apis mellifera). However, in Australia, research on the pollination of native plant species by native bee species and the introduced European honeybee are still scant, and there is a lack of studies describing the network structure of bee‐plant interactions. To close this knowledge gap, Johanson, Hoffman, Walker and Nash (2018) examined flower visitation patterns of bees at a landscape scale across ten sites in the Victorian Alps. They characterised this plant–pollinator interaction in a visitation network that allows analysis of (i) how often a bee species visited each plant species, and (ii) the degree of specialisation and nestedness of the network's overall structure. Co‐author associated with the University of Adelaide and La Trobe University, Dr Michael Nash explains that ‘these characteristics give us an indication of how resilient the network is to future ecological disturbance. Native bees and plants in these alpine and subalpine environments are constantly under threat from invasive species, climate change and fire, so ideally we would like a network that is adequately nested/connected and not overly specialised’. In a highly nested network, if a species is lost, the remaining interactions are still connected such that other species are still able to persist in the network. A low specialism network has more generalist rather than specialist pollinators, and is regarded to have more redundancy because the loss of generalists would not negatively affect plant communities as much as the loss of specialists.