Three complete plant-pollinator networks along a secondary successional gradient in critically endangered Renosterveld, South Africa

Abstract

Despite the global recognition of the importance of pollination as an ecosystem function, there remains a dearth of community level studies on the African continent. Here we present three complete pollination networks, along a secondary successional gradient, in critically endangered Renosterveld vegetation within an agri-environment, South Africa. Site selection was based on historical land-use and contemporary vegetation data resulting in a pristine site, a late successional site where agriculture was halted >15 years ago, and an early successional site where agriculture was halted <five years ago. In total, 240 hours of pollinator-plant observations were recorded over a single flowering season. The pristine site was highly specialised in comparison to global datasets – most likely as a result of relative climatic stability through the Quaternary which allowed specialisation to manifest and persist. Both non-pristine sites showed noticeable differences in characteristics when expressed through network indices; however, the early successional site was closer in nature to the pristine site as a result of vegetation structure. Notwithstanding a lack of replication across the successional gradient precluding robust statistical analyses, this study provides important data which allows for the comparison of pollination dynamics in an understudied and vulnerable vegetation type, to plant-pollinator networks at the global and regional scale. In addition, apparent changes to network indices as a result of habitat alteration, suggest that successional trajectory plays an important role in pollination dynamics.