Pollen limitation and network asymmetry in an endangered oak-savannah ecosystem

Understanding how changes in biodiversity affect plants and plant-pollinator communities is important for their conservation. I measured the effect of conspecific density and co-flowering diversity on pollen limitation in six plant species at six sites over two years to investigate the effect of the co-flowering community on plant reproduction. Plant patches with high conspecific density generally had higher pollen limitation, although the effect was weak and overall pollen limitation was rare. Co-flowering diversity had little effect on pollen limitation. I also collected flower visitors off plants to produce a plant-pollinator interaction network. Networks were highly asymmetric; in general, interacting species did not rely equally on one another for either floral resources or pollination. Larger networks contained more specialized pollinators that were strongly dependent on the plants they visited, producing very negative network asymmetry. Furthermore, introduced plants but not an introduced pollinator, integrated into the networks similarly to native species.