Pollen limitation and reproduction of three plant species across a temperature gradient in western Greenland

Rapid climate change in the Arctic may increase sexual reproduction in plants because of changes in both abiotic factors, such as temperature, and biotic factors, such as pollination. Pollination may currently limit plant reproduction in the Arctic, where cold temperatures hinder pollinator activity. To understand how warming may affect pollination and plant reproduction, we studied three plant species in western Greenland. Two species were hermaphroditic and insect-pollinated (Vaccinium uliginosum and Chamerion latifolium), and one was dioecious and insect- and wind-pollinated (Salix glauca). We measured how pollinator visitation and plant reproduction varied across three temperature zones. We also conducted pollinator exclusion and pollen supplementation experiments to measure pollinator dependence and pollen limitation. Proportion of fruit set in Vaccinium and Salix was pollen limited in every temperature zone, and Vaccinium and Chamerion depended on pollinator-mediated outcrossing for maximum reproductive success. Furthermore, higher pollinator visitation to Vaccinium in the warmer temperature zones mirrored lower pollen limitation and higher fruit set, suggesting that temperature zone indirectly influenced reproduction via changes in pollination. Taken together, our results demonstrate that both abiotic factors and pollination are important in limiting reproduction in the Arctic and that plant–pollinator interactions can mediate the response of plant reproduction to warming.