EFFECTS OF FLOWERING TIME AND TEMPERATURE ON GROWTH AND REPRODUCTION IN LEONTODON AUTUMNALIS VAR TARAXACI A LATE-FLOWERING ALPINE PLANT

In most alpine and arctic plants there is selection for early flowerin g because of the short time available to complete seed production befo re the season terminates. Despite this, some species initiate flowerin g late in the season, but little work has been done on the reproductiv e ecology of such species. This work investigates the reproductive con sequences of late flowering in Leontodon autumnalis var. taraxaci in a lpine southwest Norway during two seasons. In addition, the effects of an experimental increase in growing-season temperature on growth and reproduction are also examined. The reproductive success of Leontodon decreased strongly as the flowering season progressed, possibly as a r esult of increased climatic severity and increased extent of pollen an d resource limitation on reproduction. Experimentally warmed plants pr oduced significantly more and heavier seeds, and flowered more than 1 wk earlier than control plants, showing that temperature conditions in fluence both reproductive processes and flowering phenology. The resul ts suggest that this late-flowering alpine species will bloom earlier, reproduce more, and grow larger under global warming.