Temperature and delayed snowmelt jointly affect the vegetative and reproductive phenologies of four sub-Arctic plants

摘要

Over the coming decades, the Arctic is expected to experience warming temperatures and variable changes in the timing of snowmelt. Both temperature and the timing of snowmelt are important drivers of phenology and reproduction on the tundra. However, few studies have considered their combined effects, making it difficult to predict the direction and magnitude of Arctic plant responses to changing climates. In this 1-year study, we examine how temperature and delayed snowmelt jointly impact the phenology and reproductive effort/success of four common heath tundra species: Empetrum nigrum L., Rhododendron lapponicum (L.) Wahlenb., Dryas integrifolia Vahl, and Arctostaphylos rubra Fernald. We erected snow fences during the winter to increase snowpack on six plots (paired with six control plots), resulting in a consistent 10-day delay in the timing of snowmelt. During the subsequent growing season, we tracked how temperature and the delayed snowmelt on the treatment plots affected the day of onset of species' phenophases, as well as their ability to flower and set fruit. Both temperature and snow addition were significant drivers of phenological onset in these species, though species showed different sensitivities to these factors, possibly as a result of differences in life history strategies. In addition, two of the four species responded positively to snow addition in terms of reproductive effort. Our results emphasize the importance of considering the simultaneous effects of the multiple drivers of Arctic plant phenology.