Response of Saxifraga oppositifolia L. to simulated climate change at three contrasting latitudes

Abstract

Saxifraga oppositifolia, a widespread circum‐arctic and alpine plant species, was exposed to increased temperature at three ITEX sites of different latitudes: Val Bercla in the Swiss Alps (46°N), Latnjajaure in mid‐alpine Northern Sweden (68°N), and Alexandra Fjord, Ellesmere Island (79°N) in the Canadian High Arctic. Phenology, growth, and reproduction were monitored for 2 or 3 consecutive years. Increased temperature had little influence on the phenology of S. oppositifolia, although flowering period was somewhat longer and pollination earlier in the experimental plots. A decrease in the density of flowers on each plant was noted at two sites over 3 years, with a slightly larger decrease in the warmed plots. The few changes observed in reproductive variables (e.g. fruit : flower ratio) are mostly assigned to increased shading by taller growing neighbouring plants of other species, thus limiting performance of the shade‐intolerant S. oppositifolia. It is assumed that survival of this species, especially at the lower limits of its altitudinal and latitudinal distribution, will depend on seed dispersal to new, open habitats.