RESPONSE OF SAXIFRAGA-OPPOSITIFOLIA L. TO SIMULATED CLIMATE-CHANGE AT3 CONTRASTING LATITUDES

Saxifraga oppositifolia, a widespread circum-arctic and alpine plant s pecies, was exposed to increased temperature at three ITEX sites of di fferent latitudes: Val Bercla in the Swiss Alps (46 degrees N), Latnja jaure in mid-alpine Northern Sweden (68 degrees N), and Alexandra Fjor d, Ellesmere Island (79 degrees N) in the Canadian High Arctic. Phenol ogy, growth, and reproduction were monitored for 2 or 3 consecutive ye ars. Increased temperature had little influence on the phenology of S. oppositifolia, although flowering period was somewhat longer and poll ination earlier in the experimental plots. A decrease in the density o f flowers on each plant was noted at two sites over 3 years, with a sl ightly larger decrease in the warmed plots. The few changes observed i n reproductive variables (e.g. fruit: newer ratio) are mostly assigned to increased shading by taller growing neighbouring plants of other s pecies, thus limiting performance of the shade-intolerant S. oppositif olia. It is assumed that survival of this species, especially at the l ower limits of its altitudinal and latitudinal distribution, will depe nd on seed dispersal to new, open habitats.