RESPONSE TO SIMULATED CLIMATIC-CHANGE IN AN ALPINE AND SUB-ARCTIC POLLEN-RISK STRATEGIST, SILENE ACAULIS

The aim of this study was to test if early no overing species respond with increased seed production to climate warming as is predicted for late-flowering seed-risk strategists. Experimental climate warming of about 3 degrees C was applied to two populations of the cushion-formin g plant Silene acaulis (L.) Jacq. The experiment was run at one subarc tic site and one alpine site for 2 years and 1 year, respectively, usi ng open-top chambers (OTC). The 2-year temperature enhancement at the subarctic site had a marked effect on the flowering phenology. Cushion s inside the OTC started flowering substantially earlier than control cushions. Both the male and female phases developed faster in the OTCs , and maturation of capsules occurred earlier. The cushions also respo nded positively in reproductive terms and produced more mature seeds a nd had a higher seed/ovule ratio. After 1 year temperature enhancement at the alpine site there was a weak trend for earlier flowering, but there was no significant difference in seed production or seed/ovule r atio.