RESPONSE TO EXPERIMENTAL WARMING IN A POPULATION OF PAPAVER RADICATUMIN GREENLAND

In an attempt to simulate the effect of a global climatic change, temp erature manipulations were carried out in a natural population of Papa ver radicatum from a low arctic area on Disko Island, West Greenland. The manipulations were carried out by means of ITEX corners, which are angular plexiglass screens placed around individual plants. The corne rs were placed,vith openings towards four directions and different mic roclimatic conditions were obtained. The corners increase the summer t emperature to different degrees in the four directions. In addition th ey are windscreens and eventually accumulate snow dependent on the win d directions. Dataloggers in a set of corners measured temperatures at the end of one growing season and at the beginning of the next. Sprin g was delayed in all corners due to increased snow cover duration, esp ecially in those facing East and North. Nevertheless, temperatures wer e increased in the corners during the season, and highest temperature sums were obtained in those facing South and West. No temperature incr ease was found in the North-facing corners. No effect was seen on the plants the first year after application of the ITEX centers. In the se cond year an increased biomass was observed in corners facing West and South in accordance with the higher temperatures experienced in these directions. In the third biomass year plants in corners facing West d ecreased and those facing North slightly increased compared to previou s years. After 4 years plants in corners facing West, South and East h ad attained significantly higher biomass than the control plants and t he plants in corners facing North. An earlier onset of flowering was s een in the corners compared to control, and South-facing corners had m ore flowers. An early onset of the growth period is an advantage to fl owering, more so than increased temperatures during the season. Flower ing was prolonged in the corners compared to controls, but there was a higher risk of frost damage to the flowers in the corners.