PHENOLOGICAL AND GROWTH-RESPONSES OF PAPAVER-RADICATUM ALONG ALTITUDINAL GRADIENTS IN THE CANADIAN HIGH ARCTIC

Phenology and growth of Papaver radicatum Rottb. was monitored over fo ur summers (1990-1993) at 12 sites, along a dolomitic and a granitic a ltitudinal gradient (330 m a.s.l.-770 m a.s.l.) at Sverdrup Pass, cent ral Ellesmere Island, Canada. The gradients provided substantial diffe rences in environmental characteristics. Three of the four seasons (19 90, 1991 and 1993) had more than 400 thawing degree-days (TDD) in the valley, while the 1992 season had less than 300. The granitic sites ha d consistently higher temperatures than the dolomitic sites, despite t heir northerly aspect. Increasing elevation reduced total degree-day a ccumulation (c. 40 degree-days/100 m) and length of potential growing season. The proportion of the population producing flower buds was sim ilar at all sites in any given year, but there were differences among years. Production of flowers and fruits per site, decreased with altit ude along the dolomitic gradient in 1991 and 1992. There was no differ ence in the number of buds or flowers produced per plant with increasi ng altitude, although larger plants with multiple flowers were found o nly on low elevation granitic sites. Plants from the dolomitic sites w ere smaller and flowered, on average, after the site accumulated 150 d egree-days, while plants on the granitic sites were larger and bloomed after 200 degree-days. Papaver is able to grow and reproduce over a w ide range of environmental conditions and moderate climate warming wou ld likely promote its growth and establishment, unless other factors, especially snow-free periods and water availability, become limiting.