Large-scale differentiation and dynamics in tundra plant populations and vegetation

The inclusion of the botanical projects in the Swedish-Russian Tundra Ecolo gy -94 expedition provided new information on the ecology of tundra plants. The vegetation patterns on different scales were documented, and interpret ed as the result of a complex interaction with environmental factors. The d istribution of fruticose lichens was studied, and it was shown that these l ichens rely on different modes of asexual reproduction for their dispersal. Extreme old genet ages were demonstrated for species of Carer and there we re similar strong indications for lichens. Populations of Carer were geneti cally diverse in spite of old ages and often low levels of flowering. Large differences between sites in flowering and vegetative ramet production (ve getative reproduction) in Carer reflected a asynchronous between-year popul ation fluctuation, which was related to cyclic lemming populations and clim ate; Important gaps in our knowledge of the ecology of tundra plants are po inted out, some of which will hopefully be resolved during the tundra exped ition, Tundra Northwest 1999.