Ecological Significance of Different Growth Forms of Purple Saxifrage, Saxifraga oppositifolia L., in the High Arctic, Ny-Alesund, Svalbard

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Saxifraga oppositifolia is morphologically variable, and many scientists recognize two morphs; the Prostrate form (P-form) and Cushion form (C-form). In order to investigate the adaptation of the different growth forms, we analyzed the relationships between growth forms, growth patterns, manner of reproduction, tolerance to disturbance and succession. The distribution of the third internode length of shoots showed bimodality, long-internode shoot, and short-internode shoot, and it was closely related with the growth form—P-form and C-form, respectively. When both C-form and P-form plants were growing in the same moist riverbank, they had similar net photosynthesis per dry weight. The colony expansion rate of P-form was faster than C-form and the shoot fragments of P-form were easy to root and establish. On the other hand, C-form had a larger number of flowers per plant dry weight than P-form, and this caused an increase in seed production. These results showed that growth forms and reproductive characteristics were closely related, and P-form was advantageous in vegetative propagation by shoot fragments while C-form was advantageous in sexual reproduction. Morphological variability within population of S. oppositifolia appeared to be adaptive for this species as a pioneer in the primary succession in High Arctic where the selective forces vary spatially and temporally.