Ecological significance of different growth forms of purple saxifrage, Saxifraga oppositifolia L., in the High Arctic, Ny-Alesund, Svalbard

Saxifraga oppositifolia is morphologically variable, and many scientists re cognize two morphs; the Prostrate form (P-form) and Cushion form (C-form). In order to investigate the adaptation of the different growth forms, we an alyzed the relationships between growth forms, growth patterns, manner of r eproduction, tolerance to disturbance and succession. The distribution of t he third internode length of shoots showed bimodality, long-internode shoot , and short-internode shoot, and it was closely related with the growth for m-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 p er dry weight. The colony expansion rate of P-form was faster than C-form a nd the shoot fragments of P-form were easy to root and establish. On the ot her 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, a nd P-form was advantageous in vegetative propagation by shoot fragments whi le C-form was advantageous in sexual reproduction. Morphological variabilit y within population of S. oppositifolia appeared to be adaptive for this sp ecies as a pioneer in the primary succession in High Arctic where the selec tive forces vary spatially and temporally.