EPICUTICULAR WAXES OF 2 ARCTIC SPECIES - COMPOSITIONAL DIFFERENCES INRELATION TO WINTER SNOW COVER

The leaf wax characteristics of Dryas octopetala and Saxifraga opposit ifolia, collected from the high Arctic semi-desert of Svalbard, Norway (79 degrees N, 13 degrees E), were compared and differences in their wax composition related to winter snow cover. The leaf wax composition of the winter-green D. octopetala differed from that of the herbaceou s S. oppositifolia in that high abundances of the triterpenoids, ursol ic acid, oleanoic acid and uvaol, were observed in D. octopetala extra cts but not in S. oppositifolia extracts. D. octopetala leaf waxes wer e consistently lower in n-alkanes and in n-alkanols compared to the le af waxes of S. oppositifolia. Leaf waxes of both species from snow-fre e, wind-swept microsites had significantly higher abundances of n-alka nes than in those plants growing in adjacent, swale areas where snow a ccumulates in winter. It is hypothesized that this higher abundance of n-alkanes may be due to a response to a greater degree of dessication , lower temperatures and lower soil moisture experienced by plants on the snow-free ridge microsites during leaf expansion. In order to test whether these biochemical and anatomical attributes might change in r esponse to short term alterations in winter climate, snow fences were erected on ridge sites. The wax attributes of ridge plants exposed to a single year of increased winter snow cover were examined and the n-a lkane composition of leaf waxes were observed to be more like those of plants growing in adjacent swale areas than for those of ridge plants growing in unmanipulated areas. This shift in leaf wax composition im plies that environmental differences during leaf development can have an influence on final leaf wax composition.