EFFECTS OF ARTIFICIAL ACID MIST ON GROWTH AND REPRODUCTION OF TWO ALPINE PLANT SPECIES IN THE FIELD

Plants of Acomastylis rossii and Bistorta vivipara were treated in the field with artificial acid mists prepared with sulfuric acid, nitric acid, or mixtures of equal parts of these at pH 2.5, 3.5, or 4.5. Highly significant reductions in flower production in A. rossii were noted with sulfuric acid treatments at pH 2.5 and in bulblet production in B. vivipara with nitric acid at pH 2.5 and 3.5, with sulfuric acid at pH 3.5, and with nitric-sulfuric acid mixtures at all pH's. These results apparently relate to the growth forms of the plants, which cause pooling of the acid solutions at their bases. Significant increases in flowering and in leaf number were noted for B. vivipara treated with sulfuric acid, possibly as a promotive effect of sulfate. No effects on vegetative growth were noted in A. rossii. The germinability of seeds (A. rossii) and bulblets (B. vivipara) also was not affected. Differential sensitivity of plant species to artificial acid mist implies that acid precipitation could cause a change in species composition of Colorado alpine plant communities.