The Effect of Simulated Acid Rain on Seedling Emergence and Growth of Eleven Woody Species

Abstract

Abstract Seeds of eleven woody species were exposed to 2.3 cm/wk of simulated sulfuric acid rain at pH values of 3.0, 3.5, or 4.0, or to a simulated control rain at approximately pH 5.6. All treatments also contained a neutral mixture of cations and anions based on concentrations reported for Hubbard Brook, N.H. Seeds or seedlings were subject to ambient conditions, except for precipitation. Ambient rainfall was excluded by a partial coveting which allowed some dry deposition. Seeds were planted in winter, 1977; seedlings were harvested the following summer. The dry weights of the top and roots of each seedling were recorded. Although eight species were affected by simulated acid rain, the direction and magnitude of effects varied with species and with treatment. Seedling emergence was stimulated by at least one acid treatment for four species and inhibited for one species. Top growth was stimulated for at least one acid treatment for four species, while root growth was inhibited for one species. Except for one species, whose emergence rate and top growth were both affected, effects were confined to one measured parameter. Forest Sci. 25:393-398.