The tolerances of some epiphytic bryophytes to simulated acid rain and the relation to their respective distribution patterns were studied. Twenty species of bryophytes collected in urban, rural and forested areas were treated by sulfuric and nitric acids and the acid mixture (simulated acid rain) to determine the tolerance of these species. The tolerances were judged by the complete necrosis or chlorosis or new flush of treated shoots. Most of the species could tolerate 1.0 meq/l (pH around 2.6) but died at 10.0 meq/ l. Low concentrations of acid solutions affect the growth of shoots and rhizoids. The tolerance of bark epiphytes seems to be correlated with the nature of the bark. Species preferring conifer trees were more tolerant than those growing on broadleaf trees. No correlation was found between the distribution pattern of species examined in the polluted area and the tolerance to the acidity of simulated rain water.

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