understanding the role that abiotic environmental factors play in determining the distribution of organisms is of fundamental importance to ecologists. most amphibians are inherently dependent on aquatic habitats and differences in water may influence community structure. however, few comprehensive studies of amphibian distribution in relation to water chemistry exist, but they suggest that the importance of chemistry may differ among regions. the boreal forest contains nearly half of the world's freshwater wetlands, but its amphibian ecology is poorly understood relative to other biomes. i sampled 73 wetlands in northwestern ontario for presence/absence of amphibians using repeated day and night visits between april and august 2003.