EFFECTS OF FLOW REGULATION ON BRYOPHYTES IN NORTH SWEDISH RIVERS

We sampled bryophytes in 52 rapids in regulated and unregulated north Swedish rivers to quantify effects of flow regulation on taxonomic ric hness and abundance of bryophytes. Predictive models based on the cond itions at unregulated sites were used to predict richness and abundanc e at impacted sites and the residuals were used as a measure of the ef fect of regulation. Taxonomic richness was 22% lower than predicted at sites with reduced flow and 26% at sites with regulated but unreduced flow. The overall abundance of bryophytes was not significantly diffe rent from predicted. However, an analysis of the five most abundant sp ecies showed that the abundances of two species, Fontinalis antipyreti ca and F. dalecarlica, was lower than predicted at sites with reduced flow, while the abundance of Blindia acuta and Schistidium agassizii w as higher than predicted at sites with regulated but unreduced flow. C opyright (C) 1996 Elsevier Science Limited