RIVER AND LAKE-SEDIMENTS AS SOURCES OF INFECTIVE FRANKIA (ALNUS)

Several Alnus species are commonly found growing along rivers and lake s. Alnus forms root nodules with N-2-fixing Frankia. We used plant bio assays to detect presence of infective Frankia in river and lake sedim ents from northern Sweden and Alaska. Silty river water and superficia l river and lake sediments from all sites contained infective and effe ctive Frankia, but 100-3000 year old lake sediments did not produce no dulated plants. Action by streams, waves and changing water levels tra nsport Frankia in superficial sediments and can provide an inoculum fo r Alnus roots.