ALNUS-RUBRA (BONG.) MODULE SPORE TYPE DISTRIBUTION IN SOUTHWESTERN BRITISH-COLUMBIA

In red alder (Alnus rubra Bong.) the nitrogen fixing actinomycete Fran kia can be divided into strains which form spores (sp+) within nodules and those that do not. Red alder nodules were collect from 42 sites i n southwestern British Columbia and their spore type was determined. S p+ nodules were found in 18 of the sites, where their proportion range d from 4 to 93%. The distribution of sites with sp+ nodules was clumpe d, with significant autocorrelation at the 0-10 km interval. No sp+ no dules were found in any of the eight stands in the submaritime region, indicating a possible continentality effect on spore type distributio n. There was a significant positive association between the presence o f Rubus spectabilis and the presence sp+ nodules. Stand and soil chemi cal variables were generally poor predictors of the proportion of spnodules, although total soil nitrogen and exchangeable phosphorus acco unted for 36.4 and 28.5% respectively, of the variation in the proport ion of spf nodules on sites where they were present. There was also a small but significant negative relation between soil pH and the propor tion of sp+ nodules and young stands generally did not have any sp+ no dules.