Seasonal changes in hair roots and mycorrhizal colonization in Woollsia pungens (Cav.) F. Muell. (Epacridaceae)

The proportion of the root system comprising hair roots and their ericoid mycorrhizal colonization have been estimated in Woollsia pungens (Cav.) F. Muell. (Epacridaceae) at a site in New South Wales, Australia over a 12 month period. The technique used was a modification of the grid-line intercept method. Hair roots persisted and comprised at least about 50% of the root system all year round. The percentage of root length that was hair root varied with the season, being lowest in April/May (50%) and highest in October (70%). Hair root colonization differed significantly over the 12 month period, being highest over the winter to spring period (June–Oct) but there were infected hair roots present at all times of the year. There was a significant negative relationship between the percentage hair root length infected and log10 transformations of both mean daily maximum and minimum temperatures, but no correlation with rainfall or soil moisture content. These findings contrast with those for south-west Australia where hair roots (and mycorrhizal colonization) are reported to disappear in summer.